I've written a Cycles node tree to convert rectangular (X,Y) to polar coordinates (R,theta) as the basis for a procedural texture with radial symmetry.

However, there is a seam in the texture where theta jumps in value (-pi -> pi or 0 -> 2pi).

What are some of the techniques for eliminating this seam? I have found one method that uses a blended overlap region. Are there others?

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    $\begingroup$ Have a look at this: blender.stackexchange.com/a/45169/7777 $\endgroup$ – Jaroslav Jerryno Novotny Jan 27 '16 at 13:26
  • $\begingroup$ That's useful for textures with regularity. Thank you for including the details of the node groups for the cylindrical and spherical projections. I will compare them to the node groups I created. I plan to use Noise, Voronoi, or Musgrave textures that do not repeat like the chevron in your solution. I expect the discontinuity at -pi (or 2pi) will be visible. $\endgroup$ – astrogeek Jan 27 '16 at 16:28
  • $\begingroup$ Yes, when the texture is not tiled you will have a seam. $\endgroup$ – Jaroslav Jerryno Novotny Jan 27 '16 at 17:28
  • $\begingroup$ I am curious as if you have found a solution to this issue... $\endgroup$ – Eranekao Mar 13 '16 at 4:01
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    $\begingroup$ @VilkoL I haven't gotten back to this issue yet. I'm currently hiding the seam by using a texture with a really large scale (i.e. small-scale features) so the seam is largely mixed in among the many variations in the texture. I found this wonderful page paulbourke.net/texture_colour/edgeblend and intended to use his algorithm. The middle-to-last part of the page gets into the details. $\endgroup$ – astrogeek Mar 18 '16 at 1:24

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