Ray tracing is a term you’re going to hear a lot now that Nvidia has announced professional and consumer graphics cards that use this technique to produce some of the most life-like simulations possible in games and other animations. So, what is ray tracing exactly, and how does it differ from current graphics rendering techniques?
The oversimplified answer is that ray tracing models the behavior of light in real time as it intersects objects in a scene.
It’s a feature that could lead to spectacular new graphics, but has been very hard to pull off because of the computational requirements. But Nvidia is tackling several issues facing ray tracing with a new graphics architecture known as Turing.
Turing is the biggest jump in graphics since CUDA arrived in 2006
First, it’s tackling the problem of ushering in the next generation of computer graphics. Ray tracing is only one of many rendering techniques, but it’s where Nvidia is pushing hard because it’s especially suited for adding realistic, real-time lighting and effects.
The second issue is computational cost: the best Turing card for professional production costs $10,000, but it was even costlier to use ray tracing before. What’s new here is Nvidia is ready to bring ray-tracing tech to consumer-level GPUs; that hasn’t been done before.
Nvidia’s current graphics tech — and most of the industry’s — simulates light and how light behaves in a given scene in a much simpler way, using something called rasterization. Like a painter painting layers upon a canvas, objects are rendered from back to front, so those in the front obscure the objects in the back.
This makes it hard to model a mirror, for example, because rasterization techniques can’t track and model light itself. It’s used often in real-time scenes because current-generation hardware can’t keep up with the demands of simulating a complex scene in motion for something that requires it (say, a game or 3D animation).
Ray tracing models the behavior of light as it intersects objects
This next generation of light simulations can model light in much more detail, without as much computational cost as before. Ray tracing models the behavior of light as it intersects with surfaces, materials, and moving objects.
A path of light that travels through a scene can be rendered more intricately now. With ray tracing, you could simulate how rays of light interact with objects, producing realistic reflection, refraction, and scattering effects in real time. Ray tracing can even detect and render mirrors, refract glass, figure out where light in a scene originates, and even determine the color of light as it passes through objects.
On paper, it sounds like the rendering technique is almost too realistic, but it’s not exactly new. Ray tracing has been used in the professional industry for years. It’s already been employed in popular media, like Pixar’s Monsters University and Marvel’s Iron Man movies. What makes the announcement exciting is it will finally be available for consumer hardware; a feat that was too difficult and expensive before.
Here’s an example of ray tracing working in real time during a Star Wars demo, using Nvidia’s professional Volta RTX graphics cards:
What kept Nvidia back from accomplishing this sort of feat for consumers is that ray tracing requires an incredible amount of computational power. Nvidia CEO Jensen Huang said this is “the single greatest leap that we have ever made in one generation.”
It makes sense, considering the new Turing architecture used in Nvidia’s new GPUs is designed to address the processing issue. Dedicated ray-tracing cores work in conjunction with Tensor Cores — they use AI to infer the “real-time” part — to produce simulations six times faster than the previous Pascal platform (GTX 1080Ti, etc.).
Ray tracing has use everywhere in computer graphics
It’s a big jump in graphics tech and is exciting when you think about the studios and individuals that will find new uses for ray tracing in animation, games, and science simulations.
Even if the new hardware Nvidia produces will only be available for desktops first, laptops with ray-tracing tech will start coming to market next year, so they’re not too far off. In fact, certain upcoming games like Metro: Exodus already have Nvidia RTX demos showing off real-time ray tracing doing its thing.