Xinerama OpenGL Stereo (Art Tevs)

You can also let run your program in real time by using stereo view techniques. To understand how to do this, you can read some information on realtime stereo viewing here: 3D Stereo Rendering Using OpenGL (and GLUT).

There are some examples how it will looks like in real time (rendered with OpenGL in widescreen mode 16:9)

Here is a list of steps (in my own words) on how to do stereo view (not only for 019):

• open rendering window with double width (for 019 it has to be 2560 pixels)
• precalculate projection matrices for both eyes (left, right) using this parameters: eye separation=0.04 (4 cm), focal length=~1 (1 m). Better you find out what parameters are best for your application. But this should be optimal.
• let OpenGL do this calculation for you:
// Calculate some variables
float halfEyeSeparation = eyeSeparation / 2;
float ratio = float(viewPortWidth)/float(viewPortHeight); //use your vieport settings (for 019 better use 1280x1028)
float radiance = DEGTORAD * fieldOfView / 2; //DEGTORAD = (PI / 180.0f)
float wd2 = nearPlane * tan(radiance); // nearPlane is the near plane of your view frustum
float ndfl = nearPlane / focalLength;

// Calculaions for right eye
float left = -ratio * wd2 - 0.5 * eyeSeparation * ndfl;
float right = ratio * wd2 - 0.5 * eyeSeparation * ndfl;
float top = wd2;
float bottom = -wd2;

// Use OpenGL to calculate projection matrix
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
glFrustum(left,right,bottom,top,nearPlane,farPlane);
glGetFloatv(GL_PROJECTION_MATRIX, asymmetricProjectionRight); // store projection matrix for right eye in float[16] array

// Calculation for left eye
left = -ratio * wd2 + 0.5 * eyeSeparation * ndfl;
right = ratio * wd2 + 0.5 * eyeSeparation * ndfl;
top = wd2;
bottom = -wd2;

// Use OpenGL to do calculations for us
glLoadIdentity();
glFrustum(left,right,bottom,top,nearPlane,farPlane);
glGetFloatv(GL_PROJECTION_MATRIX, asymmetricProjectionLeft); //store projection of left eye

// Return back to modelview matrix mode
glPopMatrix();
glMatrixMode(GL_MODELVIEW);


• in your rendering code, do something like this:
• set viewport to left eye (glViewport(0,0, 1280, height))
• load your precalculated left eye projection matrix
  ( glMatrixMode(GL_PROJECTION);
glLoadMatrixf(asymmetricProjectionLeft);
glMatrixMode(GL_MODELVIEW);)
• camera.pos -= camera.rightDirection * eyeSeparation/2 (move camera position to left eye)
• render your stuff (NOTE: be careful if you use render to texture: you must copy the whole framebuffer, but only the left eye part)
• now switch the viewport to the right eye (glViewport(1280,0,2560,height))
• move your camera again but now to the right (according to what you have done before: restore modelview and move with eyeSeparation/2 or with eyeSeparation, if you moved your camera without pushing the modelview matrix on the stack)
• load the projection matrix for the right eye
• render your stuff

You can also download cCamera-class and let cCamera do this work for you :-)
This class also provides some more useful methods: for example frustum culling. You are free to use it in your applications.

Stereo video encoding (Gernot Ziegler)

After fiddling around with mplayer and X on the computer francium in the presentation room, I should now be possible to generate MPEG2 stereo movies for presentation in 019.

The advantage of it, to having the real application running, is that you can create a voice-over, background music and, especially, that you can pre-create 25 fps animations from non-realtime applications.

An interesting idea would also be to generate two versions of important presentation footage, one in mono for conference submission, the other one in stereo for 019 !

The encoder requires the following as input:

• Data format: PNG, PPM (JPEG is lossy, but works)
• Naming convention: Anything in the style of printf("xyz%06d", number); , e.g.: pic0000.ppm, pic0001.ppm, etc. (the tool png2yuv or jpeg2yuv is used)
• Two frames arranged besides each other, like here:
  
  
  (but I can also show you how to use ImageMagick's convert to merge left and right frame into one)

These are the commands that I currently use:

For encoding I utilize the MJPEGTools, with the special --no-constraints to achieve resolutions above HDTV:
png2yuv -j %08d.png -I p -f 25 -b 1 | mpeg2enc --no-constraints -f 3 -q 3 -b 10000 -o out.m2v

For playback:
mplayer -fs -screenw 2560 -screenh 1024 -vo xv -loop 0 out.m2v

Let me know (well in advance ;) ) if you want to generate some footage.