Is real time ray tracing feasible?

Accelerated Computing CUDA CUDA Programming and Performance
1

hi everyone:
i’m wondering if real time ray tracing is possible on comsumer’s hardware ( 5870 or GTX 260 )
i’ve read some paper work which present some real time ray tracing for complex scenes consisting of traingles. ( “real time kd-tree construction on graphics hardware” , for example )
But i haven’t downloaded any ray tracing demo that is real-time from internet.
i mean the one for normal scene used in raster method.

Use whatever u want, cuda , openCL or even AMD CAL , does any one percive real time performance?
Actually i’ve finished the algorithm of kd-tree construction and ray tracing on GPU using OpenCL and Brook+ seperately, but the performance of them is still far from real time.

Is there something they don’t mention in their work? (Such as use rasterization for primiray intersection test.)

Any idea is really appreciated!!

2

Soneone here posted a Windows .EXE that showed some realtime animated spheres reflecting a checkerboard on the ground. I’d call that real time.

When you go to complex scenes and geometry, you’ll have a hard time hitting realtime, unless you go for multiple video cards operating in parallel.

Check out the nVidia Optix raytracing engine. It’s available now.

Christian

3

The Optix racy tracing engine was shown to do it at 30 FPS… What is the definition of real-time?

4

Any youtube video of that? How complex was the scene?

5

i consider a 24 FPS demo real-time one.

i’ve checked the Windows.exe demo on my gear, it’s real-time , but it’s too simple. There is no kd-tree construction each frame and no triangle ray intersection test. So the demo is only for show not for general purpose.

For a more general one , some researchers present real-time ray tracing in their paper? But they don’t release demo. And a lot of them have perceived real-time performance on consumer’s hardware.

For example, in “real-time kd-tree construction on graphics hardware” from Kun Zhou , Microsoft Research Asia, they reached 32.0fps rendering the toy scenes , the resolution of the image is 1024*1024. And their work runs on GeForce 8800 ULTRA which is not very powerful in current generation hardware. It’s incrediable. But how? how do they do that?

6

Toy scene is small ;)
Anyway I consider current raytracers more like “interactive speeds” rather than “real time speeds”. They are still a little bit too slow for pleasent video (~30fps) or games (where you need about 60fps), but of course if you choose a simple enough scene and strip out some more advance lighting features you will reach that framerate. But if you simplify too much you are nowhere better than with rasterisation in terms of quality and realism.
However reaserch is going forward as well as GPUs are getting faster and more powerful. Therefore I believe there will be some high quality and fast raytracers soon (in a year or two).

7

Let’s take a look at the two demos: the one in the paper and the first demo in this page http://developer.nvidia.com/object/optix-examples.htm .

Difference:

  1. things in the former one consists triangles while there are only spheres and plane in the latter one.

  2. The resolution of image is 10241024 in the former one while it’s 1024768 in the second one.

  3. They reach almost 30 fps by a GT 8800 ULTRA display card. While i only percieved 50 fps by my GTX 260 card.

  4. There are 11k primitives in the toy scenes. There are only six primitive in the scene of the second one.

8

Thanks for pointing me to these. It is possible to patch these .EXEs so they run on consumer type graphics cards - I am not going to link to sources of such hackery.

Let me just say I am impressed - even on my lousy GT220 some of these demos are nearly interactive. Especially the 3D Julia set demo could be interesting. It can be turned into a Mandelbulb pretty easily, I hope.

Christian

9

I want real time with 100k-500k triangle scenes :)

That is why I said “Toy scene is small”

10

260K triangles, 1680x1050, 40-50fps on GTX260 216 cores overclocked by ~10%, still work in progress so it will probably look better and be faster:)
and no exe, just screenshots, maybe some day I will post an exe.

and I already know that it has bad image quality;)

[url=“http://kolos.math.uni.lodz.pl/~pawel/RT/hires1.jpg”]http://kolos.math.uni.lodz.pl/~pawel/RT/hires1.jpg[/url]

[url=“http://kolos.math.uni.lodz.pl/~pawel/RT/hires2.jpg”]http://kolos.math.uni.lodz.pl/~pawel/RT/hires2.jpg[/url]

[url=“http://kolos.math.uni.lodz.pl/~pawel/RT/hires3.jpg”]http://kolos.math.uni.lodz.pl/~pawel/RT/hires3.jpg[/url]

[url=“http://kolos.math.uni.lodz.pl/~pawel/RT/hires4.jpg”]http://kolos.math.uni.lodz.pl/~pawel/RT/hires4.jpg[/url]

I think that real time ray tracing with some tricks could be used in games today, but cost is really high compared to results, it will change probably in a year or two;)

11

Nice. But what I see these images consists only from direct illuminaction + reflection or is there something more into it?
Nevertheless: really nice. Good, complex reflections is not that easy with rasterisation.

12

there is no indirect illumination, full per pixel GI would result in less than 0.2 fps - faaaar from real time;)

I plan to implement some tricked indirect illumination, maybe in next year;) Before that I must rewrite some parts of raytracer to improove performance and add gpu tree construction to support animated objects;)