Multiple UV sets in 3ds Max
I'm working on an environment at the moment which has overlayed uv's utilising the same tileable textures. I've seperated the environment pieces according to which tileable texture they'll be using and unwrapped accordingly. I'd like to bake an ambient occlusion map from the all of the geometry on one sheet and overlay if possible. Is it possible to use multiple uv's sets for this type of thing and how can this be set up?
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This defaults to "1" (ie. the first set of UV coordinates) ... if you set it to "2" or higher, it will store the original UVWs in Channel 1, and you can do a new unwrap in Channel 2.
Then you can set up the material in the Material Editor to use Channel 2 for your ambient occlusion texture.
For each unique channel I like to apply a new Unwrap UVW modifier on top of the stack. It makes editing each channel easier since you can toggle them on/off and sometimes when you switch the spinner to a different channel it resets your UV's to the last baked layout. Kind of annoying.
I think you can hit reset UV's after changing the channel and it will restore the current layout, but I rather not deal with that crap.
Sorry for the bump.
There are a couple of ways you can work.
1. This method is easier to understand. Leave your first Unwrap modifier there on channel 1, and add a second Unwrap modifier set it to the correct channel and ignore the warning. If you need to modify channel 1, just click on that modifier and edit.
2. This method keeps the stack clear, but can be confusing at first. With your channel 1 UVs complete, collapse the stack. Add an Unwrap Modifier change the channel and ignore the warning. Collapse when you are done. Here's the confusing part. If you need to edit either channel, you'll apply another Unwrap mod and change the channel. The UVs may look might be wrong, but all you need to do is hit the Reset UVWs button. The Reset UVWs button will query the mesh for the last collapse UVs for the current channel. But don't edit a channel, and then change the channel. Then you will lose work. Always collapse and add a new modifier.