GPU based Raytracing with Pixel Bender and After Effects
27. September 2009 – 12:29Tags: After Effects, Ambient Occlusion, AO, GPU, Pixel Bender, Raytracing, rendering
Since some years the idea of harnessing the power of modern graphic cards for 2D/3D applications has become more and more popular.
Today we find GPU support in many CG applications like Photoshop or After Effects.
But first the fun part: Watch a video raytraced with PB and AFX!
The chaos group is even working on a GPU based real time version of Vray – a widely used modern GI raytracer.
In fact GPU shading is often more performant plus it quasi ‘adds’ an unused/inactive processor.
One could argue that Pixel Bender doesn´t quite fit the term as its mostly run in software mode (on the CPU) – for
example when executing a PB shader in Flash or rendering it with AFX… for now.
But PB is still young and the prospect of being able to run it within multiple adobe platforms (Flash,PS,AFX) is very compelling.
When I saw Tom Beddard´s PB port of Keenan Crane’s genius julia set tracer, I remembered that I had planned to get into PB GPU raytracing once I got around Mike Welsh´s PB raytracer.
So I spend some time with it, created a scene similar to ‘The Eye’ and added viewport controls as well as anti aliasing.
The result can be viewed here.
Rendertime was 3:10 on a Q6600 for 4700 frames.
And here is the modified shader.
I also fiddled around with adding an inside-out AO (ambient occlusion) pass but wasn´t able to get satisfying results.
It even almost fried my GPU in the process so in conclusion it’s doable but sadly not practical.

