HybridNeRF: Efficient Neural Rendering

-No Collision/poor collision on NERFs and GS: to have a proper interactive world, you usually need accurate character collision so that your character or vehicle can move along the floor/ground (as opposed to falling thru it) run into walls, go through door frames, etc. NERFs suffer from the same issues as photogrammetry in that they need “structure from motion” (COLMAP or similar) to give them a mesh or 3-D output that can be meshed for collision to register off of. The mesh from reality capture is noisy, and is not simple geometry. Think millions of triangles from a laser scanner or camera for “flat” ground that a video game would use 100 triangles for.

-Scanning: there’s no scanner available that provides both good 3-D information and good photo realistic textures at a price people will want to pay. Scanning every square inch of playable space in even a modest sized house is a pain, and people will look behind the television, underneath the furniture and everywhere else that most of these scanning videos and demos never go. There are a lot of ugly angles that these videos omit where a player would go.

-Post Processing: of you scan your house or any other real space, you will have poor lighting unless you took the time to do your own custom lighting and color setup. That will all need to be corrected in post process so that you can dynamically light your environment. Lighting is one of the most next generation things that people associate with games and you will be fighting prebaked shadows throughout the entire house or area that you have scanned. You don’t get away from this with NERFs or gaussian splats, because those scenes also have prebaked lighting in them that is static.

Object Destruction and Physics: I Love the game teardown, and if you want to see what it’s like to actually bust up and destroy structures that have been physically scanned, there is a plug-in to import reality capture models directly into the game with a little bit of modding. That said, teardown is voxel based, and is one of the most advanced engines that has been built to do such a thing. I have seen nothing else capable of doing cool looking destruction of any object, scanned or 3D modeled, without a large studio effort and a ton of optimization.

Lighting is the big issue, IMO. As soon as you want any kind of interactivity besides moving the camera you need dynamic lighting. The problem is you're going to have to mix the captured absolutely perfect real-world lighting with extremely approximate real-time computed lighting (which will be much worse than offline-rendered path tracing, which still wouldn't match real-world quality). It's going to look awful. At least, until someone figures out a revolutionary neural relighting system. We are pretty far from that today.

Scale is another issue. Two issues, really, rendering and storage. There's already a lot of research into scaling up rendering to large and detailed scenes, but I wouldn't say it's solved yet. And once you have rendering, storage will be the next issue. These scans will be massive and we'll need some very effective compression to be able to distribute large scenes to users.