On 5/15/19 10:04 AM, William F Pokorny wrote:
> On 5/13/19 7:29 AM, Jasper wrote:
...
> 
> Hmm, I have to say I'm curious about the regularity of those black 
> spots. The numerical issues I've hit are usually noisier - or completely 
> black/invisible/something when a hard numerical limit is hit.
> 
> Any chance I could get a smallish test case posted to one of the scene 
> file groups? I'll stick it in my POVRay_Issues directory and at least 
> take a quick look if not now a deep one.
> 

I dug out some work I was doing early in 2018 where I was using a 
user_defined functional pigment as the sphere's texture around the 
light. At the time I was thinking it might be a good way to define 
texture maps or even use use such 'noisy lights' in a scene instead of - 
or in addition to - traditional materials. In particular I was thinking 
about human skin. The set up is similar to yours except how the texture 
is defined.

There was also recent discussion around user_defined cameras and 
transforms and it hit me I'd never tested moving my user_defined pigment 
around though I fully hoped that technique would work with simple 
transforms. It appears it does not - see the attached image 1e5 column. 
Not shown, but 1e3 results similarly corrupted and that movement well 
away from numerical issues.

So, I got two issues for the price of trying to verify yours! Good news 
is I now have a small test scene for both.

Bill P.

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