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The currently available generation of hardware based real time raytracing cannot beat the quality of rasterization at the same framerates. NVidia built a cool b

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.

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.