Research Reports

%0 Report %A Qian, Neng %A Wang, Jiayi %A Mueller, Franziska %A Bernard, Florian %A Golyanik, Vladislav %A Theobalt, Christian %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Parametric Hand Texture Model for 3D Hand Reconstruction and Personalization : %G eng %U http://hdl.handle.net/21.11116/0000-0006-9128-9 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2020 %P 37 p. %X 3D hand reconstruction from image data is a widely-studied problem in com-<br>puter vision and graphics, and has a particularly high relevance for virtual<br>and augmented reality. Although several 3D hand reconstruction approaches<br>leverage hand models as a strong prior to resolve ambiguities and achieve a<br>more robust reconstruction, most existing models account only for the hand<br>shape and poses and do not model the texture. To &#64257;ll this gap, in this work<br>we present the &#64257;rst parametric texture model of human hands. Our model<br>spans several dimensions of hand appearance variability (e.g., related to gen-<br>der, ethnicity, or age) and only requires a commodity camera for data acqui-<br>sition. Experimentally, we demonstrate that our appearance model can be<br>used to tackle a range of challenging problems such as 3D hand reconstruc-<br>tion from a single monocular image. Furthermore, our appearance model<br>can be used to de&#64257;ne a neural rendering layer that enables training with a<br>self-supervised photometric loss. We make our model publicly available. %K hand texture model, appearance modeling, hand tracking, 3D hand recon- struction %B Research Report %@ false

%0 Report %A Fox, Gereon %A Meka, Abhimitra %A Zollh&#246;fer, Michael %A Richardt, Christian %A Theobalt, Christian %+ External Organizations Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Live User-guided Intrinsic Video For Static Scenes : %G eng %U http://hdl.handle.net/11858/00-001M-0000-002C-5DA7-3 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2017 %P 12 p. %X We present a novel real-time approach for user-guided intrinsic decomposition of static scenes captured by an RGB-D sensor. In the first step, we acquire a three-dimensional representation of the scene using a dense volumetric reconstruction framework. The obtained reconstruction serves as a proxy to densely fuse reflectance estimates and to store user-provided constraints in three-dimensional space. User constraints, in the form of constant shading and reflectance strokes, can be placed directly on the real-world geometry using an intuitive touch-based interaction metaphor, or using interactive mouse strokes. Fusing the decomposition results and constraints in three-dimensional space allows for robust propagation of this information to novel views by re-projection.We leverage this information to improve on the decomposition quality of existing intrinsic video decomposition techniques by further constraining the ill-posed decomposition problem. In addition to improved decomposition quality, we show a variety of live augmented reality applications such as recoloring of objects, relighting of scenes and editing of material appearance. %B Research Report %@ false

%0 Report %A Sridhar, Srinath %A Markussen, Anders %A Oulasvirta, Antti %A Theobalt, Christian %A Boring, Sebastian %+ Computer Graphics, MPI for Informatics, Max Planck Society External Organizations Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society External Organizations %T WatchSense: On- and Above-Skin Input Sensing through a Wearable Depth Sensor : %G eng %U http://hdl.handle.net/11858/00-001M-0000-002C-402E-D %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2017 %P 17 p. %X This paper contributes a novel sensing approach to support on- and above-skin finger input for interaction on the move. WatchSense uses a depth sensor embedded in a wearable device to expand the input space to neighboring areas of skin and the space above it. Our approach addresses challenging camera-based tracking conditions, such as oblique viewing angles and occlusions. It can accurately detect fingertips, their locations, and whether they are touching the skin or hovering above it. It extends previous work that supported either mid-air or multitouch input by simultaneously supporting both. We demonstrate feasibility with a compact, wearable prototype attached to a user's forearm (simulating an integrated depth sensor). Our prototype---which runs in real-time on consumer mobile devices---enables a 3D input space on the back of the hand. We evaluated the accuracy and robustness of the approach in a user study. We also show how WatchSense increases the expressiveness of input by interweaving mid-air and multitouch for several interactive applications. %B Research Report %@ false

%0 Report %A Sridhar, Srinath %A Mueller, Franziska %A Zollh&#246;fer, Michael %A Casas, Dan %A Oulasvirta, Antti %A Theobalt, Christian %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Real-time Joint Tracking of a Hand Manipulating an Object from RGB-D Input : %G eng %U http://hdl.handle.net/11858/00-001M-0000-002B-5510-A %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2016 %P 31 p. %X Real-time simultaneous tracking of hands manipulating and interacting with external objects has many potential applications in augmented reality, tangible computing, and wearable computing. However, due to dicult occlusions, fast motions, and uniform hand appearance, jointly tracking hand and object pose is more challenging than tracking either of the two separately. Many previous approaches resort to complex multi-camera setups to remedy the occlusion problem and often employ expensive segmentation and optimization steps which makes real-time tracking impossible. In this paper, we propose a real-time solution that uses a single commodity RGB-D camera. The core of our approach is a 3D articulated Gaussian mixture alignment strategy tailored to hand-object tracking that allows fast pose optimization. The alignment energy uses novel regularizers to address occlusions and hand-object contacts. For added robustness, we guide the optimization with discriminative part classication of the hand and segmentation of the object. We conducted extensive experiments on several existing datasets and introduce a new annotated hand-object dataset. Quantitative and qualitative results show the key advantages of our method: speed, accuracy, and robustness. %B Research Report %@ false

%0 Report %A Sridhar, Srinath %A Bailly, Gilles %A Heydrich, Elias %A Oulasvirta, Antti %A Theobalt, Christian %+ Computer Graphics, MPI for Informatics, Max Planck Society External Organizations External Organizations External Organizations Computer Graphics, MPI for Informatics, Max Planck Society %T FullHand: Markerless Skeleton-based Tracking for Free-Hand Interaction : %G eng %U http://hdl.handle.net/11858/00-001M-0000-002B-7456-7 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2016 %P 11 p. %X This paper advances a novel markerless hand tracking method for interactive applications. FullHand uses input from RGB and depth cameras in a desktop setting. It combines, in a voting scheme, a discriminative, part-based pose retrieval with a generative pose estimation method based on local optimization. We develop this approach to enable: (1) capturing hand articulations with high number of degrees of freedom, including the motion of all fingers, (2) sufficient precision, shown in a dataset of user-generated gestures, and (3) a high framerate of 50 fps for one hand. We discuss the design of free-hand interactions with the tracker and present several demonstrations ranging from simple (few DOFs) to complex (finger individuation plus global hand motion), including mouse operation, a first-person shooter and virtual globe navigation. A user study on the latter shows that free-hand interactions implemented for the tracker can equal mouse-based interactions in user performance. %B Research Report %@ false

%0 Report %A Sridhar, Srinath %A Oulasvirta, Antti %A Theobalt, Christian %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Fast Tracking of Hand and Finger Articulations Using a Single Depth Camera : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0024-B5B8-8 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2014 %P 14 p. %B Research Report %@ false

%0 Report %A Kim, Kwang In %A Tompkin, James %A Theobalt, Christian %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Local High-order Regularization on Data Manifolds : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0024-B210-7 %Y Max-Planck Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2014 %P 12 p. %B Research Report %@ false

%0 Report %A Kerber, Jens %A Wand, Michael %A Bokeloh, Martin %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society External Organizations Computer Graphics, MPI for Informatics, Max Planck Society %T Symmetry Detection in Large Scale City Scans : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0024-0427-4 %D 2012 %P 32 p. %X In this report we present a novel method for detecting partial symmetries in very large point clouds of 3D city scans. Unlike previous work, which was limited to data sets of a few hundred megabytes maximum, our method scales to very large scenes. We map the detection problem to a nearestneighbor search in a low-dimensional feature space, followed by a cascade of tests for geometric clustering of potential matches. Our algorithm robustly handles noisy real-world scanner data, obtaining a recognition performance comparable to state-of-the-art methods. In practice, it scales linearly with the scene size and achieves a high absolute throughput, processing half a terabyte of raw scanner data over night on a dual socket commodity PC. %B Research Report %@ false

%0 Report %A Kim, Kwang In %A Kwon, Younghee %A Kim, Jin Hyung %A Theobalt, Christian %+ Computer Graphics, MPI for Informatics, Max Planck Society External Organizations External Organizations Computer Graphics, MPI for Informatics, Max Planck Society %T Efficient Learning-based Image Enhancement : Application to Compression Artifact Removal and Super-resolution : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0027-13A3-E %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2011 %X Many computer vision and computational photography applications essentially solve an image enhancement problem. The image has been deteriorated by a specific noise process, such as aberrations from camera optics and compression artifacts, that we would like to remove. We describe a framework for learning-based image enhancement. At the core of our algorithm lies a generic regularization framework that comprises a prior on natural images, as well as an application-specific conditional model based on Gaussian processes. In contrast to prior learning-based approaches, our algorithm can instantly learn task-specific degradation models from sample images which enables users to easily adapt the algorithm to a specific problem and data set of interest. This is facilitated by our efficient approximation scheme of large-scale Gaussian processes. We demonstrate the efficiency and effectiveness of our approach by applying it to example enhancement applications including single-image super-resolution, as well as artifact removal in JPEG- and JPEG 2000-encoded images. %B Research Report %@ false

%0 Report %A Tompkin, James %A Kim, Kwang In %A Kautz, Jan %A Theobalt, Christian %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Videoscapes: Exploring Unstructured Video Collections : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-F76C-8 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2011 %P 32 p. %B Research Report %@ false

%0 Report %A Granados, Miguel %A Tompkin, James %A Kim, Kwang %A Grau, O. %A Kautz, Jan %A Theobalt, Christian %+ Computer Graphics, MPI for Informatics, Max Planck Society External Organizations Computer Graphics, MPI for Informatics, Max Planck Society External Organizations External Organizations Computer Graphics, MPI for Informatics, Max Planck Society %T How Not to Be Seen -- Inpainting Dynamic Objects in Crowded Scenes : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0010-13C5-3 %F EDOC: 618872 %Y MPI f&#252;r Informatik %C Saarbr&#252;cken %D 2011 %P 35 p. %X Removing dynamic objects from videos is an extremely challenging problem that even visual effects professionals often solve with time-consuming manual frame-by-frame editing. We propose a new approach to video completion that can deal with complex scenes containing dynamic background and non-periodical moving objects. We build upon the idea that the spatio-temporal hole left by a removed object can be filled with data available on other regions of the video where the occluded objects were visible. Video completion is performed by solving a large combinatorial problem that searches for an optimal pattern of pixel offsets from occluded to unoccluded regions. Our contribution includes an energy functional that generalizes well over different scenes with stable parameters, and that has the desirable convergence properties for a graph-cut-based optimization. We provide an interface to guide the completion process that both reduces computation time and allows for efficient correction of small errors in the result. We demonstrate that our approach can effectively complete complex, high-resolution occlusions that are greater in difficulty than what existing methods have shown. %B Research Report

%0 Report %A Berner, Alexander %A Burghard, Oliver %A Wand, Michael %A Mitra, Niloy %A Klein, Reinhard %A Seidel, Hans-Peter %+ External Organizations External Organizations Computer Graphics, MPI for Informatics, Max Planck Society External Organizations External Organizations Computer Graphics, MPI for Informatics, Max Planck Society %T A Morphable Part Model for Shape Manipulation : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-6972-0 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2011 %P 33 p. %X We introduce morphable part models for smart shape manipulation using an assembly of deformable parts with appropriate boundary conditions. In an analysis phase, we characterize the continuous allowable variations both for the individual parts and their interconnections using Gaussian shape models with low rank covariance. The discrete aspect of how parts can be assembled is captured using a shape grammar. The parts and their interconnection rules are learned semi-automatically from symmetries within a single object or from semantically corresponding parts across a larger set of example models. The learned discrete and continuous structure is encoded as a graph. In the interaction phase, we obtain an interactive yet intuitive shape deformation framework producing realistic deformations on classes of objects that are difficult to edit using existing structure-aware deformation techniques. Unlike previous techniques, our method uses self-similarities from a single model as training input and allows the user to reassemble the identified parts in new configurations, thus exploiting both the discrete and continuous learned variations while ensuring appropriate boundary conditions across part boundaries. %B Research Report %@ false

%0 Report %A Tevs, Art %A Wand, Michael %A Ihrke, Ivo %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society International Max Planck Research School, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Graphics - Optics - Vision, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T A Bayesian Approach to Manifold Topology Reconstruction : %G eng %U http://hdl.handle.net/11858/00-001M-0000-000F-1722-7 %F EDOC: 537282 %@ 0946-011X %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2010 %P 23 p. %X In this paper, we investigate the problem of statistical reconstruction of piecewise linear manifold topology. Given a noisy, probably undersampled point cloud from a one- or two-manifold, the algorithm reconstructs an approximated most likely mesh in a Bayesian sense from which the sample might have been taken. We incorporate statistical priors on the object geometry to improve the reconstruction quality if additional knowledge about the class of original shapes is available. The priors can be formulated analytically or learned from example geometry with known manifold tessellation. The statistical objective function is approximated by a linear programming / integer programming problem, for which a globally optimal solution is found. We apply the algorithm to a set of 2D and 3D reconstruction examples, demon-strating that a statistics-based manifold reconstruction is feasible, and still yields plausible results in situations where sampling conditions are violated. %B Research Report

%0 Report %A Fuchs, Martin %A Chen, Tongbo %A Wang, Oliver %A Raskar, Ramesh %A Lensch, Hendrik P. A. %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society External Organizations Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T A shaped temporal filter camera : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-666E-E %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2009-4-003 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2009 %P 25 p. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Havran, Vlastimil %A Zajac, Jozef %A Drahokoupil, Jiri %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society External Organizations Computer Graphics, MPI for Informatics, Max Planck Society %T MPI Informatics building model as data for your research : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-6665-F %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2009-4-004 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2009 %P 113 p. %X In this report we describe the MPI Informatics building model that provides the data of the Max-Planck-Institut f\"{u}r Informatik (MPII) building. We present our motivation for this work and its relationship to reproducibility of a scientific research. We describe the dataset acquisition and creation including geometry, luminaires, surface reflectances, reference photographs etc. needed to use this model in testing of algorithms. The created dataset can be used in computer graphics and beyond, in particular in global illumination algorithms with focus on realistic and predictive image synthesis. Outside of computer graphics, it can be used as general source of real world geometry with an existing counterpart and hence also suitable for computer vision. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Stoll, Carsten %+ Computer Graphics, MPI for Informatics, Max Planck Society %T Optical reconstruction of detailed animatable human body models : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-665F-0 %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2009-4-006 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2009 %P 37 p. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Schultz, Thomas %A Weickert, Joachim %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society External Organizations Computer Graphics, MPI for Informatics, Max Planck Society %T A Higher-order Structure Tensor : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0027-13BC-7 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2009 %X Structure tensors are a common tool for orientation estimation in image processing and computer vision. We present a generalization of the traditional second-order model to a higher-order structure tensor (HOST), which is able to model more than one significant orientation, as found in corners, junctions, and multi-channel images. We provide a theoretical analysis and a number of mathematical tools that facilitate practical use of the HOST, visualize it using a novel glyph for higher-order tensors, and demonstrate how it can be applied in an improved integrated edge, corner, and junction %B Research Report

%0 Report %A Hullin, Matthias B. %A Ajdin, Boris %A Hanika, Johannes %A Seidel, Hans-Peter %A Kautz, Jan %A Lensch, Hendrik P. A. %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Acquisition and analysis of bispectral bidirectional reflectance distribution functions : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-6671-4 %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2009-4-001 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2009 %P 25 p. %X In fluorescent materials, energy from a certain band of incident wavelengths is reflected or reradiated at larger wavelengths, i.e. with lower energy per photon. While fluorescent materials are common in everyday life, they have received little attention in computer graphics. Especially, no bidirectional reflectance measurements of fluorescent materials have been available so far. In this paper, we develop the concept of a bispectral BRDF, which extends the well-known concept of the bidirectional reflectance distribution function (BRDF) to account for energy transfer between wavelengths. Using a bidirectional and bispectral measurement setup, we acquire reflectance data of a variety of fluorescent materials, including vehicle paints, paper and fabric. We show bispectral renderings of the measured data and compare them with reduced versions of the bispectral BRDF, including the traditional RGB vector valued BRDF. Principal component analysis of the measured data reveals that for some materials the fluorescent reradiation spectrum changes considerably over the range of directions. We further show that bispectral BRDFs can be efficiently acquired using an acquisition strategy based on principal components. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Berner, Alexander %A Bokeloh, Martin %A Wand, Martin %A Schilling, Andreas %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society External Organizations External Organizations Computer Graphics, MPI for Informatics, Max Planck Society %T Generalized intrinsic symmetry detection : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-666B-3 %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2009-4-005 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2009 %P 33 p. %X In this paper, we address the problem of detecting partial symmetries in 3D objects. In contrast to previous work, our algorithm is able to match deformed symmetric parts: We first develop an algorithm for the case of approximately isometric deformations, based on matching graphs of surface feature lines that are annotated with intrinsic geometric properties. The sensitivity to non-isometry is controlled by tolerance parameters for each such annotation. Using large tolerance values for some of these annotations and a robust matching of the graph topology yields a more general symmetry detection algorithm that can detect similarities in structures that have undergone strong deformations. This approach for the first time allows for detecting partial intrinsic as well as more general, non-isometric symmetries. We evaluate the recognition performance of our technique for a number synthetic and real-world scanner data sets. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Wang, Danyi %A Belyaev, Alexander %A Saleem, Waqar %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Shape Complexity from Image Similarity : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-66B9-6 %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2008-4-002 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2008 %P 28 p. %X We present an approach to automatically compute the complexity of a given 3D shape. Previous approaches have made use of geometric and/or topological properties of the 3D shape to compute complexity. Our approach is based on shape appearance and estimates the complexity of a given 3D shape according to how 2D views of the shape diverge from each other. We use similarity among views of the 3D shape as the basis for our complexity computation. Hence our approach uses claims from psychology that humans mentally represent 3D shapes as organizations of 2D views and, therefore, mimics how humans gauge shape complexity. Experimental results show that our approach produces results that are more in agreement with the human notion of shape complexity than those obtained using previous approaches. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Schultz, Thomas %A Theisel, Holger %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Crease surfaces: from theory to extraction and application to diffusion tensor MRI : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-66B6-C %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2008-4-003 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2008 %P 33 p. %X Crease surfaces are two-dimensional manifolds along which a scalar field assumes a local maximum (ridge) or a local minimum (valley) in a constrained space. Unlike isosurfaces, they are able to capture extremal structures in the data. Creases have a long tradition in image processing and computer vision, and have recently become a popular tool for visualization. When extracting crease surfaces, degeneracies of the Hessian (i.e., lines along which two eigenvalues are equal), have so far been ignored. We show that these loci, however, have two important consequences for the topology of crease surfaces: First, creases are bounded not only by a side constraint on eigenvalue sign, but also by Hessian degeneracies. Second, crease surfaces are not in general orientable. We describe an efficient algorithm for the extraction of crease surfaces which takes these insights into account and demonstrate that it produces more accurate results than previous approaches. Finally, we show that DT-MRI streamsurfaces, which were previously used for the analysis of planar regions in diffusion tensor MRI data, are mathematically ill-defined. As an example application of our method, creases in a measure of planarity are presented as a viable substitute. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Bokeloh, Martin %A Berner, Alexander %A Wand, Michael %A Seidel, Hans-Peter %A Schilling, Andreas %+ External Organizations External Organizations Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society External Organizations %T Slippage Features : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0023-D3FC-F %U urn:nbn:de:bsz:21-opus-33880 %Y Wilhelm-Schickard-Institut / Universit&#228;t T&#252;bingen %C T&#252;bingen %D 2008 %P 17 p. %B WSI %N 2008-03 %@ false %U http://nbn-resolving.de/urn:nbn:de:bsz:21-opus-33880

%0 Report %A Gall, J&#252;rgen %A Brox, Thomas %A Rosenhahn, Bodo %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society External Organizations Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Global stochastic optimization for robust and accurate human motion capture : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-66CE-7 %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2007-4-008 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2007 %P 28 p. %X Tracking of human motion in video is usually tackled either by local optimization or filtering approaches. While local optimization offers accurate estimates but often looses track due to local optima, particle filtering can recover from errors at the expense of a poor accuracy due to overestimation of noise. In this paper, we propose to embed global stochastic optimization in a tracking framework. This new optimization technique exhibits both the robustness of filtering strategies and a remarkable accuracy. We apply the optimization to an energy function that relies on silhouettes and color, as well as some prior information on physical constraints. This framework provides a general solution to markerless human motion capture since neither excessive preprocessing nor strong assumptions except of a 3D model are required. The optimization provides initialization and accurate tracking even in case of low contrast and challenging illumination. Our experimental evaluation demonstrates the large improvements obtained with this technique. It comprises a quantitative error analysis comparing the approach with local optimization, particle filtering, and a heuristic based on particle filtering. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Bargmann, Robert %A Blanz, Volker %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T A nonlinear viseme model for triphone-based speech synthesis : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-66DC-7 %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2007-4-003 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2007 %P 28 p. %X This paper presents a representation of visemes that defines a measure of similarity between different visemes, and a system of viseme categories. The representation is derived from a statistical data analysis of feature points on 3D scans, using Locally Linear Embedding (LLE). The similarity measure determines which available viseme and triphones to use to synthesize 3D face animation for a novel audio file. From a corpus of dynamic recorded 3D mouth articulation data, our system is able to find the best suited sequence of triphones over which to interpolate while reusing the coarticulation information to obtain correct mouth movements over time. Due to the similarity measure, the system can deal with relatively small triphone databases and find the most appropriate candidates. With the selected sequence of database triphones, we can finally morph along the successive triphones to produce the final articulation animation. In an entirely data-driven approach, our automated procedure for defining viseme categories reproduces the groups of related visemes that are defined in the phonetics literature. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Stoll, Carsten %A de Aguiar, Edilson %A Theobalt, Christian %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T A volumetric approach to interactive shape editing : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-66D6-4 %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2007-4-004 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2007 %P 28 p. %X We present a novel approach to real-time shape editing that produces physically plausible deformations using an efficient and easy-to-implement volumetric approach. Our algorithm alternates between a linear tetrahedral Laplacian deformation step and a differential update in which rotational transformations are approximated. By means of this iterative process we can achieve non-linear deformation results while having to solve only linear equation systems. The differential update step relies on estimating the rotational component of the deformation relative to the rest pose. This makes the method very stable as the shape can be reverted to its rest pose even after extreme deformations. Only a few point handles or area handles imposing an orientation are needed to achieve high quality deformations, which makes the approach intuitive to use. We show that our technique is well suited for interactive shape manipulation and also provides an elegant way to animate models with captured motion data. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Jenke, Philipp %A Wand, Michael %A Strasser, Wolfgang %+ External Organizations Computer Graphics, MPI for Informatics, Max Planck Society External Organizations %T Efficient Surface Reconstruction for Piecewise Smooth Objects : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0023-D3F7-A %U urn:nbn:de:bsz:21-opus-32001 %Y Wilhelm-Schickard-Institut / Universit&#228;t T&#252;bingen %C T&#252;bingen %D 2007 %P 17 p. %B WSI %N 2007-05 %@ false %U http://nbn-resolving.de/urn:nbn:de:bsz:21-opus-32001

%0 Report %A Dyken, Christopher %A Ziegler, Gernot %A Theobalt, Christian %A Seidel, Hans-Peter %+ External Organizations Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T HistoPyramids in Iso-Surface Extraction : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-66D3-A %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2007-4-006 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2007 %P 16 p. %X We present an implementation approach to high-speed Marching Cubes, running entirely on the Graphics Processing Unit of Shader Model 3.0 and 4.0 graphics hardware. Our approach is based on the interpretation of Marching Cubes as a stream compaction and expansion process, and is implemented using the HistoPyramid, a hierarchical data structure previously only used in GPU data compaction. We extend the HistoPyramid structure to allow for stream expansion, which provides an efficient method for generating geometry directly on the GPU, even on Shader Model 3.0 hardware. Currently, our algorithm outperforms all other known GPU-based iso-surface extraction algorithms. We describe our implementation and present a performance analysis on several generations of graphics hardware. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Gall, J&#252;rgen %A Rosenhahn, Bodo %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Clustered stochastic optimization for object recognition and pose estimation : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-66E5-2 %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2007-4-001 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2007 %P 23 p. %X We present an approach for estimating the 3D position and in case of articulated objects also the joint configuration from segmented 2D images. The pose estimation without initial information is a challenging optimization problem in a high dimensional space and is essential for texture acquisition and initialization of model-based tracking algorithms. Our method is able to recognize the correct object in the case of multiple objects and estimates its pose with a high accuracy. The key component is a particle-based global optimization method that converges to the global minimum similar to simulated annealing. After detecting potential bounded subsets of the search space, the particles are divided into clusters and migrate to the most attractive cluster as the time increases. The performance of our approach is verified by means of real scenes and a quantative error analysis for image distortions. Our experiments include rigid bodies and full human bodies. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Herzog, Robert %A Havran, Vlastimil %A Kinuwaki, Shinichi %A Myszkowski, Karol %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society International Max Planck Research School, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Global Illumination using Photon Ray Splatting : %G eng %U http://hdl.handle.net/11858/00-001M-0000-000F-1F57-6 %F EDOC: 356502 %F OTHER: Local-ID: C12573CC004A8E26-88919E23BF524D6AC12573C4005B8D41-HerzogReport2007 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken, Germany %D 2007 %P 66 p. %X We present a novel framework for efficiently computing the indirect illumination in diffuse and moderately glossy scenes using density estimation techniques. A vast majority of existing global illumination approaches either quickly computes an approximate solution, which may not be adequate for previews, or performs a much more time-consuming computation to obtain high-quality results for the indirect illumination. Our method improves photon density estimation, which is an approximate solution, and leads to significantly better visual quality in particular for complex geometry, while only slightly increasing the computation time. We perform direct splatting of photon rays, which allows us to use simpler search data structures. Our novel lighting computation is derived from basic radiometric theory and requires only small changes to existing photon splatting approaches. Since our density estimation is carried out in ray space rather than on surfaces, as in the commonly used photon mapping algorithm, the results are more robust against geometrically incurred sources of bias. This holds also in combination with final gathering where photon mapping often overestimates the illumination near concave geometric features. In addition, we show that our splatting technique can be extended to handle moderately glossy surfaces and can be combined with traditional irradiance caching for sparse sampling and filtering in image space. %B Research Report

%0 Report %A Gall, J&#252;rgen %A Potthoff, J&#252;rgen %A Schn&#246;rr, Christoph %A Rosenhahn, Bodo %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Interacting and Annealing Particle Filters: Mathematics and a Recipe for Applications : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0027-13C7-D %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2007 %Z Review method: peer-reviewed %X Interacting and annealing are two powerful strategies that are applied in different areas of stochastic modelling and data analysis. Interacting particle systems approximate a distribution of interest by a finite number of particles where the particles interact between the time steps. In computer vision, they are commonly known as particle filters. Simulated annealing, on the other hand, is a global optimization method derived from statistical mechanics. A recent heuristic approach to fuse these two techniques for motion capturing has become known as annealed particle filter. In order to analyze these techniques, we rigorously derive in this paper two algorithms with annealing properties based on the mathematical theory of interacting particle systems. Convergence results and sufficient parameter restrictions enable us to point out limitations of the annealed particle filter. Moreover, we evaluate the impact of the parameters on the performance in various experiments, including the tracking of articulated bodies from noisy measurements. Our results provide a general guidance on suitable parameter choices for different applications. %B Research Report

%0 Report %A Langer, Torsten %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Construction of smooth maps with mean value coordinates : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-66DF-1 %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2007-4-002 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2007 %P 22 p. %X Bernstein polynomials are a classical tool in Computer Aided Design to create smooth maps with a high degree of local control. They are used for the construction of B\'ezier surfaces, free-form deformations, and many other applications. However, classical Bernstein polynomials are only defined for simplices and parallelepipeds. These can in general not directly capture the shape of arbitrary objects. Instead, a tessellation of the desired domain has to be done first. We construct smooth maps on arbitrary sets of polytopes such that the restriction to each of the polytopes is a Bernstein polynomial in mean value coordinates (or any other generalized barycentric coordinates). In particular, we show how smooth transitions between different domain polytopes can be ensured. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Belyaev, Alexander %A Langer, Torsten %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Mean value coordinates for arbitrary spherical polygons and polyhedra in $\mathbb{R}^{3}$ : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-671C-2 %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2006-4-010 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2006 %P 19 p. %X Since their introduction, mean value coordinates enjoy ever increasing popularity in computer graphics and computational mathematics because they exhibit a variety of good properties. Most importantly, they are defined in the whole plane which allows interpolation and extrapolation without restrictions. Recently, mean value coordinates were generalized to spheres and to $\mathbb{R}^{3}$. We show that these spherical and 3D mean value coordinates are well-defined on the whole sphere and the whole space $\mathbb{R}^{3}$, respectively. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Albrecht, Irene %A Kipp, Michael %A Neff, Michael Paul %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Multimodal Computing and Interaction Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Gesture modeling and animation by imitation : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-6979-2 %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2006-4-008 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2006 %P 62 p. %X Animated characters that move and gesticulate appropriately with spoken text are useful in a wide range of applications. Unfortunately, they are very difficult to generate, even more so when a unique, individual movement style is required. We present a system that is capable of producing full-body gesture animation for given input text in the style of a particular performer. Our process starts with video of a performer whose gesturing style we wish to animate. A tool-assisted annotation process is first performed on the video, from which a statistical model of the person.s particular gesturing style is built. Using this model and tagged input text, our generation algorithm creates a gesture script appropriate for the given text. As opposed to isolated singleton gestures, our gesture script specifies a stream of continuous gestures coordinated with speech. This script is passed to an animation system, which enhances the gesture description with more detail and prepares a refined description of the motion. An animation subengine can then generate either kinematic or physically simulated motion based on this description. The system is capable of creating animation that replicates a particular performance in the video corpus, generating new animation for the spoken text that is consistent with the given performer.s style and creating performances of a given text sample in the style of different performers. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Theobalt, Christian %A Ahmed, Naveed %A Lensch, Hendrik P. A. %A Magnor, Marcus A. %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Graphics - Optics - Vision, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Enhanced dynamic reflectometry for relightable free-viewpoint video : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-67F4-B %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2006-4-006 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2006 %P 37 p. %X Free-Viewpoint Video of Human Actors allows photo- realistic rendering of real-world people under novel viewing conditions. Dynamic Reflectometry extends the concept of free-view point video and allows rendering in addition under novel lighting conditions. In this work, we present an enhanced method for capturing human shape and motion as well as dynamic surface reflectance properties from a sparse set of input video streams. We augment our initial method for model-based relightable free-viewpoint video in several ways. Firstly, a single-skin mesh is introduced for the continuous appearance of the model. Moreover an algorithm to detect and compensate lateral shifting of textiles in order to improve temporal texture registration is presented. Finally, a structured resampling approach is introduced which enables reliable estimation of spatially varying surface reflectance despite a static recording setup. The new algorithm ingredients along with the Relightable 3D Video framework enables us to realistically reproduce the appearance of animated virtual actors under different lighting conditions, as well as to interchange surface attributes among different people, e.g. for virtual dressing. Our contribution can be used to create 3D renditions of real-world people under arbitrary novel lighting conditions on standard graphics hardware. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Efremov, Alexander %A Mantiuk, Rafal %A Myszkowski, Karol %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Design and evaluation of backward compatible high dynamic range video compression : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-6811-0 %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2006-4-001 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2006 %P 50 p. %X In this report we describe the details of the backward compatible high dynamic range (HDR) video compression algorithm. The algorithm is designed to facilitate a smooth transition from standard low dynamic range (LDR) video to high fidelity high dynamic range content. The HDR and the corresponding LDR video frames are decorrelated and then compressed into a single MPEG stream, which can be played on both existing DVD players and HDR-enabled devices. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Belyaev, Alexander %A Yoshizawa, Shin %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Skeleton-driven Laplacian Mesh Deformations : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-67FF-6 %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2006-4-005 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2006 %P 37 p. %X In this report, a new free-form shape deformation approach is proposed. We combine a skeleton-driven mesh deformation technique with discrete differential coordinates in order to create natural-looking global shape deformations. Given a triangle mesh, we first extract a skeletal mesh, a two-sided Voronoi-based approximation of the medial axis. Next the skeletal mesh is modified by free-form deformations. Then a desired global shape deformation is obtained by reconstructing the shape corresponding to the deformed skeletal mesh. The reconstruction is based on using discrete differential coordinates. Our method preserves fine geometric details and original shape thickness because of using discrete differential coordinates and skeleton-driven deformations. We also develop a new mesh evolution technique which allow us to eliminate possible global and local self-intersections of the deformed mesh while preserving fine geometric details. Finally, we present a multiresolution version of our approach in order to simplify and accelerate the deformation process. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A de Aguiar, Edilson %A Zayer, Rhaleb %A Theobalt, Christian %A Magnor, Marcus A. %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Graphics - Optics - Vision, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T A framework for natural animation of digitized models : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-680B-F %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2006-4-003 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2006 %P 27 p. %X We present a novel versatile, fast and simple framework to generate highquality animations of scanned human characters from input motion data. Our method is purely mesh-based and, in contrast to skeleton-based animation, requires only a minimum of manual interaction. The only manual step that is required to create moving virtual people is the placement of a sparse set of correspondences between triangles of an input mesh and triangles of the mesh to be animated. The proposed algorithm implicitly generates realistic body deformations, and can easily transfer motions between human erent shape and proportions. erent types of input data, e.g. other animated meshes and motion capture les, in just the same way. Finally, and most importantly, it creates animations at interactive frame rates. We feature two working prototype systems that demonstrate that our method can generate lifelike character animations from both marker-based and marker-less optical motion capture data. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Bast, Holger %A Majumdar, Debapriyo %A Schenkel, Ralf %A Theobalt, Christian %A Weikum, Gerhard %+ Algorithms and Complexity, MPI for Informatics, Max Planck Society Algorithms and Complexity, MPI for Informatics, Max Planck Society Databases and Information Systems, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Databases and Information Systems, MPI for Informatics, Max Planck Society %T IO-Top-k: index-access optimized top-k query processing : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-6716-E %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2006-5-002 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2006 %P 49 p. %X Top-k query processing is an important building block for ranked retrieval, with applications ranging from text and data integration to distributed aggregation of network logs and sensor data. Top-k queries operate on index lists for a query's elementary conditions and aggregate scores for result candidates. One of the best implementation methods in this setting is the family of threshold algorithms, which aim to terminate the index scans as early as possible based on lower and upper bounds for the final scores of result candidates. This procedure performs sequential disk accesses for sorted index scans, but also has the option of performing random accesses to resolve score uncertainty. This entails scheduling for the two kinds of accesses: 1) the prioritization of different index lists in the sequential accesses, and 2) the decision on when to perform random accesses and for which candidates. The prior literature has studied some of these scheduling issues, but only for each of the two access types in isolation. The current paper takes an integrated view of the scheduling issues and develops novel strategies that outperform prior proposals by a large margin. Our main contributions are new, principled, scheduling methods based on a Knapsack-related optimization for sequential accesses and a cost model for random accesses. The methods can be further boosted by harnessing probabilistic estimators for scores, selectivities, and index list correlations. We also discuss efficient implementation techniques for the underlying data structures. In performance experiments with three different datasets (TREC Terabyte, HTTP server logs, and IMDB), our methods achieved significant performance gains compared to the best previously known methods: a factor of up to 3 in terms of execution costs, and a factor of 5 in terms of absolute run-times of our implementation. Our best techniques are close to a lower bound for the execution cost of the considered class of threshold algorithms. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Schall, Oliver %A Belyaev, Alexander %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Feature-preserving non-local denoising of static and time-varying range data : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-673D-7 %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2006-4-007 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2006 %P 22 p. %X We present a novel algorithm for accurately denoising static and time-varying range data. Our approach is inspired by similarity-based non-local image filtering. We show that our proposed method is easy to implement and outperforms recent state-of-the-art filtering approaches. Furthermore, it preserves fine shape features and produces an accurate smoothing result in the spatial and along the time domain. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Ziegler, Gernot %A Tevs, Art %A Theobalt, Christian %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T GPU point list generation through histogram pyramids : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-680E-9 %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2006-4-002 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2006 %P 13 p. %X Image Pyramids are frequently used in porting non-local algorithms to graphics hardware. A Histogram pyramid (short: HistoPyramid), a special version of image pyramid, sums up the number of active entries in a 2D image hierarchically. We show how a HistoPyramid can be utilized as an implicit indexing data structure, allowing us to convert a sparse matrix into a coordinate list of active cell entries (a point list) on graphics hardware . The algorithm reduces a highly sparse matrix with N elements to a list of its M active entries in O(N) + M (log N) steps, despite the restricted graphics hardware architecture. Applications are numerous, including feature detection, pixel classification and binning, conversion of 3D volumes to particle clouds and sparse matrix compression. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Havran, Vlastimil %A Herzog, Robert %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T On fast construction of spatial hierarchies for ray tracing : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-6807-8 %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2006-4-004 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2006 %P 40 p. %X In this paper we address the problem of fast construction of spatial hierarchies for ray tracing with applications in animated environments including non-rigid animations. We discuss properties of currently used techniques with $O(N \log N)$ construction time for kd-trees and bounding volume hierarchies. Further, we propose a hybrid data structure blending between a spatial kd-tree and bounding volume primitives. We keep our novel hierarchical data structures algorithmically efficient and comparable with kd-trees by the use of a cost model based on surface area heuristics. Although the time complexity $O(N \log N)$ is a lower bound required for construction of any spatial hierarchy that corresponds to sorting based on comparisons, using approximate method based on discretization we propose a new hierarchical data structures with expected $O(N \log\log N)$ time complexity. We also discuss constants behind the construction algorithms of spatial hierarchies that are important in practice. We document the performance of our algorithms by results obtained from the implementation tested on nine different scenes. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Krawczyk, Grzegorz %A G&#246;sele, Michael %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Photometric calibration of high dynamic range cameras : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-6834-2 %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2005-4-005 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2005 %P 21 p. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Fuchs, Christian %A G&#246;sele, Michael %A Chen, Tongbo %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T An emperical model for heterogeneous translucent objects : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-682F-0 %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2005-4-006 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2005 %P 20 p. %X We introduce an empirical model for multiple scattering in heterogeneous translucent objects for which classical approximations such as the dipole approximation to the di usion equation are no longer valid. Motivated by the exponential fall-o of scattered intensity with distance, di use subsurface scattering is represented as a sum of exponentials per surface point plus a modulation texture. Modeling quality can be improved by using an anisotropic model where exponential parameters are determined per surface location and scattering direction. We validate the scattering model for a set of planar object samples which were recorded under controlled conditions and quantify the modeling error. Furthermore, several translucent objects with complex geometry are captured and compared to the real object under similar illumination conditions. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Langer, Torsten %A Belyaev, Alexander %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Analysis and design of discrete normals and curvatures : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-6837-B %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2005-4-003 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2005 %P 42 p. %X Accurate estimations of geometric properties of a surface (a curve) from its discrete approximation are important for many computer graphics and computer vision applications. To assess and improve the quality of such an approximation we assume that the smooth surface (curve) is known in general form. Then we can represent the surface (curve) by a Taylor series expansion and compare its geometric properties with the corresponding discrete approximations. In turn we can either prove convergence of these approximations towards the true properties as the edge lengths tend to zero, or we can get hints how to eliminate the error. In this report we propose and study discrete schemes for estimating the curvature and torsion of a smooth 3D curve approximated by a polyline. Thereby we make some interesting findings about connections between (smooth) classical curves and certain estimation schemes for polylines. Furthermore, we consider several popular schemes for estimating the surface normal of a dense triangle mesh interpolating a smooth surface, and analyze their asymptotic properties. Special attention is paid to the mean curvature vector, that approximates both, normal direction and mean curvature. We evaluate a common discrete approximation and show how asymptotic analysis can be used to improve it. It turns out that the integral formulation of the mean curvature \begin{equation*} H = \frac{1}{2 \pi} \int_0^{2 \pi} \kappa(\phi) d\phi, \end{equation*} can be computed by an exact quadrature formula. The same is true for the integral formulations of Gaussian curvature and the Taubin tensor. The exact quadratures are then used to obtain reliable estimates of the curvature tensor of a smooth surface approximated by a dense triangle mesh. The proposed method is fast and often demonstrates a better performance than conventional curvature tensor estimation approaches. We also show that the curvature tensor approximated by our approach converges towards the true curvature tensor as the edge lengths tend to zero. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Schall, Oliver %A Belyaev, Alexander %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Sparse meshing of uncertain and noisy surface scattered data : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-683C-1 %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2005-4-002 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2005 %P 20 p. %X In this paper, we develop a method for generating a high-quality approximation of a noisy set of points sampled from a smooth surface by a sparse triangle mesh. The main idea of the method consists of defining an appropriate set of approximation centers and use them as the vertices of a mesh approximating given scattered data. To choose the approximation centers, a clustering procedure is used. With every point of the input data we associate a local uncertainty measure which is used to estimate the importance of the point contribution to the reconstructed surface. Then a global uncertainty measure is constructed from local ones. The approximation centers are chosen as the points where the global uncertainty measure attains its local minima. It allows us to achieve a high-quality approximation of uncertain and noisy point data by a sparse mesh. An interesting feature of our approach is that the uncertainty measures take into account the normal directions estimated at the scattered points. In particular it results in accurate reconstruction of high-curvature regions. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Theobalt, Christian %A Ahmed, Naveed %A de Aguiar, Edilson %A Ziegler, Gernot %A Lensch, Hendrik %A Magnor, Marcus %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Programming Logics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Graphics - Optics - Vision, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Joint Motion and Reflectance Capture for Creating Relightable 3D Videos : %G eng %U http://hdl.handle.net/11858/00-001M-0000-000F-2879-B %F EDOC: 520731 %F OTHER: Local-ID: C1256BDE005F57A8-5B757D3AA9584EEBC12570A7003C813D-TheobaltTR2005 %D 2005 %X \begin{abstract} Passive optical motion capture is able to provide authentically animated, photo-realistically and view-dependently textured models of real people. To import real-world characters into virtual environments, however, also surface reflectance properties must be known. We describe a video-based modeling approach that captures human motion as well as reflectance characteristics from a handful of synchronized video recordings. The presented method is able to recover spatially varying reflectance properties of clothes % dynamic objects ? by exploiting the time-varying orientation of each surface point with respect to camera and light direction. The resulting model description enables us to match animated subject appearance to different lighting conditions, as well as to interchange surface attributes among different people, e.g. for virtual dressing. Our contribution allows populating virtual worlds with correctly relit, real-world people.\\ \end{abstract}

%0 Report %A Fuchs, Martin %A Blanz, Volker %A Lensch, Hendrik P. A. %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Reflectance from images: a model-based approach for human faces : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-683F-C %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2005-4-001 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2005 %P 33 p. %X In this paper, we present an image-based framework that acquires the reflectance properties of a human face. A range scan of the face is not required. Based on a morphable face model, the system estimates the 3D shape, and establishes point-to-point correspondence across images taken from different viewpoints, and across different individuals' faces. This provides a common parameterization of all reconstructed surfaces that can be used to compare and transfer BRDF data between different faces. Shape estimation from images compensates deformations of the face during the measurement process, such as facial expressions. In the common parameterization, regions of homogeneous materials on the face surface can be defined a-priori. We apply analytical BRDF models to express the reflectance properties of each region, and we estimate their parameters in a least-squares fit from the image data. For each of the surface points, the diffuse component of the BRDF is locally refined, which provides high detail. We present results for multiple analytical BRDF models, rendered at novelorientations and lighting conditions. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Dmitriev, Kirill %A Havran, Vlastimil %A Seidel, Hans-Peter %+ Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Faster ray tracing with SIMD shaft culling : %G eng %U http://hdl.handle.net/11858/00-001M-0000-000F-28BB-A %F EDOC: 237860 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2004 %P 13 p. %B Max-Planck-Institut f&#252;r Informatik <Saarbr&#252;cken>: Research Report

%0 Report %A Ivrissimtzis, Ioannis %A Jeong, Won-Ki %A Lee, Seungyong %A Lee, Yunjin %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Neural meshes: surface reconstruction with a learning algorithm : %G eng %U http://hdl.handle.net/11858/00-001M-0000-000F-28C9-A %F EDOC: 237862 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2004 %P 16 p. %B Research Report

%0 Report %A Zayer, Rhaleb %A R&#246;ssl, Christian %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T r-Adaptive parameterization of surfaces : %G eng %U http://hdl.handle.net/11858/00-001M-0000-000F-28E9-2 %F EDOC: 237863 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2004 %P 10 p. %B Max-Planck-Institut f&#252;r Informatik <Saarbr&#252;cken>: Research Report

%0 Report %A Haber, J&#246;rg %A Schmitt, Carina %A Koster, Martin %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Modeling hair using a wisp hair model : %G eng %U http://hdl.handle.net/11858/00-001M-0000-000F-28F6-4 %F EDOC: 237864 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2004 %P 38 p. %B Max-Planck-Institut f&#252;r Informatik <Saarbr&#252;cken>: Research Report

%0 Report %A Zakaria, Nordin %+ Computer Graphics, MPI for Informatics, Max Planck Society %T FaceSketch: an interface for sketching and coloring cartoon faces : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-686B-A %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2003-4-009 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2003 %P 30 p. %X We discuss FaceSketch, an interface for 2D facial human-like cartoon sketching. The basic paradigm in FaceSketch is to offer a 2D interaction style and feel while employing 3D techniques to facilitate various tasks involved in drawing and redrawing faces from different views. The system works by accepting freeform strokes denoting head, eyes, nose, and other facial features, constructing an internal 3D model that conforms to the input silhouettes, and redisplaying the result in simple sketchy style from any user-specified viewing direction. In a manner similar to conventional 2D drawing process, the displayed shape may be changed by oversketching silhouettes, and hatches and strokes may be added within its boundary. Implementation-wise, we demonstrate the feasibility of using simple point primitive as a fundamental 3D modeling primitive in a sketch-based system. We discuss relatively simple but robust and efficient point-based algorithms for shape inflation, modification and display in 3D view. We discuss the feasibility of our ideas using a number of example interactions and facial sketches. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Bekaert, Philippe %A Slusallek, Philipp %A Cools, Ronald %A Havran, Vlastimil %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Cluster of Excellence Multimodal Computing and Interaction External Organizations Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T A custom designed density estimation method for light transport : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-6922-2 %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2003-4-004 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2003 %P 28 p. %X We present a new Monte Carlo method for solving the global illumination problem in environments with general geometry descriptions and light emission and scattering properties. Current Monte Carlo global illumination algorithms are based on generic density estimation techniques that do not take into account any knowledge about the nature of the data points --- light and potential particle hit points --- from which a global illumination solution is to be reconstructed. We propose a novel estimator, especially designed for solving linear integral equations such as the rendering equation. The resulting single-pass global illumination algorithm promises to combine the flexibility and robustness of bi-directional path tracing with the efficiency of algorithms such as photon mapping. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A R&#246;ssl, Christian %A Zeilfelder, Frank %A N&#252;rnberger, G&#252;nther %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society External Organizations Computer Graphics, MPI for Informatics, Max Planck Society %T Visualization of volume data with quadratic super splines : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-6AE8-D %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2004-4-006 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2003 %P 15 p. %X We develop a new approach to reconstruct non-discrete models from gridded volume samples. As a model, we use quadratic, trivariate super splines on a uniform tetrahedral partition $\Delta$. The approximating splines are determined in a natural and completely symmetric way by averaging local data samples such that appropriate smoothness conditions are automatically satisfied. On each tetrahedron of $\Delta$ , the spline is a polynomial of total degree two which provides several advantages including the e cient computation, evaluation and visualization of the model. We apply Bernstein-B{\&#180;e}zier techniques wellknown in Computer Aided Geometric Design to compute and evaluate the trivariate spline and its gradient. With this approach the volume data can be visualized e ciently e.g. with isosurface ray-casting. Along an arbitrary ray the splines are univariate, piecewise quadratics and thus the exact intersection for a prescribed isovalue can be easily determined in an analytic and exact way. Our results confirm the e ciency of the method and demonstrate a high visual quality for rendered isosurfaces. %B Research Report

%0 Report %A Zayer, Rhaleb %A R&#246;ssl, Christian %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Convex boundary angle based flattening : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-6AED-3 %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2003-4-003 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2003 %P 16 p. %X Angle Based Flattening is a robust parameterization method that finds a quasi-conformal mapping by solving a non-linear optimization problem. We take advantage of a characterization of convex planar drawings of triconnected graphs to introduce new boundary constraints. This prevents boundary intersections and avoids post-processing of the parameterized mesh. We present a simple transformation to e ectively relax the constrained minimization problem, which improves the convergence of the optimization method. As a natural extension, we discuss the construction of Delaunay flat meshes. This may further enhance the quality of the resulting parameterization. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Theobalt, Christian %A Li, Ming %A Magnor, Marcus A. %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Graphics - Optics - Vision, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T A flexible and versatile studio for synchronized multi-view video recording : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-6AF2-6 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2003 %P 18 p. %X In recent years, the convergence of Computer Vision and Computer Graphics has put forth new research areas that work on scene reconstruction from and analysis of multi-view video footage. In free-viewpoint video, for example, new views of a scene are generated from an arbitrary viewpoint in real-time from a set of real multi-view input video streams. The analysis of real-world scenes from multi-view video to extract motion information or reflection models is another field of research that greatly benefits from high-quality input data. Building a recording setup for multi-view video involves a great effort on the hardware as well as the software side. The amount of image data to be processed is huge, a decent lighting and camera setup is essential for a naturalistic scene appearance and robust background subtraction, and the computing infrastructure has to enable real-time processing of the recorded material. This paper describes the recording setup for multi-view video acquisition that enables the synchronized recording of dynamic scenes from multiple camera positions under controlled conditions. The requirements to the room and their implementation in the separate components of the studio are described in detail. The efficiency and flexibility of the room is demonstrated on the basis of the results that we obtain with a real-time 3D scene reconstruction system, a system for non-intrusive optical motion capture and a model-based free-viewpoint video system for human actors. ~ %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Tarini, Marco %A Lensch, Hendrik P. A. %A G&#246;sele, Michael %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T 3D acquisition of mirroring objects : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-6AF5-F %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2003 %P 37 p. %X Objects with mirroring optical characteristics are left out of the scope of most 3D scanning methods. We present here a new automatic acquisition approach, shape-from-distortion, that focuses on that category of objects, requires only a still camera and a color monitor, and produces range scans (plus a normal and a reflectance map) of the target. Our technique consists of two steps: first, an improved environment matte is captured for the mirroring object, using the interference of patterns with different frequencies in order to obtain sub-pixel accuracy. Then, the matte is converted into a normal and a depth map by exploiting the self coherence of a surface when integrating the normal map along different paths. The results show very high accuracy, capturing even smallest surface details. The acquired depth maps can be further processed using standard techniques to produce a complete 3D mesh of the object. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Hangelbroek, Thomas %A N&#252;rnberger, G&#252;nther %A R&#246;ssl, Christian %A Seidel, Hans-Peter %A Zeilfelder, Frank %+ Computer Graphics, MPI for Informatics, Max Planck Society External Organizations Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T The dimension of $C^1$ splines of arbitrary degree on a tetrahedral partition : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-6887-A %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2003-4-005 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2003 %P 39 p. %X We consider the linear space of piecewise polynomials in three variables which are globally smooth, i.e., trivariate $C^1$ splines. The splines are defined on a uniform tetrahedral partition $\Delta$, which is a natural generalization of the four-directional mesh. By using Bernstein-B{\&#180;e}zier techniques, we establish formulae for the dimension of the $C^1$ splines of arbitrary degree. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A G&#246;sele, Michael %A Kautz, Jan %A Lang, Jochen %A Lensch, Hendrik P. A. %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Tutorial notes ACM SM 02: a framework for the acquisition, processing and interactive display of high quality 3D models : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-6C86-A %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2002-4-001 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2002 %P 50 p. %X This tutorial highlights some recent results on the acquisition and interactive display of high quality 3D models. For further use in photorealistic rendering or interactive display, a high quality representation must capture two different things: the shape of the model represented as a geometric description of its surface and on the other hand the physical properties of the object. The physics of the material which an object is made of determine its appearance, e.g. the object's color, texture, deformation or reflection properties. The tutorial shows how computer vision and computer graphics techniques can be seamlessly integrated into a single framework for the acquisition, processing, and interactive display of high quality 3D models. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Drago, Frederic %A Martens, William %A Myszkowski, Karol %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society External Organizations Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Perceptual evaluation of tone mapping operators with regard to similarity and preference : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-6C83-0 %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2002-4-002 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2002 %P 30 p. %X Seven tone mapping methods currently available to display high dynamic range images were submitted to perceptual evaluation in order to find the attributes most predictive of the success of a robust all-around tone mapping algorithm. The two most salient Stimulus Space dimensions underlying the perception of a set of images produced by six of the tone mappings were revealed using INdividual Differences SCALing (INDSCAL) analysis; and an ideal preference point within the INDSCAL-derived Stimulus Space was determined for a group of 11 observers using PREFerence MAPping (PREFMAP) analysis. Interpretation of the INDSCAL results was aided by pairwise comparisons of images that led to an ordering of the images according to which were more or less natural looking. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Lensch, Hendrik P. A. %A Kautz, Jan %A G&#246;sele, Michael %A Heidrich, Wolfgang %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Image-based reconstruction of spatially varying materials : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-6CAD-3 %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2001-4-001 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2001 %P 20 p. %X The measurement of accurate material properties is an important step towards photorealistic rendering. Many real-world objects are composed of a number of materials that often show subtle changes even within a single material. Thus, for photorealistic rendering both the general surface properties as well as the spatially varying effects of the object are needed. We present an image-based measuring method that robustly detects the different materials of real objects and fits an average bidirectional reflectance distribution function (BRDF) to each of them. In order to model the local changes as well, we project the measured data for each surface point into a basis formed by the recovered BRDFs leading to a truly spatially varying BRDF representation. A high quality model of a real object can be generated with relatively few input data. The generated model allows for rendering under arbitrary viewing and lighting conditions and realistically reproduces the appearance of the original object. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Daubert, Katja %A Heinrich, Wolfgang %A Kautz, Jan %A Dischler, Jean-Michel %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society External Organizations Computer Graphics, MPI for Informatics, Max Planck Society External Organizations Computer Graphics, MPI for Informatics, Max Planck Society %T Efficient light transport using precomputed visibility : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-6CA7-F %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2001-4-003 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2001 %P 32 p. %X Visibility computations are the most time-consuming part of global illumination algorithms. The cost is amplified by the fact that quite often identical or similar information is recomputed multiple times. In particular this is the case when multiple images of the same scene are to be generated under varying lighting conditions and/or viewpoints. But even for a single image with static illumination, the computations could be accelerated by reusing visibility information for many different light paths. In this report we describe a general method of precomputing, storing, and reusing visibility information for light transport in a number of different types of scenes. In particular, we consider general parametric surfaces, triangle meshes without a global parameterization, and participating media. We also reorder the light transport in such a way that the visibility information is accessed in structured memory access patterns. This yields a method that is well suited for SIMD-style parallelization of the light transport, and can efficiently be implemented both in software and using graphics hardware. We finally demonstrate applications of the method to highly efficient precomputation of BRDFs, bidirectional texture functions, light fields, as well as near-interactive volume lighting. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Lensch, Hendrik P. A. %A Kautz, Jan %A G&#246;sele, Michael %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T A framework for the acquisition, processing, transmission, and interactive display of high quality 3D models on the Web : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-6CAA-9 %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2001-4-002 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2001 %P 20 p. %X Digital documents often require highly detailed representations of real world objects. This is especially true for advanced e-commerce applications and other multimedia data bases like online encyclopaedias or virtual museums. Their further success will strongly depend on advances in the field of high quality object representation, distribution and rendering. This tutorial highlights some recent results on the acquisition and interactive display of high quality 3D models and shows how these results can be seamlessly integrated with previous work into a single framework for the acquisition, processing, transmission, and interactive display of high quality 3D models on the Web. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Choi, Sung Woo %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Linear one-sided stability of MAT for weakly injective domain : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-6CA4-6 %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2001-4-004 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2001 %P 18 p. %X Medial axis transform (MAT) is very sensitive to the noise, in the sense that, even if a shape is perturbed only slightly, the Hausdorff distance between the MATs of the original shape and the perturbed one may be large. But it turns out that MAT is stable, if we view this phenomenon with the one-sided Hausdorff distance, rather than with the two-sided Hausdorff distance. In this paper, we show that, if the original domain is weakly injective, which means that the MAT of the domain has no end point which is the center of an inscribed circle osculating the boundary at only one point, the one-sided Hausdorff distance of the original domain's MAT with respect to that of the perturbed one is bounded linearly with the Hausdorff distance of the perturbation. We also show by example that the linearity of this bound cannot be achieved for the domains which are not weakly injective. In particular, these results apply to the domains with the sharp corners, which were excluded in the past. One consequence of these results is that we can clarify theoretically the notion of extracting ``the essential part of the MAT'', which is the heart of the existing pruning methods. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Lensch, Hendrik P. A. %A G&#246;sele, Michael %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T A framework for the acquisition, processing and interactive display of high quality 3D models : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-6CA1-C %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2001-4-005 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2001 %P 39 p. %X This tutorial highlights some recent results on the acquisition and interactive display of high quality 3D models. For further use in photorealistic rendering or object recognition, a high quality representation must capture two different things: the shape of the model represented as a geometric description of its surface and on the other hand the appearance of the material or materials it is made of, e.g. the object's color, texture, or reflection properties. The tutorial shows how computer vision and computer graphics techniques can be seamlessly integrated into a single framework for the acquisition, processing, and interactive display of high quality 3D models. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Kautz, Jan %A Heidrich, Wolfgang %A Daubert, Katja %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Bump map shadows for openGL rendering : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-6D50-9 %U http://domino.mpi-inf.mpg.de/internet/reports.nsf/NumberView/2000-4-001 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2000 %P 18 p. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Choi, Sung Woo %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Hyperbolic Hausdorff distance for medial axis transform : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-6D4A-A %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2000 %P 30 p. %X Although the Hausdorff distance is a popular device to measure the differences between sets, it is not natural for some specific classes of sets, especially for the medial axis transform which is defined as the set of all pairs of the centers and the radii of the maximal balls contained in another set. In spite of its many advantages and possible applications, the medial axis transform has one great weakness, namely its instability under the Hausdorff distance when the boundary of the original set is perturbed. Though many attempts have been made for the resolution of this phenomenon, most of them are heuristic in nature and lack precise error analysis. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Kobbelt, Leif P. %A Bischoff, Stephan %A K&#228;hler, Kolja %A Schneider, Robert %A Botsch, Mario %A R&#246;ssl, Christian %A Vorsatz, Jens %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T Geometric modeling based on polygonal meshes : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-6D4D-4 %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 2000 %P 52 p. %X While traditional computer aided design (CAD) is mainly based on piecewise polynomial surface representations, the recent advances in the efficient handling of polygonal meshes have made available a set of powerful techniques which enable sophisticated modeling operations on freeform shapes. In this tutorial we are going to give a detailed introduction into the various techniques that have been proposed over the last years. Those techniques address important issues such as surface generation from discrete samples (e.g. laser scans) or from control meshes (ab initio design); complexity control by adjusting the level of detail of a given 3D-model to the current application or to the available hardware resources; advanced mesh optimization techniques that are based on the numerical simulation of physical material (e.g. membranes or thin plates) and finally the generation and modification of hierarchical representations which enable sophisticated multiresolution modeling functionality. %B Research Report / Max-Planck-Institut f&#252;r Informatik

%0 Report %A Haber, J&#246;rg %A Seidel, Hans-Peter %+ Computer Graphics, MPI for Informatics, Max Planck Society Computer Graphics, MPI for Informatics, Max Planck Society %T A framework for evaluating the quality of lossy image compression : %G eng %U http://hdl.handle.net/11858/00-001M-0000-0014-6F38-D %Y Max-Planck-Institut f&#252;r Informatik %C Saarbr&#252;cken %D 1999 %P 20 p. %X In this research report we present a framework for evaluating and comparing the quality of various lossy image compression techniques based on a multiresolution decomposition of the image data. In contrast to many other publications, much attention is paid to the interdependencies of the individual steps of such compression techniques. In our result section we are able to show that it is quite worthwile to fine-tune the parameters of every step to obtain an optimal interplay among them, which in turn leads to a higher reconstruction quality. %B Research Report / Max-Planck-Institut f&#252;r Informatik