What is Ray Tracing and Why Do You Want it in Your GPU?

[kcarbotte]

Nvidia's new Tesla chips can handle ray tracing in real time. Here's what that means for the future of gaming and animation.

What is Ray Tracing and Why Do You Want it in Your GPU? : Read more

 

[Martell1977]

I would surmise that this will be especially important in VR games/programs. I wonder what effect this new design will have on power consumption and if it will be overclockable as part of OCing the GPU core, individually or even at all.

AMD's response to this should make things interesting.

 

[bloodroses]

So, current graphics are raster based. Now that real-time ray tracing is coming, will graphics completely switch to that or will they be a hybrid of it?

What's really kind of interesting is that Intel's Larabee was a flop because it couldn't handle raster graphics well. Ray-tracing was a different story though. With the acquisition of ex-AMD employee Raja Koduri, they could be in a good position to become a major GPU threat.

 

[ingtar33]

I was under the impression that Vega supported ray tracing.

 

[bit_user]

So, current graphics are raster based. Now that real-time ray tracing is coming, will graphics completely switch to that or will they be a hybrid of it?

Nvidia already announced hybrid techniques, such as RT-based anti-aliasing. Plus, there's the obvious possibility of using RT just for certain aspects like indirect illumination and reflection.

 

[bit_user]

I was under the impression that Vega supported ray tracing.

All GPUs can do it in software, but not very fast (better than CPUs, but still not good enough for pure raytraced gaming).

As far as we know, Vega has no hardware engine like the RT cores.

 

[jimmysmitty]

So, current graphics are raster based. Now that real-time ray tracing is coming, will graphics completely switch to that or will they be a hybrid of it?

What's really kind of interesting is that Intel's Larabee was a flop because it couldn't handle raster graphics well. Ray-tracing was a different story though. With the acquisition of ex-AMD employee Raja Koduri, they could be in a good position to become a major GPU threat.

This is nothing new. Ray Tracing has been around for a long time and talked about. As you mentioned Larrabee was a beast for Ray Tracing however at the time (circa 2008) AMD and nVidia were not so much. Its a very compute heavy way to do graphics.

They were supposed to move to a mix of both a while ago though. Back in 2011/2012 when DX11 was new they were showing it off again as the next big thing. However as said both AMD and nVidia still couldn't push 60FPS ray tracing.

There is a lot of talk of moving to Ray Tracing. There was a lot of talk then too. However unlike before where it is just a possible add-in to DirectX Microsoft has a API directly tied to it, DXR. nVidia has made RTX which is a hardware based tie to DXR. How it will work though, any DX12 GPU will support DXR, per Microsoft. However they will be doing it via Software. The Titan V and this new GPU from nVidia will support RTX which means it will be able to do DXR via Software and Hardware.

Guess we now wait to see AMDs answer to this. They are not particularly competitive in the GPU market and really needs to at least keep up with nVidia tech wise.

 

[bit_user]

Raterized graphics then rely on complex shaders to give the scene a sence of depth. With ray-traced graphics, the depth is an integral part of the scene and you don’t need a shader to bring it to life.

Raytracing can still utilize shaders of various sorts. The "classic" type of shader is a little program used to evaluate the color of an object, at a given point on its surface. While these would work a bit differently, for ray tracers, it's still legit to procedurally texture objects vs. using texture maps.

PBR is an alternative, but not one I foresee completely replacing procedural shaders.

https://en.wikipedia.org/wiki/Physically_based_rendering

 

[Giroro]

Throwing custom hardware and raw horsepower at Ray tracing is not a good solution, because it doesn't solve the fact that Ray Tracing is intrinsically too computationally expensive.
A game that uses ray tracing is always going to be limited to simpler scenes at a slower framerate than the current methods of 'faking it', which were designed from an efficiency-first perspective. It's like it doesn't matter how hard you push a heavy block to slide it across the ground, its never going to be as fast or as easy as rolling a cylinder.

We either need to find a far more efficient algorithm for computing rays, or work needs to start on inventing an entirely new method of realistically lighting 3D scenes.

 

[bit_user]

Throwing custom hardware and raw horsepower at Ray tracing is not a good solution, because it doesn't solve the fact that Ray Tracing is intrinsically too computationally expensive.
A game that uses ray tracing is always going to be limited to simpler scenes at a slower framerate than the current methods of 'faking it', which were designed from an efficiency-first perspective. It's like it doesn't matter how hard you push a heavy block to slide it across the ground, its never going to be as fast or as easy as rolling a cylinder.

One way to look at it is like fixed-point vs. floating-point arithmetic. For a long time, floating point was relegated to scientific computation. Eventually, it became cheap enough to put in mass-market CPUs and it's now used in lots of domains (audio processing, graphics, etc.) without a second thought.

But you're off the mark, on a few points. First, ray tracing scales with scene complexity better than rasterization. More importantly, it handles realism better than traditional rasterizer hacks. Things like reflection, refraction, depth-of-field, motion blur, area lighting, and global illumination are much better and more naturally handled by ray tracing. Taken together, what this means is that it's actually the easiest approach, when you're trying to achieve a high degree of complexity and realism.

 

[SiggeLund]

Even in raytracing you still use geometric figures with shaders on the outside.

 

[rantoc]

First ray-tracing i even did was using Real 3d on an Amiga 1000 computer, a single 320x200 frame took several hrs to render and a 640x400 could take almost a day -

Amazing to see all progress since the 80-90's

 

[10tacle]

If I remember correctly, the original Crysis was the first game to bring what ray tracing capabilities are to the consumer gaming world. I'll never forget my experience with it (not unlike with my first girlfriend 😍). Going from playing Half Life 2 in 2005 to Crysis in 2007 was like looking into a whole new world of gaming.

Of course, it also required a serious hardware upgrade which I did because I loved it so much. The debate on whether or not the actual game play of Crysis matched the eye candy is still out there however. And I've had all three series of it.

With that said, there is no shortage of games these days that bring even top end hardware to its knees at 4K like Dues Ex.

 

[stdragon]

I'm honestly surprised, and frankly amazed that rasterization has advanced to the degree it has! Rasterization is a complex visual "hack" in of itself, but a necessary to provide complex scenes at both resolutions and frame rates desired with current chip technology. By contrast, ray-tracing is algorithmically simple to program for (very simple compared with rastered these days), but takes a LOT of cycles to burn through the pipeline of calculations. Hence why we never had a good silicon solution to do RT in hardware.

At the end of the day, I think we will all look backward in time in the future and realize that rasterization in hardware was the exception, and not the rule. RT is the future for HW based acceleration, both now, and possible hundreds/thousands of years from now. It's just that superior of a method.

 

[bit_user]

First ray-tracing i even did was using Real 3d on an Amiga 1000 computer, a single 320x200 frame took several hrs to render and a 640x400 could take almost a day -

For me, it was PoV in DOS, using simple scene files I planned out on graph paper and wrote with a text editor.

I remember reading the FAQ and there was a question about whether there was any way to speed it up. The answer was they could probably get an order of magnitude by using a better scene graph/traversal. I was like "OMG, then do it".

 

[bit_user]

I'm honestly surprised, and frankly amazed that rasterization has advanced to the degree it has! Rasterization is a complex visual "hack" in of itself, but a necessary to provide complex scenes at both resolutions and frame rates desired with current chip technology. By contrast, ray-tracing is algorithmically simple to program for (very simple compared with rastered these days), but takes a LOT of cycles to burn through the pipeline of calculations.

The first time someone explained ray tracing to me, I couldn't believe it was something you could actually run on a PC. The amount of computation sounded so heavy, I figured you could only do it in a reasonable amount of time on a supercomputer.

So, with that expectation, I was actually surprised that my PC could raytrace frames in less than a day. IIRC, I was probably still using a 386, at that point in time.

 

[eDanny]

Amazing what my Amiga could do with its Denise graphics chip. The ray tracing was awesome to behold but extremely slow to process.

 

[bit_user]

Amazing what my Amiga could do with its Denise graphics chip. The ray tracing was awesome to behold but extremely slow to process.

Okay, but you know that the Denise chip had nothing to do with it, right? All of the ray tracing ran on CPUs, back then.

 

[Expgetible]

Back in the days, sitting by my Amiga 1000, I told a friend, I would not be impressed by 3D games until they started using real time raytracing. So, that day is soon coming. Great!

Also remember my rendering struggles in my Amiga days. A render I made took a full week on my Amiga 1000. Later I got me an Amiga 500 with a VXL-30 card and 40 Mhz 68030 with a 25 Mhz 68882 FPU and the same render went down to a few hours. And soon we'll get realtime. Sweet!
But actually, I'm rather impressed also with what graphic cards can do with rasters nowdays. Viva technical progress!