Seamless Blender Baking

I was trying out the tips for baking in Blender from this thread:

http://forums.secondlife.com/showthread.php?t=198690

I would like to bake textures that will be seamless at the waist and neck. I assume this means I should join the whole body, and then remove doubles. But then how do I get it to bake to 3 different textures (head, upper, lower)?

I'm not a Blender user, but generally there are usually a couple of different ways to accomplish that. You can see if Blender will allow you to bake only selected polygons, then just select the polys that correspond to a particular template. Blender may also allow baking by material, in which case you can use three different materials (that are actually the same). The last and most complex way is to edit the UVs on your avatar model so that the three templates are stacked vertically or horizontally. That's who I do it in Max. I redid the UVs as a vertical stack. Max sill only render a square image when baking so I render 2048x2048 and resize to 512x1536 and split it into three 512x512s.

That last method Chip mentioned was what I was thinking I'd have to do, though I don't know how to do it. I should probably mention that I'm new to Blender, and step-by-step instructions for how to do things in Blender would be great if someone can do that.

Also, if I join all the body parts, how can I still quickly select just the torso vertices, or just the head, etc?

I know there are some Blender gurus around here...

I don't use blender either, but I have also done what Chip does with the UV's. In my case I have separate models for the head, torso, and lower body that use a standard UV for each area, and I also have a full body model with all UV areas spaced out on a 4096x4096 grid (which supports 2048x2048 for each body area). I used Ultimate Unwrap 3D to make the modifications for the full body model.

I'm currently using a SVN version of Blender and the UV Face Select mode has been removed (it now works from faces selected in edit mode) so it's hard to do a step by step that is correct for the release version.

Basically you can create multiple images in the UV Image Editor window and assign different faces to the different images. When you bake the object, all images with faces from that object will be updated.

I also create a low res dummy image for one arm, You just assign the faces on the left arm to the dummy texture to avoid strange things happening where the two arm UV maps cover each other.

You could also fix this in the texture by a pure black layer to act as a base for the the material mix, but as the low res dummy texture approach cuts down on baking time I find it an easier solution.

If you are having problems at a particular point I can probably suggest something, it's a lot easier to help with specifics than try to give a complete overview of what to do.