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The hardware raytracing support is a huge step in the right direction for real time graphics. The shaky jenga tower of hacks on top of the rasterization pipelin

The hardware raytracing support is a huge step in the right direction for real time graphics. The shaky jenga tower of hacks on top of the rasterization pipeline that is in the current generation of rendering engines is barely sustainable. Fast raytracing provides an alternative that is much closer to the actual physical model of light transport in the real world and does not require as many nasty approximations and cheats as rasterization for the same quality. Mind you that you are seeing the early generation of hardware based real time raytracing now and it already can beat the quality of rasterization. There is still a ton of room for improvements. One or two hardware generations from now we may finally see realtime generated images for which the term photorealistic is not just a silly marketing hype. They could truly fool you.

saiya-jin 8y ago
For a gamer, Nvidia's latest card offering is vastly disappointing. Technology that is not there and won't be there for maybe next 6 years (if they stick to 3 year release cycle), offering some shiny surfaces at best, at massively increased price. I really hope AMD will come with some good cheaper competition. Gamers want fast framerates, high polygon count, high textures much more than some currently-useless raytracing. Solve those into near-reality quality in at least 1440p resolution, and then we can talk about these gimmicks. I'll happily skip this (and next) gen and will be OK with some 1080 card.
- gmueckl 8y ago
  I don't get the ridiculous pricing of the current generation of nVidia chips, either. But this generation of hardware is at the same time an important step towards getting rendering algorithms that have vastly superior quality while having a much simpler structure. I know that anybody that works on high quality real time renderers and knows what they are doing wants this switch to happen.
  - ahartmetz 8y ago
    Heck, I've only read papers about most rasterization based "realism" tricks and I want this switch to happen. Polemically speaking, current realtime rendering pipelines are based on sprite rotoscalers and the end user being too busy to notice the errors. Raytracing is based on how light works.
    - gmueckl 8y ago
      The literature conveniently neglects to mention how fiddly and difficult it is to implement that stuff reliably. Debugging the rendering pipeline is not exactly easy, especially when the data is not just positions and colors, but more abstract stuff. Also, there's tons of edge cases that need hacks and workarounds, crazy driver bugs etc...
  - ksec 8y ago
    Buying an 800mm2 Die along with 12GB GDDR6 Memory for $999 isn't really ridiculous. Try getting Intel or AMD to sell you an 800mm2 CPU Die for $999. As a matter of fact I thought it was reasonably priced in terms of Die Size and Transistors. Now whether those 800mm2 perform up to our expectation is an entirely different matter.
- namibj 8y ago
  Honestly, once we have a suitable HMD (aka. VR goggles), we can use a cluster of raytracers to experiment with actual photorealistic reality. My previous best guess would have been a clustered version of Luxrender, but most recent projections of mine yielded ~20MW of current-gen CPU cluster (with a hint of GPU (about 3:1 electrical CPU:GPU) to offload ray intersection for a 2~3x speed boost) as what would be needed to feed a display that can reach the far end of uncanny valley as far as the visuals themselves go. This would be _expensive_ and quite likely considered a useless waste of computing, but I seriously think we should try to get to the point where we can do this. And it truly requires ray tracing to handle the vast amount of detail the scene would require. Also testing scales much better down to a workstation for photorealism than for textured and shaded polygon technology. The main reason is just that most of ray tracing is parallel, save for sequential tracing of each individual ray. The result is that much more of the behavior is scale-free which enables you to test materials much quicker/more interactively than with shaded polygons. The other part of that is how a material's behavior doesn't depend on other/nearby objects as much, so you can mock those better and have few surprises as far as their interaction is concerned. Luxrender specifically was used years ago for such things as rendering imaged for a iirc. perfume bottle catalogue, as it was easier to specify the material properties and adapt for the colors/opacities and label prints than to get regular, symmetrical photos from a photographer in a studio. The requirement was that the realism allowed skipping a disclaimer about the images not being photographs. And that implies confidence in the mathematical models used in the "simulation". RTX cards might allow porting Luxrender in a way that retains it's spectral treatment that actually physically simulated a dispersive prism generating a rainbow from a ray of white light, without more than specifying the dispersion of the glass. It goes without saying that such effects are inherently very noisy, but there might be ways using automatic differentiation (c.f. Julia (language)) combined with advanced numerical integration to make use of calculus to reduce the noise in individual samples. If anyone knows about attempts to combine Metropolis light transport (MLT) with automatic differentiation or just about a more concrete idea to incorporate advanced numerical integration with MLT, or a potentially suitable MLT implementation in Julia, please let me know, i'd like to check it out and actually consider it a suitable "toy" project for learning Julia. The ease of efficient GPU use from this high level just allows so much flexibility in e.g. complex material node graphs getting handled with no extra work on the integrator then.
atq2119 8y ago
The currently available generation of hardware based real time raytracing cannot beat the quality of rasterization at the same framerates. NVidia built a cool bit of hardware, but their media blitz was seriously misleading. It's much faster than anything you can do on earlier hardware, but that doesn't mean it's actually fast yet for general game engines. One of the problems is that raytracing is inherently noisy, so you actually have to shoot many rays (or trace many paths) for each pixel on the screen, and you really need to get into the high double digits for acceptable results purely from raytracing. Part of NVidia's sales pitch is that you can reduce the number of samples / rays using advanced post-processing filters based on CNNs. But then you're back to building a jenga tower of hacks, just this time on top of raytracing instead of on top of rasterization. You may prefer the raytracing jenga tower perhaps, but truth in advertisement should make it clear that raytracing alone just isn't there yet. It's true though that this current generation of hardware is promising, and things are bound to get better quickly. For now, the most you're going to get is hybrid techniques where rasterization is used for the bulk of the rendering, and raytracing is used selectively e.g. for parts of a scene or for shadows.
- gmueckl 8y ago
  I personally know some of the guys who developed the CNN based denoising. This stuff really works and it is actually pretty simple to implement compared to the truly horribly complicated hacks that you need to get e.g. realtime reflections even remotely to a level that is not outright jarring and obviously wrong looking. What has me worried is not the performance of the ray-scene intersection, but the dynamic BVH update that is required for each frame. Building acceleration structures for ray intersection tests is a hard tradeoff between fast construction times and fast intersection tests. With animated/deforming objects, this is quite an interesting challenge. But we might eventually see some dedicated hardware for that, too. Academic implementations exist.

saiya-jin 8y ago

For a gamer, Nvidia's latest card offering is vastly disappointing. Technology that is not there and won't be there for maybe next 6 years (if they stick to 3 year release cycle), offering some shiny surfaces at best, at massively increased price. I really hope AMD will come with some good cheaper competition. Gamers want fast framerates, high polygon count, high textures much more than some currently-useless raytracing. Solve those into near-reality quality in at least 1440p resolution, and then we can talk about these gimmicks. I'll happily skip this (and next) gen and will be OK with some 1080 card.

gmueckl 8y ago
I don't get the ridiculous pricing of the current generation of nVidia chips, either. But this generation of hardware is at the same time an important step towards getting rendering algorithms that have vastly superior quality while having a much simpler structure. I know that anybody that works on high quality real time renderers and knows what they are doing wants this switch to happen.
- ahartmetz 8y ago
  Heck, I've only read papers about most rasterization based "realism" tricks and I want this switch to happen. Polemically speaking, current realtime rendering pipelines are based on sprite rotoscalers and the end user being too busy to notice the errors. Raytracing is based on how light works.
  - gmueckl 8y ago
    The literature conveniently neglects to mention how fiddly and difficult it is to implement that stuff reliably. Debugging the rendering pipeline is not exactly easy, especially when the data is not just positions and colors, but more abstract stuff. Also, there's tons of edge cases that need hacks and workarounds, crazy driver bugs etc...
- ksec 8y ago
  Buying an 800mm2 Die along with 12GB GDDR6 Memory for $999 isn't really ridiculous. Try getting Intel or AMD to sell you an 800mm2 CPU Die for $999. As a matter of fact I thought it was reasonably priced in terms of Die Size and Transistors. Now whether those 800mm2 perform up to our expectation is an entirely different matter.
namibj 8y ago
Honestly, once we have a suitable HMD (aka. VR goggles), we can use a cluster of raytracers to experiment with actual photorealistic reality. My previous best guess would have been a clustered version of Luxrender, but most recent projections of mine yielded ~20MW of current-gen CPU cluster (with a hint of GPU (about 3:1 electrical CPU:GPU) to offload ray intersection for a 2~3x speed boost) as what would be needed to feed a display that can reach the far end of uncanny valley as far as the visuals themselves go. This would be _expensive_ and quite likely considered a useless waste of computing, but I seriously think we should try to get to the point where we can do this. And it truly requires ray tracing to handle the vast amount of detail the scene would require. Also testing scales much better down to a workstation for photorealism than for textured and shaded polygon technology. The main reason is just that most of ray tracing is parallel, save for sequential tracing of each individual ray. The result is that much more of the behavior is scale-free which enables you to test materials much quicker/more interactively than with shaded polygons. The other part of that is how a material's behavior doesn't depend on other/nearby objects as much, so you can mock those better and have few surprises as far as their interaction is concerned. Luxrender specifically was used years ago for such things as rendering imaged for a iirc. perfume bottle catalogue, as it was easier to specify the material properties and adapt for the colors/opacities and label prints than to get regular, symmetrical photos from a photographer in a studio. The requirement was that the realism allowed skipping a disclaimer about the images not being photographs. And that implies confidence in the mathematical models used in the "simulation". RTX cards might allow porting Luxrender in a way that retains it's spectral treatment that actually physically simulated a dispersive prism generating a rainbow from a ray of white light, without more than specifying the dispersion of the glass. It goes without saying that such effects are inherently very noisy, but there might be ways using automatic differentiation (c.f. Julia (language)) combined with advanced numerical integration to make use of calculus to reduce the noise in individual samples. If anyone knows about attempts to combine Metropolis light transport (MLT) with automatic differentiation or just about a more concrete idea to incorporate advanced numerical integration with MLT, or a potentially suitable MLT implementation in Julia, please let me know, i'd like to check it out and actually consider it a suitable "toy" project for learning Julia. The ease of efficient GPU use from this high level just allows so much flexibility in e.g. complex material node graphs getting handled with no extra work on the integrator then.

atq2119 8y ago

The currently available generation of hardware based real time raytracing cannot beat the quality of rasterization at the same framerates. NVidia built a cool bit of hardware, but their media blitz was seriously misleading. It's much faster than anything you can do on earlier hardware, but that doesn't mean it's actually fast yet for general game engines. One of the problems is that raytracing is inherently noisy, so you actually have to shoot many rays (or trace many paths) for each pixel on the screen, and you really need to get into the high double digits for acceptable results purely from raytracing. Part of NVidia's sales pitch is that you can reduce the number of samples / rays using advanced post-processing filters based on CNNs. But then you're back to building a jenga tower of hacks, just this time on top of raytracing instead of on top of rasterization. You may prefer the raytracing jenga tower perhaps, but truth in advertisement should make it clear that raytracing alone just isn't there yet. It's true though that this current generation of hardware is promising, and things are bound to get better quickly. For now, the most you're going to get is hybrid techniques where rasterization is used for the bulk of the rendering, and raytracing is used selectively e.g. for parts of a scene or for shadows.

gmueckl 8y ago
I personally know some of the guys who developed the CNN based denoising. This stuff really works and it is actually pretty simple to implement compared to the truly horribly complicated hacks that you need to get e.g. realtime reflections even remotely to a level that is not outright jarring and obviously wrong looking. What has me worried is not the performance of the ray-scene intersection, but the dynamic BVH update that is required for each frame. Building acceleration structures for ray intersection tests is a hard tradeoff between fast construction times and fast intersection tests. With animated/deforming objects, this is quite an interesting challenge. But we might eventually see some dedicated hardware for that, too. Academic implementations exist.