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Physically based rendering is _not_ the Disney shader and renaming your diffuse maps to albedo because it sounds more sciencey. It’s about the wholesale switch

Physically based rendering is _not_ the Disney shader and renaming your diffuse maps to albedo because it sounds more sciencey. It’s about the wholesale switch to a fully path-traced framework with a consistent mathematical foundation as opposed to the layered system of hacks and chained prepasses that prevailed in the early 2000’s

jasonwatkinspdx 9y ago
This. You can use PBR concepts in an old school renderman style pipeline, but that's not why it's been a big deal in VFX. With a PBRT style renderer, everything is handled in a single monte carlo framework. And once you get an unbiased renderer that meets your standards, you can implement schemes like irradiance caching or photon mapping that introduce bias, but greatly accelerate rendering (and reduce noise). That optimization can be done once, for everything past and future. That's why I'm saying the combination of PBR and tracing is a huge productivity boon to both sides, art and tech. It has a performance cost, but if/when hardware can pay that cost in real time, games absolutely will use it.
- ksec 9y ago
  >It has a performance cost, but if/when hardware can pay that cost in real time, games absolutely will use it. Which has been said since earl6 2000. But the question is, when? Or if it will ever come? If you look at road maps we surely dont have that in next 5 years, even unlikely in 10.
- hvidgaard 9y ago
  With 4K around for corner for regular gamer screens, and top of the line GPUs that cannot handle that at an acceptable speed yet, I think it's a long time before we see that. Maybe when a 200$ GPU can do 4K 60 fps, but until then 5-10% gain is seen as worth chasing.
  - kevingadd 9y ago
    Every pass doesn't have to be rendered at native resolution, and most aren't. When you're running a game at 4K on your PS4 pro or modern PC, very often the 4K image is being produced using a mix of temporal anti-aliasing (accumulating a full image over time across multiple frames), heuristic upsampling, etc. Many post-processing passes run well below screen resolution even if you're running at 1080p - things like SSAO and even particle effects are typically rendered at a lower resolution. Also, many modern games have been hitting 60fps at 4k on mid-high tier cards for years - you can hit 60 at 4k with reasonable quality settings in a game like MGS5 or GTA5 on a single 970. If you get a 1080 way more stuff runs great, even at higher settings. Many modern games have an internal resolution slider as well, so you can set the internal resolution to 80 or 90% and still get your UI rendered at full 4K resolution. If the game has temporal anti-aliasing the difference tends to be hard to spot. Finally, if you've got a freesync or gsync monitor, a few dips down to 50fps at 4k aren't going to be super noticeable, and the games look great. :)
- pzone 9y ago
  Actually PBR is quite a very important workflow innovation in rasterizing engines, see my post above!
- psandersen 9y ago
  Worth adding that if we get more hardware support for deep neural networks on the GPU (e.g. tensor cores), training a denoising DNN on the noisy renders can save a lot of computation and fits neatly into the pipeline. If the ray tracing can be done at or around 1 ray per pixel or less using a network trained to do merge information over multiple frames and upscale we could probably get away with less. Maybe more if we can feed in a depth map, velocity map and a flat shader less rendering or other information to help guide the DNN. Might even end up faster than current raster renders. See https://www.chaosgroup.com/blog/experiments-with-v-ray-next-using-the-nvidia-optix-denoiser https://www.chaosgroup.com/blog/experiments-with-v-ray-next-...
pzone 9y ago
That's not really what it's about! It's not about achieving physical correctness or ray tracing. You can have a PBR renderer selectively break energy conservation for artistic reasons. It's not about ray tracing either. Current game engines like Unreal and Unity are considered PBR because they use a roughness/metalness workflow. PBR about having maps that are easy to understand through physical analogy, and simplifying the workflow so that it's mostly shared across render engines, applications and pipelines. It's about the ability to create texture in Mari or Substance, which use rasterizing engines, and seeing the final render in Arnold look nearly identical.

jasonwatkinspdx 9y ago

This. You can use PBR concepts in an old school renderman style pipeline, but that's not why it's been a big deal in VFX. With a PBRT style renderer, everything is handled in a single monte carlo framework. And once you get an unbiased renderer that meets your standards, you can implement schemes like irradiance caching or photon mapping that introduce bias, but greatly accelerate rendering (and reduce noise). That optimization can be done once, for everything past and future. That's why I'm saying the combination of PBR and tracing is a huge productivity boon to both sides, art and tech. It has a performance cost, but if/when hardware can pay that cost in real time, games absolutely will use it.

ksec 9y ago
>It has a performance cost, but if/when hardware can pay that cost in real time, games absolutely will use it. Which has been said since earl6 2000. But the question is, when? Or if it will ever come? If you look at road maps we surely dont have that in next 5 years, even unlikely in 10.
hvidgaard 9y ago
With 4K around for corner for regular gamer screens, and top of the line GPUs that cannot handle that at an acceptable speed yet, I think it's a long time before we see that. Maybe when a 200$ GPU can do 4K 60 fps, but until then 5-10% gain is seen as worth chasing.
- kevingadd 9y ago
  Every pass doesn't have to be rendered at native resolution, and most aren't. When you're running a game at 4K on your PS4 pro or modern PC, very often the 4K image is being produced using a mix of temporal anti-aliasing (accumulating a full image over time across multiple frames), heuristic upsampling, etc. Many post-processing passes run well below screen resolution even if you're running at 1080p - things like SSAO and even particle effects are typically rendered at a lower resolution. Also, many modern games have been hitting 60fps at 4k on mid-high tier cards for years - you can hit 60 at 4k with reasonable quality settings in a game like MGS5 or GTA5 on a single 970. If you get a 1080 way more stuff runs great, even at higher settings. Many modern games have an internal resolution slider as well, so you can set the internal resolution to 80 or 90% and still get your UI rendered at full 4K resolution. If the game has temporal anti-aliasing the difference tends to be hard to spot. Finally, if you've got a freesync or gsync monitor, a few dips down to 50fps at 4k aren't going to be super noticeable, and the games look great. :)
pzone 9y ago
Actually PBR is quite a very important workflow innovation in rasterizing engines, see my post above!
psandersen 9y ago
Worth adding that if we get more hardware support for deep neural networks on the GPU (e.g. tensor cores), training a denoising DNN on the noisy renders can save a lot of computation and fits neatly into the pipeline. If the ray tracing can be done at or around 1 ray per pixel or less using a network trained to do merge information over multiple frames and upscale we could probably get away with less. Maybe more if we can feed in a depth map, velocity map and a flat shader less rendering or other information to help guide the DNN. Might even end up faster than current raster renders. See https://www.chaosgroup.com/blog/experiments-with-v-ray-next-using-the-nvidia-optix-denoiser https://www.chaosgroup.com/blog/experiments-with-v-ray-next-...

pzone 9y ago

That's not really what it's about! It's not about achieving physical correctness or ray tracing. You can have a PBR renderer selectively break energy conservation for artistic reasons. It's not about ray tracing either. Current game engines like Unreal and Unity are considered PBR because they use a roughness/metalness workflow. PBR about having maps that are easy to understand through physical analogy, and simplifying the workflow so that it's mostly shared across render engines, applications and pipelines. It's about the ability to create texture in Mari or Substance, which use rasterizing engines, and seeing the final render in Arnold look nearly identical.