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(b)
Martin Fuchs, MPI Informatik
Volker Blanz, Siegen
University
Hans-Peter Seidel, MPI Informatik
Hendrik P. A. Lensch, MPI Informatik
Abstract
Captured reflectance fields tend to provide a relatively coarse sampling of the incident light directions. As a result, sharp illumination features, such as highlights or shadow boundaries, are poorly reconstructed during relighting; highlights are disconnected, and shadows show banding artefacts. In this paper, we propose a novel interpolation technique for 4D reflectance fields that reconstructs plausible images even for non-observed light directions. Given a sparsely sampled reflectance field, we can effectively synthesize images as they would have been obtained from denser sampling. The processing pipeline consists of three steps: (1) segmentation of regions where intermediate lighting cannot be obtained by blending, (2) appropriate flow algorithms for highlights and shadows, plus (3) a final reconstruction technique that uses image-based priors to faithfully correct errors that might be introduced by the segmentation or flow step. The algorithm reliably reproduces scenes that contain specular highlights, interreflections, shadows or caustics.
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(a) Our acquisition setup allows for capturing reflectance samples for arbitrary incident light directions and varying light source extent. We can perform pre-filtering and adaptive sampling. (b) By performing non-linear interpolation of high lights, caustics and shadows we can hierarchically synthesize images for for arbitrary light source directions (red dots) even from a sparse input (black triangulation). |
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(a) Linear interpolation of reflectance samples lead to an artificial segmentation of the highlight region. (b) Our non-linear interpolation generates a smooth highlight from the same input data with about 230 directions. The result comes close to the ground truth captured for about 10000 direction. |
Movies:
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(a) linear interpolation |
(b) non-linear interpolation |
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(c) linear interpolation |
(d) non-linear interpolation |
Publications:
Martin Fuchs, Volker Blanz, Hendrik P. A. Lensch, and Hans-Peter Seidel.
Martin Fuchs, Hendrik P. A. Lensch, Volker Blanz, and Hans-Peter Seidel.
Superresolution Reflectance Fields: Synthesizing images for intermediate light
directions. In Proceedings EUROGRAPHICS 2007, pages 447-456.