Why dont we use Ambient Occlusion maps?

Hey there,

I just finished the sculpting a dragon - texture baking lecture in which we baked both a normal and a cavity map. Now that reminded me to take a look at what we did in other GDTV courses, for example the Blender Character Creator v2.0 for Video Games Design course. So this is my 7th GDTV Course I think (some of them unreal, most of them blender courses) and I think we never really used ambient occlusion textures, did we? I actually did not even know they were a thing until I downloaded some PBR Textures and brought them in.

Does anybody know why we dont use ambient occlusion textures here and also does anybody know the difference between a cavity map and an ambient occlusion texture? For the latter question I saw this thread discussing the difference between ao and cavity maps, but Im not really sure what to make of it.

As always thanks in advance for your help!

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From the web:

"Cavity and Ambient Occlusion maps are specialty textures that can be generated in ZBrush using the masking tools. Cavity maps are essentially the blue channel of a normal map and represent dark shading in the crevices of the model. They can be useful as a multiply layer over a diffuse color map to accentuate details or as a diffuse map in Maya to help punch up the high-frequency details in a render. Figure 9.67 shows a cavity map. It is essentially a black-and-white map in which black represents the recesses and white is the high points.

Cavity mapping is intended to help mimic Ambient Occlusion, but it is not by nature an Ambient Occlusion effect. It also has several other uses. Ambient Occlusion works by casting rays out from the surface of a 3D model. If a ray hits another surface before dying out, then a grayscale value is recorded that represents how far that ray traveled before being occluded. This is how Ambient Occlusion maps generate darker shadows in tight recesses like inside ears or under the brow ridge."


Thanks for the reply! Its interesting that you bring that quote up, because lower in the thread I linked there is this comment:

Which links to another thread about cavity vs ao maps. Now i dont know if the user “bandages” is actually right or wrong here, just pointing it out.

I did however find this polycount docs pretty helpful saying:

A cavity map is a texture that stores small-scale ambient occlusion. Also called a Crevice map.

I think I got it now due to that first sentence and looking at the initial ao / cavity map thread above where the user 0451 commented with the example showing the differences.

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