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I've some difficulties to find a satisfactory unwrap solution for this kind of long angled object with uneven segments:

enter image description here

I'm only interested in the brown faces which are delimited by two seams.

The solution must preserve the relative length of each straight segment, so that the texture containing a repeated pattern can be mapped evenly on the whole length (the sample is a ceramic baseboard).

Here is the result with a cube projection and a checker texture, other methods provide different results, but the distortion is always present:

enter image description here

I can't find a solution, except purely manual, to create the UV map while ensuring all segments:

  • Are oriented in the same direction on the map,
  • Have their length proportional to their actual size, to prevent texture distortion.

These constraints seem quite common, is there a standard approach?

Intuitively, I'm expecting the most simple method to lead to overlapping variable length rectangles, in the same direction, anchored at a corner (or a very large single rectangle).

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  • $\begingroup$ Do you have trouble unwrapping this at all or do you just search for a more convenient/automated solution than making a seam for each edge? $\endgroup$
    – bstnhnsl
    Sep 13, 2018 at 7:53
  • $\begingroup$ What do you mean with "purely manual". Is it setting the right seams? $\endgroup$
    – josh sanfelici
    Sep 13, 2018 at 7:54
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    $\begingroup$ @bstnhnsl (and josh): Marking the seams is ok, but whatever the unwrap method I tested, either segments are not scaled properly (leading to texture being deformed between segments) or are not oriented along the same U/V axis (leading to texture being at right angle). By "manually" I mean unwrapping using whatever method and then relocating each UV vertex at the appropriate location (and calculating the relative length of each baseboard segment). I'm a beginner, I may have missed something obvious. $\endgroup$
    – mins
    Sep 13, 2018 at 7:58
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    $\begingroup$ Could you upload your .blend to blend-exchange.giantcowfilms.com ? I'll have a look and give you some tips $\endgroup$
    – bstnhnsl
    Sep 13, 2018 at 9:19
  • $\begingroup$ @bstnhnsl: Thanks a lot, blend-exchange.giantcowfilms.com/b/5238 $\endgroup$
    – mins
    Sep 13, 2018 at 10:25

1 Answer 1

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First step:

See the different values under "Scale" on the right side? Your model is stretched in different directions.

enter image description here

for unwrapping to work correctly, apply the scale (the numbers for x,y and z should all be 1). select your object -> ctrl+a -> Apply Scale

enter image description here

Next

As you don't care about the blue backside, create a seam on the outside of the blue Part. alt+shift+rmb might help a lot in edge select mode (shift+tab).

enter image description here

If you unwrap now, the image will still be distorted. so we need to add one more little step:

We need to create seems in every corner. You don't need to go all the way to the bottom though – only as long as the tilted faces on the top go. This way your texture is continuous all the way through (you might or might not want that – if you don't, extend the seams to the bottom).

enter image description here

now select everything -> u -> unwrap

depending on the project i often get better results if I change the unwrapping method to "conformal" on the left panel.

enter image description here

The final UV in the Image Editor (The blue backsides on the bottom aren't 100% straight, but you don't care, right?):

enter image description here

And the Object in Material View:

enter image description here enter image description here

Let me know, if you have any questions.

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  • $\begingroup$ Woo! that's an impressive correcting with helpful explanations. Thanks, it answers exactly my question! $\endgroup$
    – mins
    Sep 13, 2018 at 11:28
  • $\begingroup$ How come the unwrapping isn't 100% straight as you mentioned? Is it because the mesh isn't straight, or is it just a Blender quirk? $\endgroup$
    – Decade Moon
    Sep 13, 2018 at 13:08
  • $\begingroup$ The unwrapping of the backside isn't clean. there are some seams missing for it to unwrap perfectly. The back, the bottom and the sides are still connected without seams. $\endgroup$
    – bstnhnsl
    Sep 13, 2018 at 13:23

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