I have a texture image that I wanted to place on the outside of an object (boolean intersection between spherical shell and angular wedge). Unfortunately, when I do this, I get blurring only in the horizontal direction and nothing in the vertical direction. It is possible this could be from a UV mapping issue. I am very new to this and thought that I had UV kind of figured out but I could be wrong. Here is an image of the poor result:

Example of bad blur

I have tried to use the information contained in the following post:


The following are my shader setups for the ring:

Full Shader

Full Shader View

Just Image Blur Node

Just the Image Blur Node

As an aside, for some reason, the image blurring fails to work at all when I pack the image. Any help on that would be great as well. Below are the blend file and the necessary image.

Texture Image


After I used the pack all to blend file from the 'File' menu, I think the images got correctly packed so that the blurring still works, but it is still incorrect. The updated blend file is below:


1 Answer 1


The problem is mostly a result of aspect ratio of the zodiac image - ie, being much wider than it is tall.

Image Texture coordinates run from 0.0 - 1.0 in both the horizontal and vertical direction, regardless of the actual resolution of the image. Since the 'blur' acts on these image texture coordinates this means that the effect of the blur in one direction is much more pronounced than that in the other direction. To address this, you need to scale the texture coordinates before the 'blur' (in this case by a factor of 12) and 'un-scale' them after. This can be easily achieved by using Mapping nodes with the X-scale set to '12' and '1/12' respectively.


I also simplified the blur node as the original seemed to also introduce an offset.

blur amended

This produces the following result :


Note that for this I also changed your mesh lights into Area Lamps. These produce better lighting and allow the number of samples to be considerably reduced with the same resultant quality.

  • $\begingroup$ Thanks for the pointers. I knew this had to do with the UV mapping somehow. As an aside, you stated that you changed the mesh lights to area lamps. I was under the impression based on some reading that cycles required mesh lighting because they had an extent. Is this not true? Should I be using area lamps and standard lighting objects when using cycles? I could make this its own thread, but just looking for a quick short answer. $\endgroup$ Nov 13, 2017 at 10:38
  • $\begingroup$ @JustaceClutter Cycles doesn’t require mesh light but they are useful in some situations - such as for ease of use or where the lamp needs to be a specific shape (eg, a spiral element in a light bulb). However, for square/rectangular uniform lights the area lamp will almost always be better than a mesh light as the renderer can optimise it and take shortcuts when determining the path to the lamp rather than having to trace all rays directly back to the surface. Generally you’ll get less noise and need fewer samples when using lamps rather than mesh lights (imo). $\endgroup$ Nov 13, 2017 at 13:10

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