Baking Shadows

Elodin

Hi, I need to bake shadows into the diffuse texture and I seem to understand how the process is done. What I don't get is what to do when you have one texture for the whole asset and there's many uv islands in one space, overlapping each other.

How do I proceed then?

Because all the tutorials I found were insisting on having each UV island separately.

Ashaman73

If you want to bake a shadow into your diffuse texture, the whole mesh surface gets unique, therefor you can't reuse the same texture space for different surfaces.

Sometimes you can use some fake, ambient shadowing which will not be so obviously, but if you want to bake real shadows you need to separate your uv islands.

Elodin

How do I do this fake, ambient shadowing?

Any tutorials i could use?

Eric Chadwick

You need to make a second UV set (UV2), with no overlapping or mirrored UVs (you can cheat this some, but it's difficult, depends on your lighting). Then you bake the diffuse map (using UV1), along with the lighting, into UV2.

What software are you using?

Eric Chadwick

Some info here that might help
http://wiki.polycount.com/wiki/Light_map

Elodin

I am using maya. Basically I need one texture in the end of the process =(

Elodin

What if I have a single piece of wall, which is duplicated all over the place, I could use the same texture space right? In any case, I have terrible problems with v-ray right now, it just makes everything black...

Eric Chadwick

No you can't, if you're baking the lighting&shadows into your diffuse. Each wall has to be its own UV space.

Elodin

Ok, so what do I do if the client wants a model with lot's of mirroring walls and shadow baked on top, how do I do that?

Eric Chadwick

make 1st UV for the diffuse etc. maps (overlap and mirror as much as you like), 2nd UV for the baked shadows (every polygon gets its own space in the UV). Bake shadows to UV2.
http://www.3dtutorialzone.com/tutorial?id=48

Elodin

Ok, I managed to create a baked diffuse shadowmap, but now model doesn't look very nice.

I take it is possible to transfer those changes.

Eric Chadwick

You need a shader that multiplies the UV1 textures with the UV2 texture. I put some images on that lightmap page, might help you.

Not sure how to get this working in Maya, you probably need a specific shader, maybe one of these? http://wiki.polycount.com/wiki/Shaders#Maya_Shaders

Elodin

Thank you so much for the help, I'll see what I can come up with.