12 septiembre 2015

Removing ambient occlusion from photo-scanned subjects

This is a simple idea I came up  last night. I was making a little stone that would be used rotated in every axis. Then I figured out that the ambient lighting of the original capture won't match with the scene. This was the subject:

So the idea was to convert this diffuse into an albedo. The method consist on emulating the scenario to get a simulation of the original lighting conditions I had there. Then I will use the inverse of that result to brighten the original captured diffuse.
You see there the lighting came from every direction from the clouds and a little percent of it came from the ground (typical hemisphere lighting).
So the scene can be emulated like this:

Here is the resulting ambient occlusion:

Captured albedo. Notice it matches perfectly with the emulated AO


Now, I inverted the AO and blended it as "Linear Light" with opacity 50%. Other blending modes may be tested; "Lighten" seems to work pretty nicely too.

I can now bake a new AO without any other geometry than the model:

And finally, the diffuse texture after the surgery session:

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