1. The highly-parallelizable nature of RT is ideal for many-core architecture we're heading toward. Note that the PowerVR hardware used in the demo has 4 cores, needs no fans, and uses 10x less power than a traditional rasterization-optimized GPU.
2. The simplicity of implementing physically-based effects leads to a much easier time for artists.
[1] http://blog.selfshadow.com/publications/s2012-shading-course...
[2] http://blog.selfshadow.com/publications/s2015-shading-course...
If the former, then maybe a bit.
But the beauty of physically-based is that in many cases, you can take a model that's been textured and lookdeved and it will work nicely in many different lighting setups. Before Physically-based, you practically had to re-do stuff completely when you changed the lighting to get the look you wanted.
However, Physically-based still isn't a complete win - you can't looked something close up and expect it to look good in the distance - it just won't. You need to be aware of the LODs and create different asset variations appropriately for different distances.
http://www.zeitguised.com/geistxyz#geistxyz01 https://vimeo.com/150824660
The problem that occurs when trying to do path tracing on current hardware is that secondary (reflected) rays are incoherent so the gpu will stall one ray while waiting for another that hit something, leading to poor utilization of the gpu. It's still normally faster than on a cpu, but compared to "simpler" problems like some linear algebra (Machine Learning or similar) the perf of gpu vs cpu is low.
For real GI, Path Tracing, Photon Mapping and so on are the methods of choice and not Ray Tracing.
Global illumination is where we want to go to surpass the realism of current games, but path tracing and photon mapping are both fundamentally based on ray-tracing. Any hardware that makes ray-tracing go faster (especially for incoherent rays) should also help to speed up global illumination.
Depending on the implementation, raytracing can have many benefits over rasterization, such as: - ability to produce pixel-perfect shadows - sub-linear complexity on the amount of primitives (vs. linear for rasterization) - rays need not be coherent, i.e one can render non-linear projections or lots of small views
Path Tracing also is just another form of Raytracing. They demonstrated that their hardware can be used for it (just read the link).
The chip iterates on "standard" GPU designs made to performed rasterization, therefore it has everything in place to launch compute jobs or do tessellation. In addition, they have some additional hardware for raytracing. From one of the previous GDC presentations it was more or less clear that you could programmatically activate raytracing with a configurable number of rays and those rays will deliver additional lighting contributions to the objects of the scene.
As you get closer to that in real time you get to the point where VR will give you out of body experiences.
>Just point the magic gizmo at your geometry and "poof" perfectly lit scene.
There are plenty of global illumination models that do not require doing full path tracing e.g. Radiosity https://en.wikipedia.org/wiki/Radiosity_(computer_graphics) which are much more efficient than ray tracing (even on dedicated RT hardware fyi) while resulting in pretty much an identical image, path tracing also works pretty damn well. One of the main reasons that these aren't use isn't because the current hardware isn't fast enough but because the resulting image just doesn't look right because of various factors and has to be then highly adjusted to increase it's dynamic range. Global illumination creates brilliant results when your eye perceive it as "real" illumination like for example when sitting in a dark cinema when the only light source is the light bouncing from the screen which means your eyes only adjust to the brightness level of various areas in the screen which allows it to maintain relatively high dynamic range even tho it's pretty much uniformally lit.
With computer monitors this simply doesn't work the monitor is most cases isn't the brightest object in the room as you have both day light and indoor lighting. The monitor in most cases doesn't take as nearly as much of your view as a movie screen does and modern cinema projection solutions can actually provide high dynamic range by having different luminosity levels for different parts of the screen while your monitor is lit by a single diffused light source.
This pretty much means when you use global illumination you get much much lower contrast between lit and shadowed areas as well as overall darker lights and lighter shadows. Sure the scene is universally lit but it just doesn't look like what people expect partially because they are used to direct illumination as it has been mostly used (with a few exceptions mostly due to the issues brought up here) for the past 20 years of real time 3D graphics.
So when you do use global illumination models (doesn't matter if they are precomputed like Valve's implementation of Radiosity, DICE's real time RS, or Nvidia's Gameworks Path Tracing) you either get a really washed out look or you have to tweak the hell out of it during post processing to give it a more stylized look.
And again Ray Tracing doesn't save you from shaders you still need to write the same material shaders as you do today some of them might be slightly simplified if you are doing various things like fetching different specular/reflection maps based on the viewport or scene composition etc. But overall you will still have the same shaders that make one door look like glass while the other like wood because it's silly to have to make 2 doors when you can just adjust a flag in a shader.
I really don't understand why are they chasing RT.
Also would be nice to know how well they can actually compute shaders, do tessellation and many other things because this is one heck of a fluff piece and I can remember at least 1 of these past 20 years that proclaimed that real time RT in hardware is here.