bmild / nerf

Code release for NeRF (Neural Radiance Fields)
http://tancik.com/nerf
MIT License
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Understanding of NDC rays in NeRF #206

Open ShriAjayKumar opened 4 months ago

ShriAjayKumar commented 4 months ago

I have been racking my brain on this for few days. So please help me with these following queries:

  1. What is the need to transform ray origins and ray directions in NDC frame ? I have already read https://github.com/bmild/nerf/issues/18, but still did not follow through.
    In the paper, I read that the purpose for this is to preserve parallel lines and to have linear disparity-z relationship. But, the latter , though helps in better sampling and faster calculations, creates an inaccurate 3d space reconstruction. So, why is this desired ?

  2. Why is NDC rays used in NeRF but not in TinyNeRF ?

  3. What does "forward facing scenes" in the paper mean ? What does this have to do with NDC ?