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There are many other changes happening in the rendering world. Two others are: - More accurate calculations based on the physics of the light in the scene (i.e

by troymc 15y ago

There are many other changes happening in the rendering world. Two others are: - More accurate calculations based on the physics of the light in the scene (i.e. techniques which tend to produce more "real-looking" renders). Ideas for how to do this aren't new, but the available computing has increased and made some of those ideas practical. - The use of GPU clusters for rendering. This may sound odd to gamers, who might think GPUs have always been used for rendering, but the real-time rendering done for video games is different from the rendering done for high-end movies and architectural visualization. Until recently, those rendering calculations were done by CPUs, but with the advent of general-purpose computing on GPUs (GPGPU), and standard ways to do that (CUDA and OpenCL), there's been an increase in the use of GPUs for rendering.

radarsat1 15y ago
I was wondering about GPUs, after reading that sentence about "massive farm of CPU cores." GPU processing is here now, and I'd be surprised if the movie-quality rendering industry, who stand to benefit hugely from increases in speed, haven't explored this option yet. Especially as both GPGPU APIs have special structures and functions to help with graphics-related tasks like image loading, handling colours, etc. On the other hand, I could see some difficulties: a lot of cards don't yet support 64-bit floats, and there are some severe memory restrictions. However, with a card on the expensive side, you can get can around both these problems, and it really will render the scene thousands of times faster than a CPU so the cost would pay off. Something like the NVidia Testla "personal supercomputers" are "only" on the order of 8000$ or so for 6 GB of video RAM and just an amazing number of cores available, a drop in the bucket for a company whose revenue depends solely on rendering graphics.
- berkut 15y ago
  The reasons GPUs aren't yet used much in the VFX industry, are: GPUs are currently limited by what they can do - they're fast in terms of float throughput in a simple loop, but as soon as you introduce a lot of branching (for things like global illumination - path tracing), their throughput falls off a lot. The Fermis are better, but Intel's branch predictors are very good. SSE and AVX can also more than quadruple the throughput of CPUs in the best of cases. Also, a typical VFX feature film scene can have up to 200GB of geometry and 100 GB of textures, and this is before acceleration structures, deformation motion blur caches and texture mip-maps have been created. Transferring that amount of data through the PCI-E bus isn't worth it at the moment, especially given the limit of 6GB of onboard VRAM that would mean huge amounts of swapping. Also, GPUs use even more power and produce even more heat than CPUs, so you don't save anything here.
  - Keyframe 15y ago
    One other reason why GPUs aren't as widely used: Primary Rays Cache, Secondary Rays Trash! GPUs are becoming a standard in some pipeline stages of rendering though. http://www.nvidia.com/object/wetadigital_avatar.html http://www.nvidia.com/object/wetadigital_avatar.html
    - berkut 15y ago
      That's Weta being weird and being wed to their PRMan pipeline using PantaRay as a first-stage radiosity solution which is fed to PRMan as an infinite series of lights. It works, but from what I hear it's limiting their pipeline quite a bit. But then, they're Weta so they're more than capable of writing their own stuff and they're good at what they do :) ILM used to do something similar, but a lot of the big houses are moving from PRMan over to raytracers (specifically Arnold) with full GI support as it makes the overall pipeline and definitely artist look-dev a lot simpler and faster. PRMan 16 is also a very good raytracer now (it could previously do ray tracing through custom shaders).

by troymc 15y ago

radarsat1 15y ago

I was wondering about GPUs, after reading that sentence about "massive farm of CPU cores." GPU processing is here now, and I'd be surprised if the movie-quality rendering industry, who stand to benefit hugely from increases in speed, haven't explored this option yet. Especially as both GPGPU APIs have special structures and functions to help with graphics-related tasks like image loading, handling colours, etc. On the other hand, I could see some difficulties: a lot of cards don't yet support 64-bit floats, and there are some severe memory restrictions. However, with a card on the expensive side, you can get can around both these problems, and it really will render the scene thousands of times faster than a CPU so the cost would pay off. Something like the NVidia Testla "personal supercomputers" are "only" on the order of 8000$ or so for 6 GB of video RAM and just an amazing number of cores available, a drop in the bucket for a company whose revenue depends solely on rendering graphics.

berkut 15y ago
The reasons GPUs aren't yet used much in the VFX industry, are: GPUs are currently limited by what they can do - they're fast in terms of float throughput in a simple loop, but as soon as you introduce a lot of branching (for things like global illumination - path tracing), their throughput falls off a lot. The Fermis are better, but Intel's branch predictors are very good. SSE and AVX can also more than quadruple the throughput of CPUs in the best of cases. Also, a typical VFX feature film scene can have up to 200GB of geometry and 100 GB of textures, and this is before acceleration structures, deformation motion blur caches and texture mip-maps have been created. Transferring that amount of data through the PCI-E bus isn't worth it at the moment, especially given the limit of 6GB of onboard VRAM that would mean huge amounts of swapping. Also, GPUs use even more power and produce even more heat than CPUs, so you don't save anything here.
- Keyframe 15y ago
  One other reason why GPUs aren't as widely used: Primary Rays Cache, Secondary Rays Trash! GPUs are becoming a standard in some pipeline stages of rendering though. http://www.nvidia.com/object/wetadigital_avatar.html http://www.nvidia.com/object/wetadigital_avatar.html
  - berkut 15y ago
    That's Weta being weird and being wed to their PRMan pipeline using PantaRay as a first-stage radiosity solution which is fed to PRMan as an infinite series of lights. It works, but from what I hear it's limiting their pipeline quite a bit. But then, they're Weta so they're more than capable of writing their own stuff and they're good at what they do :) ILM used to do something similar, but a lot of the big houses are moving from PRMan over to raytracers (specifically Arnold) with full GI support as it makes the overall pipeline and definitely artist look-dev a lot simpler and faster. PRMan 16 is also a very good raytracer now (it could previously do ray tracing through custom shaders).