Fix conversion from Blender to COLMAP coords in NeRF camera import. #111
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Hi, Thank you so much for actually finding this. Have you run it in any of the blender datasets of nerf-synthetic? What PSNR did you get in the end in the test set? |
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I tested the fix on "lego" and "ship", both seemed to work exactly as before. Since the error metric doesn't penalize the model ending up flipped 180 degrees in world space, I would expect the PSNR to be exactly the same (I didn't check though). The only positive effect is compatibility with a custom initial point cloud. |
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…raphdeco-inria#111) Co-authored-by: Jakub Červený <jakub.cerveny@melowntech.com>
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Update README.md Update README.md Update README.md Update README.md Update README.md Update README.md Update README.md Update README.md Update README.md Fix conversion from Blender to COLMAP coords in NeRF camera import. (graphdeco-inria#111) Co-authored-by: Jakub Červený <jakub.cerveny@melowntech.com>
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The NeRF camera import code incorrectly converts from OpenGL/Blender camera axes to COLMAP camera axes.
The original code flips the sign of YZ rows of the world-to-camera matrix, which turns the world 180 degrees around the X axis, but doesn't convert the camera. Then the line
T = -matrix[:3, 3]moves the camera to an antipodal point, which accidentally works, but the cameras stay in the Blender format and project "backwards". With the random initial point cloud the synthetic NeRF benchmarks work, but using a initial point cloud from custom data fails.The Blender cameras need to be converted while the matrix is still in the camera-to-world format, which is what this PR does.
(The PR addresses issue #100)