September 6 2009

Screen-space color bouncing

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While work­ing on my Occlu­sion­ist plug-​​in I stum­bled across an inter­est­ing side-​​effect of gen­er­at­ing ambi­ent occlu­sion in screen-​​space: It’s pos­si­ble to achieve com­pu­ta­tion­ally expen­sive global illu­mi­na­tion effects such as color bounc­ing in the same way!

And what’s best… it comes pretty much for free!

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Screen-​​space color bounc­ing (right)

As it turns out, when pro­cess­ing ambi­ent occlu­sion the Occlu­sion­ist is already doing every­thing required to achieve color-​​bouncing, so it’s sim­ple enough to call the source image’s color and bounce that around to sim­u­late a nice final gather or global illu­mi­na­tion effect right in After Effects.

The over­head is some­where around 10 – 20%, which is totally accept­able when you con­sider that true 3D global illu­mi­na­tion effects gen­er­ally take much, much longer to render.

Hav­ing access to screen-​​space ambi­ent occlu­sion plus color bounc­ing right within After Effects will cer­tainly make for some very inter­est­ing effects and opens a whole new world of possibilities!