ShapeFromSilhouette – part2

extracting color was a little bit harder than I thought.

for each voxel , I test the length of the normal. if the length is different than zero I assume being at the surface of the volume (ie where density goes from 0 to 1) and continue.
The dot product between the normal and CameraRay is calculated . if > 0 (or bigger than a given positive threshold) , continue.
the last thing to test is self occlusion.this was done by integrating the volume density from P to Camera using integrate3d.
the more density , the less color will be kept.

this is done for each picture and color is accumulated from frame to frame in an i3d.

in my first attempt the colors were screened together.The result was washed out and blurry.

by keeping only the best Color (ie best dot) per voxel , result is much sharper (but shows discontinuity)





I tried to match (approximately) voxel resolution and picture resolution and ended up with more than 400 Millions voxels in the final i3d.

finally I spent an hour with uvlayout (this is a great software) to get nice and undistorted uv’s and baked the color for Photoshop retouching.



a piece of the final map


there are certainly other techniques to extract/mix colors and hide seams , but this sould be enough to start manual work.

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