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sakura_chan

Best use of ambient occlusion map?

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I'm wondering about how most people use their AO map. I tried putting it in the obvious place (ambient shadow channel) but the effect is so weak and really only appears at a distance. I tried merging it into my color maps but it looses a lot of the effect and caused some discoloration. I then tried it in the detail channel which looked best, but I was already using that channel for a tiled dirty metal detail texture. I noticed that some modders blend it in subtly to their color maps, add it to their AO channel AND their detail channel. Is this the best way to do it? Is there any way to add my dirty metal texture?

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I tried merging it into my color maps but it looses a lot of the effect and caused some discoloration.

which program are you using to make your textures? it sounds like you merged/blended the AO map into the colour map by just reducing its opacity. the problem is that the white parts will wash out the colours. in photoshop there's a little roll down menu (in the layers window) next to the opacity slider which is set to normal by default. set that to multiply to only apply the dark parts of the AO map onto the colour map. it's like automatic masking. you could also create a mask for the AO layer using an inverted version of it. meaning that in the mask (alpha channel) the parts that are black in the AO should be white and the other way around.

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In general, when blending shadow type maps with another map you should use the multiply blending method, and if you're adding light maps, you should use the add blending method.

The macro map multiplies with the diffuse map, so I think it would do the same thing as just blending it in photoshop. The _as map blocks out the ambient lighting, not direct lighting, so the effect is only visible on the dark side of the object.

I blend ao with my diffuse map and use an _as map.

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A tiny humble question: ambient shadow map can be made with Pal2pac? thanks

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Good info! I messed around with it some more and I found that it worked really well as a detail map. I used the AO map as a base, then I added the panel lines (it is an airplane) and the tiled metal texture both using multiply. This left the color map free of any panels or shading. I used the AO channel to simply set the ambient shadow strength to enhance the partially chrome look of it.

If I did have to use it in the color map I would go with the multiply blending. The problem was with me using the wrong blending mode, trying to adjust it with opacity and having it wash everything out because AO maps are [128,128,128] grey as default

@Robster no an ambient shadow map is usually rendered in a 3d modelling program once it has been fully unwrapped. Blender is what I used because it is free (and legal)

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Well, you can get student licenses for autodesk products if you are 'unemployed'. I use quotes because that's the option you can select to get a student license.

I think the detail maps are combined with the diffuse texture using some kind of overlay algorythm where it's brightened if it's above grey and darkened if it's below grey. IIRC _dt maps are used to get sub pixel detail out of your diffuse map. You can tile it using your uv transforms in the shader. So if you have a 1024x1024 map and you want to get some micro scratches in the material, you can use a tiling detail map. I haven't really had any really great luck with it, though, as the pattern seems quite obvious. Another use for them is in damage rmats. You can use a similar rvmat to your normal glass texture, say, and then use the detail map to define cracks and holes. This, I've found works really well.

The benefit of just blending the ao map with the diffuse map and not using another map in the shader is that it reduces the amount of video memory required to render the object.

@Robster

It depends on what you mean by make. Pal2PacE can make the appropriate paa type, but it can't produce the artwork. _as maps are ambient occlusion maps when applied to occlude the ambient lighting (the ambient light + environment map) in this case. To produce the map you'd want to use a 3d program with a ray tracer to produce an ambient occlusion map, and maybe combine that with a cavity map (which is a sort of ambient occlusion map rendered by using the information in a normal map).

Edited by Max Power

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Good info! I messed around with it some more and I found that it worked really well as a detail map. I used the AO map as a base, then I added the panel lines (it is an airplane) and the tiled metal texture both using multiply. This left the color map free of any panels or shading. I used the AO channel to simply set the ambient shadow strength to enhance the partially chrome look of it.

If I did have to use it in the color map I would go with the multiply blending. The problem was with me using the wrong blending mode, trying to adjust it with opacity and having it wash everything out because AO maps are [128,128,128] grey as default

AO/AS maps should not be 128.128.128. The background color for AO maps is white[255.255.255], with darker areas only in the occluded parts. Might have misunderstood you here though.

@Robster no an ambient shadow map is usually rendered in a 3d modelling program once it has been fully unwrapped. Blender is what I used because it is free (and legal)

In addition to what max said: for ALL non-commercial projects, Autodesk grants you a free 3 year license for all their products. I have read the EULA (it used to be a different system when i was using the students version back in uni, one where you had to provide detail information about the university and it's field to be qualified for this sort of license) and you are free to use their products for arma modding, legally. - not that there is anything wrong with blender btw.

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AO/AS maps should not be 128.128.128. The background color for AO maps is white[255.255.255], with darker areas only in the occluded parts. Might have misunderstood you here though.

oops I meant the one I was making was 128 instead of 255. You can change it in blender by changing the diffuse color. My new AO maps have a white base and I did decide to merge it into the diffuse using multiply.

Edited by Sakura_Chan

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