That’s where ray-tracing comes in. Light rays are projected from the pixels or light source, depending on the algorithm, then bounce around the scene until they hit the camera or light source. This is exactly how we see things — photons bounce off and through objects, have their wavelengths changed, and eventually hit our eyes. As we explained earlier this year, dedicated ray-tracers render VFX scenes realistically enough to be inserted into live-action movies.
However, all these photons bouncing around saturate your GPU pretty quickly. Ray-tracing is fine for movie post-production facilities, which have hundreds of servers to render things. It’s not ideal for games, though, where limited hardware must render a frame in 1/60th of a second. That’s where NVIDIA’s RTX comes in, as it can execute ray-tracing computations with far greater speed than ever before.
Ray-tracing will not take over how your games render graphics anytime soon. Doing full ray-traced rendering is still well beyond any graphics card, even NVIDIA’s $10,000 Quadro RTX 8000. Mostly, they’ll be used alongside existing raster engines to enhance certain effects, like reflections and shadows.
Giga rays and RTX-OPS
To put a number to these new specialised cores, NVIDIA is now emphasizing giga rays and RTX-OPS. While the GeForce GTX 1080 Ti puts out a mere 1.21 giga rays per second, Turing GPUs can power through 10 giga rays per second — up to eight times quicker.
Meanwhile, using a hybrid measurement that combines ray-tracing and floating point operations, the Turing-powered GTR 2080 Ti can handle 78 RTX-OPS compared to 12 RTX-OPS for the 1000-series Pascal generation. That’s the six-fold increase we’ve seen trumpeted around the internet.
Jensen Huang said that such progress “has simply never happened before; a supercomputer replaced by one GPU in one generation.” The demos he showed off at Gamescom, especially Project Sol (above) that showed robots and an Iron Man-like suit, were the most impressive real-time ray-tracing videos we’ve ever seen, considering they ran on a single GPU (the $6,300 Quadro RTX 6000).
Demos versus the real world
However, don’t expect games to look instantly better with RTX cards. To see any benefit beyond the theoretical 30 to 40 percent boost, games will need to be designed specifically to take advantage of ray-tracing. None are available at the moment, and just two that we know of are coming down the pipe — Battlefield V and Shadow of the Tomb Raider.
NVIDIA’s RTX does use Microsoft’s new DirectX feature called DXR, also supported by AMD via its Radeon Rays feature. And Microsoft has said that DXR will work just fine on current-generation and older graphics cards. However, NVIDIA has strongly implied that it won’t be very useful without its next-gen cards and that past models, even the GTX 1080 Ti, will do the operations too slowly.
NVIDIA also said that its DLSS AI feature will boost game speeds by up to two times. To do that, the RTX tensor cores will take over anti-aliasing (AA) that normally consumes a lot of GPU cycles and memory resources. DLSS is a specific NVIDIA function that will have to be coded game-by-game, but NVIDIA will do it for free if developers send them the code.
GameWorks and the graveyard of lost GPU tech
There has been a lot of hype over GPU tech that never panned out as it was supposed to. Take AMD’s Mantle and, most recently, GameWorks. Much of this tech didn’t bring the promised gaming speed or quality improvements, yet the cards were sold in part on those features.
Any game-improvement features are especially suspect if they’re limited to one brand or another, as appears to be the case with NVIDIA’s DLSS and some RTX functions. The reason is obvious. Game developers don’t want to favor one GPU platform over another, as it stretches their already-thin resources and often results in bad press and unhappy buyers if it doesn’t deliver.
For instance, NVIDIA introduced GameWorks middleware to help developers create better hair, fur, physics and other effects. However, the features were optimized for NVIDIA cards, and running them on an AMD GPU often lead to bad or unpredictable performance — and GameWorks proved to be problematic even on NVIDIA’s own cards. NVIDIA brought it up during the RTX launch earlier this year, but we haven’t heard much about GameWorks for the RTX 2000-series cards.
Spend or wait?
Buying into a new graphics system based on unproven tech, especially something as complex as ray-tracing, is a pretty big risk. It doesn’t help that the new RTX 2080 Ti card is expensive and power-hungry, and doesn’t offer amazing speed improvements on paper. It might indeed have a superior architecture that overcomes the specs, but it’s worrying that NVIDIA spent so much time describing the ray-tracing tech and very little showing how it improves games you can play right now.
It’ll be great if RTX ray-tracing and AI improves future games as promised, but given the two year or so hardware upgrade cycle, NVIDIA might have moved on to other things by the time they come along. All we’ve got to go on right now are the specs and NVIDIA’s word about performance. Until testing and reviews make the picture clearer, you might want to wait and see how it all shakes out.
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