Collada Mesh Export with Multiple Textures

[micheus]

but after I make it external, I notice in my Geometry view that that face group's faces are invisible (see first attachment) ...

I think that is the 2nd attachment.
Yeah, in order to avoid that, in the options for Create Texture include Draw Faces option. It will use the face object color to draw.
I never knew if that should be the right behaviour.

is that when I follow the steps for the second face group, it puts the second face group in the first's texture file and UV map (see second attachment) ...

When creating the new UV for an other group, before you start, you cannot forget to rename the last UVmapped material and its respective image. I also recommend you to close the AutoUV window after you create every texture.

When you are editing the UV maps in the AutoUV you will always see all the meshes overlapped because wings will pick all UV mapping information for the object and process it.
What I do recommend for that situation: use the context menu in the Outline window to Select the UV mapped material you want to edit, then open the AutoUV window (main menu Window->UV Editor Window). The window will be displayed with all UV maps overlapped, but with the desired one selected. Then, you use the menu Select->Hide Unselected Objects to leave only the mesh you want to work.

You probably will need to use the edit tips to fix your current problem with two groups using the same material.

It seems to be complicated, but after you get the way it isn't.

Let us know if you need more help.
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obs: we have only 300kb for attachment, so I recommend you to use any other cloud storage to share the images. In the editor bar there is a button for Photobucket. In case you don't have another option maybe you could try to join them.