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Current RTX hardware is rather lame to only get to 1spp isn’t it? It’s not even clear that it’s the right approach. A graphics engineer I know has this to say

Current RTX hardware is rather lame to only get to 1spp isn’t it? It’s not even clear that it’s the right approach. A graphics engineer I know has this to say about it. “Telling me you made hardware accelerated BVH is like telling me you implemented hardware accelerated bubble sort.”

yazzku 4y ago
I don't think real-time ray tracing is lame. Diffuse is low-frequency and redundant, denoisers work magically well. It's 1spp per frame, but the denoiser is essentially allowing the application to distribute the workload across frames. For perfect specular a single ray is sufficient, and glossy is somewhere in between the two. The limitation doesn't have to do much with firing more rays than handling more complex materials; what I just described decouples diffuse/specular and is how games are doing it these days. But if the current materials are plausible, then what's wrong with this approach? I do think it is the/a right approach... when used judiciously and when an alternative rasterization approach doesn't already exist or has obvious flaws. For example, some games use a hybrid SSR-RT reflection; do the SSR first, then fire rays where the SSR misses (insufficient information in screen-space.) I think the UE5 Matrix demo does this. You kind of get the best of both approaches. The article in this sense proposes a false dichotomy; to choose between the complex "hacks" of rasterization, or the easiness of RT. Except that rasterization has decades of research and solutions are well-known and already implemented, and RT is not 'do the dumb thing and let the hardware do the work'. I don't think BVH construction is as bad as your friend paints it. There are semi-parallel approaches available, i.e. https://www.researchgate.net/publication/327216026_PLOCTree_A_Fast_High-Quality_Hardware_BVH_Builder https://www.researchgate.net/publication/327216026_PLOCTree_...

yazzku 4y ago

I don't think real-time ray tracing is lame. Diffuse is low-frequency and redundant, denoisers work magically well. It's 1spp per frame, but the denoiser is essentially allowing the application to distribute the workload across frames. For perfect specular a single ray is sufficient, and glossy is somewhere in between the two. The limitation doesn't have to do much with firing more rays than handling more complex materials; what I just described decouples diffuse/specular and is how games are doing it these days. But if the current materials are plausible, then what's wrong with this approach? I do think it is the/a right approach... when used judiciously and when an alternative rasterization approach doesn't already exist or has obvious flaws. For example, some games use a hybrid SSR-RT reflection; do the SSR first, then fire rays where the SSR misses (insufficient information in screen-space.) I think the UE5 Matrix demo does this. You kind of get the best of both approaches. The article in this sense proposes a false dichotomy; to choose between the complex "hacks" of rasterization, or the easiness of RT. Except that rasterization has decades of research and solutions are well-known and already implemented, and RT is not 'do the dumb thing and let the hardware do the work'. I don't think BVH construction is as bad as your friend paints it. There are semi-parallel approaches available, i.e. https://www.researchgate.net/publication/327216026_PLOCTree_A_Fast_High-Quality_Hardware_BVH_Builder https://www.researchgate.net/publication/327216026_PLOCTree_...