Fan Spikes

[rcallicotte]

What are some usual causes that would cause these fan-like spikes in a fake-stone configuration?

[Kevin F]

Displacements of some sort. Whenever I get these I resort to turning things off one by one until the culprit shows. Then adjust accordingly if poss.

[rcallicotte]

Yeah.  Displacements...and I'll try that.  It's what I usually do, but it's so isolated.  This is a segment of a much larger image and is only one of two like this on opposite sides of the image.  Just seems very strange. 

This is not the recent Alpha version.

[Kevin F]

I'll bet it's a negative displacement somewhere, and just tweaking a tiny amount might just remove it. I had a similar one recently that produced the opposite to yours - the fan was reversed and produced tiny spikes fanning out from a single point. That was the result of a negative displacement combined with intersect underlying. Adjustments in both removed it.

[rcallicotte]

This was basically fixed by changing a Blending Shader's (Warping tab) - Less Warp at Feature Scale and Allow Vertical Warp.  This Cloud Shader was plugged into a Fake Stone's Blending Shader input.  I unchecked both of these Warping features.  This dramatically changed the unwanted results and almost completely removed unwanted Fan Spikes.  Some more twiddling with the displacement settings (lowering) here and there fixed anything else that was barely remaining.