Nov 11 2008

improved background subtraction and debugged voxel carving

Published by Martijn at 15:46 under PhD lab book

  • Improved background subtraction by enabling the upper shadow threshold (m_nBeta). This enables doing the inverse of shadow removal, highlight removal. It improves backsub results greatly by removing large light spots caused by movement of the sun and clouds. Currently set to 3 for detecting spots coloured similar to the background but 3x as bright.
  • Fixed problems with VoxelCarving. It turns out to be important to undistort the images first, before mapping them to the voxel grid. This fixesthe projection. Voxel carving result now looks a lot better.
  • Michael mentionned the difference between voxel carving using only the mapping of the voxel’s centroid to the foreground image to determine wheter it should be classified as foreground or carving using the mapping of all 8 corners of the voxel. The second one turns out to be a lot slower (because of 8 instead of 1 match, but gives more acurate results
  • Next thing to try is changing the size of the voxel grid. When are there too few voxels to make a correct classification?
  • Furthermore, improbe backsub result to create better foreground segmented people.
  • Also: think of ways to get rid of “shadow people”. People sometimes get duplicated because voxelcarving canĀ  not distinguish between two spatial positions.

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