Distorted UV Mapping

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Gustav
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Joined: Tue Jul 30, 2013 1:07 am

Distorted UV Mapping

Post by Gustav » Tue Jul 30, 2013 11:50 am

I have a Problem with distorted textures in Blender 2.68 (renderer is cycles). I have created a simple test cube with applied scale and rotation. The uv of this cube looks like this: http://kroetentunnel.chickenkiller.com/test3.blend.jpg

This texture is distorted along the face normal http://kroetentunnel.chickenkiller.com/test2.blend.jpg)

There is less distortion with a subsurf or multires modifier (the distortion is still there but unrecognizable): http://kroetentunnel.chickenkiller.com/test1.blend.jpg

Does anyone have this problem or is it a general problem in blender?

LaazRockit
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Joined: Mon Aug 26, 2013 7:51 pm

Post by LaazRockit » Mon Aug 26, 2013 8:27 pm

Similar Problem. (Blender 2.66a) Made an oval uv-sphere and unwrapped it. After appying the material it looks like this:

http://www.picturehost.eu/uploads/623f2 ... eError.PNG

Any idea how to fix it ?

brasshat
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Joined: Mon Nov 16, 2009 1:06 pm

Post by brasshat » Mon Aug 26, 2013 11:13 pm

G & Lr, in both cases it looks to me like the solution is to add geometry, especially in the direction perpendicular to the distortion.

ns

MarcClintDion
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Joined: Wed Dec 12, 2012 8:20 am

Post by MarcClintDion » Tue Aug 27, 2013 1:43 pm

In many cases, if you triangulate the model this distortion will either look the same or it will be corrected. If it looks the same, then flip the new edge so that it runs from the opposite two corners. Consider making this change temporary to start off with since many tools require quads to function properly. You might want to make a note of these areas and apply the correction towards the end when the model is finished. If you want to stick with quads then you can apply the 'Triangulate' modifier and use the 'Beauty Subdivide' check-box to flip the edge. Now you can turn it on and off as needed.

From what I understand, video cards only deal with triangles at their most basic level. Blender has to guess at which direction the quad should be split, if Blender does not do this then the GPU will have to... unless you do it.

A long time ago when Google sketch-up was still fairly new, I watched a video on how to make models for Google Earth. They have a tool that will distort the texture to match a square shape. If you do something like this in GIMP or Photoshop and then apply this corrected image to perfectly square or rectangle shaped UV coordinates then you might by-pass all of the above since Blender will no longer have to interpolate how the image should be distorted at all the various points between vertices.

MarcClintDion
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Joined: Wed Dec 12, 2012 8:20 am

Post by MarcClintDion » Tue Aug 27, 2013 2:07 pm


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