UV unwrap : aspect ratio?

Question Materials and Textures

Please pardon if this is a silly question.

I want to select a square face and UV unwrap it onto an image (which has something square in it). I hoped to be able to move/scale in the UV editor to make them align.

My simple problem is that I can't seem to unwrap a square face as a square. "UV : unwrap" and "UV : project from view" (orthogonal) both seem to adjust the aspect ratio to match the overall image (which happens not to be square).

If I display properties and edit UV coordinates of each mapped vertex to have values representing a square, what is visible on screen is a rectangle.

Of course I can "roughly scale" in the editor to get something close to a square. In my case, precision is important. The image has rulers with measurements and I want to use them to place the vertices of my mesh.

I must be missing something.

  • Omar Domenech replied
    It is very possible that the scale of your object is not 1, 1, 1 and Blender is UV Unwrapping accordingly. So select your object, Control + A and apply the scale then unwrap. Try that first and let us know.
  • Martin Bergwerf replied

    Hey techworker1 ,

    I am no expert in UV's, but this sounds like something that should be easy (or at least possible) to do, but I have no idea as to how to achieve this in Blender....

    I am intrigued though...when I find  a way, I will let you know immediately!

    There are probably workarounds, with several Meshes and different UV Maps...but a straightforward way???

  • techworker1 replied

    Blender seems to initially assume U=0.0-1.0, V=0.0-1.0 regardless of the image shape.

    If I open Properties in the UV Editor, and mess with the aspect ratio values, the image texture can be distorted to a square, and then the unwrapped "square" vertices also appear as a square - not what I want.

    Probably not worth all the trouble. Workaround is to only unwrap on a square image (make an edited image copy if needed).

    It would be convenient sometimes to have a "project from view, preserve shape" option. Maybe it exists and I haven't found it. Maybe my use cases are unusual (but I've run into them from time to time).

  • Martin Bergwerf replied

    "It would be convenient sometimes to have a "project from view, preserve shape" option"

    Yes, indeed...maybe something for the Right Click Select Forum?

    As I understand it, Daniel Bystedt is currently working on the UV Editor...amongst his other jobs of course..

  • Omar Domenech replied

    I think you may find an answer in this lesson from JL's course. I remember him talking about a Blender quirk doing that stretching thing. I'd be interested to know if your solution is in there and what was that all about. So, report back your findings!


  • techworker1 replied

    I did take that course recently (a very good one). The lesson is, indeed, about how Blender stretches/reshapes things when it unwraps, but it basically assumes that everything is stretchy. Typically what you want is to get lots of faces to fit / pack  / cover a surface without distorting too much. Blender uses various rules to try to help you. "Preserve shape" seems to be irrelevant for most texturing - just my special cases I guess.

  • Shawn Blanch replied

    Hey Kevin, without seeing maybe this workflow would help. Use project from view, set the cursor to the middle of the UV space and then snap to cursor and you should be able to scale almost perfectly.

  • Omar Domenech replied
    I'm curious about this one. It'll be great if we can troubleshoot this one over on Discord. Maybe jump into a live channel and try stuff out.