Aug 19, 2010

Ambient Occlusion in PMV

Antibody 1igt with Ambient Occlusion from PMV by Jon Huntoon

From wikipedia: "Ambient occlusion is a shading method used in 3D computer graphics which helps add realism to local reflection models by taking into account attenuation of light due to occlusion. Ambient occlusion attempts to approximate the way light radiates in real life, especially off what are normally considered non-reflective surfaces.
Unlike local methods like Phong shading, ambient occlusion is a global method, meaning the illumination at each point is a function of other geometry in the scene. However, it is a very crude approximation to full global illumination. The soft appearance achieved by ambient occlusion alone is similar to the way an object appears on an overcast day."

To achieve this sophisticated look is mostly unattainable in other viewing software. But PMV makes it painless. Here's how:

1. Open Deja Vu
2. Select Ambient Occlusion
3. Select the geometries you'd like to have ambient occlusion applied to and then click 'Add'.
4. Select cavity darkness and overall brightness (I left these settings default).
5. Click Compute.

That's all. Sit back and watch the computations chug away. My rendering took about 2 minutes on a new iMac. The other cool thing about this is that once the shadows are calculated, they remain. You don't need to recalculate every time the camera moves like you would in other 3D viewers. Have fun!

Here's what a secondary structure looks like with ambient occlusion turned on.
Ambient occlusion on secondary structure.
Note: the stick-and-balls didn't get rendered.

BONUS: In Deja Vu, select 'Scene Antialiasing' and increase the value to at least 8 for cleaner edges.

-Jon Huntoon


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