Attempting to understand "UV Channels"

[Anonymous]

For context, please see this thread:

   Is there any way to display the underlying UV map in 3ds Max? 

This 3D model is advertised as not having overlapping UVs:

Cartoon Boy at CG Trader 

Using UV Mapper or another application I can see many overlapping polygons.

However, if I select the boy's parts one at a time, there are no overlapping polygons:

Below, I selected "clothes" (2 sections) and there is some degree of overlap:

My doubt is this: could this be what is known as "UV Channels?" The individual UVs would not have any overlap?

TIA

[10DSpace · Accepted solution]

It is hard to tell exactly from what you posted, but most likely there are multiple material ID's and the different materials are applied to specific material IDs.   But all of these materials are in the same U1V1 space, so if all material IDs are selected then all of the materials are shown on top of each other in the Unwrap UVW editor.  However, if only 1 material is selected, then it alone is shown and the UV islands specific to that material id have no overlap.   See screenshots of a simple object to demonstrate.  Have you tried rendering the object?  It may still render fine and present no problems for you.   

[Anonymous · Accepted solution]

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@10DSpace wrote:

Have you tried rendering the object?  It may still render fine and present no problems for you.  

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Actually, I am using that model of a boy as an excuse to learn more about the subject.

It was the first model in which I noticed that "inconsistency".

It renders fine.

Thanks!

-Ramon