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This problem has been addressed many times before for copying UV's from one object to another object. But I need to copy UV map scale from one face group to another within the same object. In the example I've a brick texture that I've sized 15 times on X and Y. Now when I apply the same material to the chimney the texture is much smaller because the UV map is smaller. I can scale it by hand in the UV editor, but it will be difficult to hit the same scale factor and it just seems so random to do. Is it possible to just copy the UV scale from the walls? I know it's possible in 3DS Max..enter image description here

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2 Answers 2

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How we usually go about matching the uv is to scale all the uv which are suppose to have the same materials together after matching the scale with Ctrl+A (Match island scale operation.) If this is impossible in a particular workflow. Then try the following:

We usually end up using a checker map pattern to eyeball the sizes of the checker, to approximate the scale of every surface before applying the actual material.

  1. Create a color checker image go for 2048x2048
  2. Apply the checker to all the surface of the model.
  3. Enter Edit Mode and duplicate the faces in question and move it near the faces that has the scale you want to match. (Step for easier eyeball comparison)
  4. Select the duplicated face in the UV Editor and start scaling.
  5. Match the sizes in the checker pattern, and take note of the scaling factor on the bottom left hand of the uv scale before hitting LMB LMB.
  6. Delete the duplicated face.
  7. Enter the scale value from step 5. to the faces you want to affect.

If these answers are not satisfactory or understood, will be glad to post some images to help explain the workflow.

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  • $\begingroup$ It's my first model in Blender that I'm making after a Youtube tutorial and the author pointed out that it's important to mark seams all the time during the build up process. I did so but when it came to texturing it showed up in the UV editor, that my maps for the building are only partly okay. Only one wall had parallel map edges in the UV editor, the others were somehow bended and upside down etc. Thats why I did a project from view map on each wall individually and a cube projection on the chimney. This is how I ended up in this situation. What should I have done differently? $\endgroup$
    – Bart
    Jan 3, 2016 at 8:13
  • $\begingroup$ Use the method above when you can't get a fluid workflow to keep the scale of all the uv. Very often and in fact most of the time, complex models will end up with various method of unwrapping and have problems with scale. The truth is much later down the road it's a good thing, cause not all texture will appear right with one scale, hence the ability to scale them individually helps. As with seams and marking them. Try to learn how to unwrap simple objects and grasp it's concept. Just like all other things in life , the more you practise the better you get. $\endgroup$
    – hawkenfox
    Jan 3, 2016 at 9:31
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I hate eyeballing stuff.

My situation

I have attached a small face to an already textured object, applied the same material to the new face, ended up with completely misaligned UV-mappings:

enter image description here
enter image description here
The UV-editor:
enter image description here

In my situation modifying the UV-mapping of the original face (and the rest of the object) is not an option.

How-to

I can see that I need to rotate the UV-mapping of the new face by 90°. (In the very first image you can see how the texture of the new face is rotated by 90°.)
And I know the vertical scale can be matched by simply aligning the two vertical edges in the UV-editor.

Let's do that:
enter image description here
enter image description here

NOTE: Because the new face is touching the old one with its right side that's also the side its texture needs to be aligned to.
(By shifting the left edge of the UV-mapping in the UV-Editor along the horizontal axis you will be able to tell which edge is the texture aligned to. If it is not the Right one, rotate its mapping by 180°.)

The rest of the challenge is to "copy" the horizontal scale of the old face to the new one.

To achieve that you need to do following:

  1. Calculate the ratio of widths of both faces: use Measure on both of them -> new_face_width / old_face_width;
  2. apply the width-ratio to the width of the UV-mapping of the new face.

In my case the ratio ended up being 0.04761806754935521746299985989727

To apply the width-ratio you calculated:

  1. Align (only!) the width of the new face's UV-mapping with the width of old face's UV-mapping (use snapping "Snap to vertices" to maintain accuracy):
    enter image description here

  2. Apply the width-ratio to the new face's UV-mapping by scaling it along the horizontal axis: by first dragging the red axis of the scaling gizmo (doesn't matter by how much) and then copying the previously calculated number into the Resize dialog. You will end with something like this:
    enter image description here

Finalize

Now just move the new face's UV-mapping back to its place (use "Snapping to vertices" again):
enter image description here

The result

enter image description here

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