Another test with the ray traced AO kernel in Brigade. This kernel holds the middle between distributed ray tracing [Cook] and full path tracing [Kajiya] and provides soft shadows, refraction, reflection (glossy and perfectly specular), depth of field and ambient occlusion with adjustable ray length, all raytraced in real-time and without screen space limitations or other hacks.
The best thing about this kernel is that the image converges so insanely fast that I've decided to tone down the frame averaging (blur) almost to zero. The little noise that still remains is mostly visible around shadow edges and on reflecting surfaces, but it's almost negligible compared to the amount of noise when using the path tracing kernel. Brigade is now extremely close to real-time noise-free rendering and this is still without any fancy noise filters.
If the current rate of development continues, you might expect to see the Brigade engine at E3 next year (disclaimer: kidding)
Real-time rendered test at 800x480 resolution with 6 samples per pixel on 2x GTX 580:
UPDATE: According to this article, Unreal Engine 4 uses a form of GPU based real-time ray tracing for global illumination called voxel cone tracing in a sparse voxel octree (SVOGI). The technique was pioneered by Cyril Crassin and was presented at Siggraph last year (sparse voxel octrees were all the hype in 2008 thanks to Jon Olick's Siggraph demo, which was researched further independently by Cyril Crassin and Samuli Laine). The future of real-time ray tracing on the GPU looks bright with one of the largest game companies starting to use it on a large scale :)
UPDATE 2: A reader of this blog just sent me a screenshot of an awesome stress test with the public Brigade version: a giant cube containing 729k (90x90x90) tiny cubes, a total of 8.75 million triangles, consuming ~ 2 GB of video memory. Thanks Nicholas!