Reply To: 4:37 – is it possible to delete the unused parts on the 2nd UV map?

[Dwayne Savage]

There is no blank UV map. If you don’t do anything, blender will do it. You can select the eyes in edit mode of the 3D viewport. Then in UV editor move them off to the side. Note: If they are attached to the rest of the mesh this is the same as selecting them in UV editor and pressing Y to separate them. If you want separate images to affect eye and body. Create 2 UV maps. One with eyes outside the bounding box area.(This is the UV you use for the body) The other will have the body outside of the bounding box area.(This is the one for the eyes.) If you want to do it all on one image then just move the islands around to make space for the eyes and move your eyes in that space. The UV editor works like 3D Viewport except it’s 2D. X left/right and Y up/down. You can use G, R, and S. 

Another option is to separate the eyes to another object and do the UV unwrap.

Thought process that works for me. The bounding area gets remapped to the image size. Thus the units of a UV Map are determined by the image. So on the x and y axis 0(Left side/bottom) to 1(Right side top) making 1 unit(Image). If you move your islands outside of the image you are just moving to the next unit(The image repeated). You can see this in UV Editor N-panel->View Tab->Check repeat image.(Only available if you have an image loaded in UV Editor) Also in image tab when you have a vertex selected you can see the coordinates using the 0-1. If you want to map to specific pixels then View tab->Check Pixel coordinates. This is default behavior of image node. When you add the image texture node you will see where it says repeat. If you click it you have the options extend and clip. Clip fills outside the image with nothing. If you use image alpha it will be alpha 0 outside. if you don’t it will be black. Extend takes the last row of pixels and repeats those colors.