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blacksmith3D
11-09-2005, 05:35 PM
Here is a question regarding LW models and multiple UV maps...

Many file formats do not support multiple UV mapping sets (OBJ for example). Now Lightwave allows you have multiple UV maps for a single object, which can be assigned separately on each surface channel. For example, if you have two surfaces "Skin" and "Clothes", then you might have

Case A:
Surface Skin

Color Map


UVMap = MyFirstUVMap
Surface Cloths

Color Map


UVMap = MySecondUVMap

This is pretty easy to deal with when converting to another format. Now, there may be the case where single Surface may refer to multiple UV maps. For example....

Case B:
Surface Skin

Color Map


UVMap = MyFirstUVMap

Bump Map


UVMap = MySecondUVMap

This case would be very problematic when converting to a format that only uses a single UV map. With that being said, would it be at all common for someone to use Case B, where a single surface refers to two different UV maps?

If the answer is no, then I can simply instruct the plug-in (that I am developing) to warn the user that this case is not supported. If this is a common practice, then I have to develop a more sophisticated way of dealing with it.

You opinions would be greatly appreciated :)
Dave

mkiii
11-10-2005, 01:35 AM
I'd say case A is definately the most likely. In that case, combining the 2 UV maps into one would have no affect on the outcome other than having to change the name of the map that is being referenced to one name instead of 2. I often do this manually when I combine parts from other models. It doesn't matter if the UVs overlap as long as the surface that uses them is using a different bitmap.

Case 2 is not something I would tend to use personally, since it is usually more intuitive for me to create your bump maps when you have a colour image to reference or paint over, or for that matter, simply convert to a greyscale. I do both hi res stuff & game characters btw.

However, I can see that it may be the case that a bump map might use a comletely different set of UV data if it has been created in another app such as ZBrush etc. A spec map, reflection map & so on may also need this approach. In particular. Normal mapping techniques may need to use this method, as in most cases, they produse an unwrapped uv map that might not be suitable for use in creating the colour map. IE too fragmented.