It's not really Ambient Occlusion though
Your tutorial is great, very handy and clear starting point for making Occlusion.
But... what you're finally showing is not really Ambient Occlusion.
Ambient Occlusion should only really affect the Ambient part of your shading model :
A simple version of a shading model : Ambient + Diffuse + Spec = Beauty
I noticed that you're multiplying your beauty by your Occlusion results, meaning you're not actually making Ambient Occlusion in the end.
Ambient Occlusion should fit into the simple shading model above like this :
(Ambient_Occlusion * Ambient) + Diffuse + Spec = Beauty
Your tutorial has more in common with the ideas of 'Contact Occlusion', an odd (imho) artistic rendering of shadows. eg we'd still get occlusion even if a bright light aimed directly into the nooks and crannies, which cannot be correct.
Ambient Occlusion's not really a shadow, so much as 'an-absence-of-ambient-light'. It looks good when you use a longitude/latitude environment map for your ambient light.
Ambient Occlusion is a, highly and easily tweakable, artistic nod towards 1 of the visual features of Global Illumination (or radiosity rendering).
Sorry to nit-pick, but nomenclature's important.
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