Support for InstantNGP

[lucasew]

InstantNGP [1] is a toolkit to train Neural Radiance Fields (NERF).

Basically video/set of images in, 3D model out.

I started packaging it here [2] and got it working along with colmap. It needs some tweaking to work with this repo.

I don't know yet if it can be patched to work with HIP. Its not based in Pytorch and the dependencies are vendored so self contained. The derivation already exposes the generated dynamic lib as a Python package and the CUDA target is old enough to work with the Tesla K80 from GCP.

This build is for the headless mode. More work is needed for the GUI to work. I used it headless because I was using it in a headless instance.

[1] https://github.com/NVlabs/instant-ngp
[2] https://github.com/lucasew/nixcfg/blob/a8aa81d09c3f68a9d330e838c71db594b063fc80/nix/pkgs/instantngp.nix#LL1

[pbsds]

leaving this here: https://docs.nerf.studio/en/latest/nerfology/methods/instant_ngp.html