I'm trying to unwrap my first model and there's some problems I can't get around. First, my circular faces are getting an oval shape in the map (image below), second, sometimes a mesh will get much bigger in the map than it is in the model and I don't know how to make the canvas map larger for it to fit in. Thirs, some of my faces are turned into edges in the uv map. Can anyone shed some light in what I could do to solve this? Thanks in advance.
Your object might have non uniform scale
Unwrapping unmodified circle works as expected
However, if we scale it by 2 on x-axis, and then reverse the scale in edit mode, the unwrap is squished even though the object looks identical to the first one.
The previous action sets the object scale to 2,1,1. While calculating the UVs, Blender sees that the object was scaled by 2 in X direction, so it must account for that and not give extra texture space in X direction. Hence the UVs get squished.
[blender: The object looks like a circle but it is scaled by 2 on X. So originally it must look like in ellipse. I'll perform the operations on ellipse,since that's the original geometry]
You also get a reminder in the status bar.
You can fix this by applying the scale. press Ctrl A and choose scale. Goto edit mode and unwrap. This will set the scale to 1,1,1 => tell blender to set the original geometry to what it looks like right now