POV-Ray : Newsgroups : povray.general : Unwanted black spots in regular pattern : Re: Unwanted black spots in regular pattern Server Time: 16 Jun 2019 07:29:42 GMT
  Re: Unwanted black spots in regular pattern  
From: Norbert Kern
Date: 10 May 2019 21:25:00
"Jasper" <nomail@nomail> wrote:
> Hello everyone!
>
> I am trying to introduce photometric data files of luminaires (i.e. IESNA .ies
> or EULUMDAT .ldt) in Povray to get "correct" lighting distributions. In order to
> do so, I combine
>
> (1) a point light source
> (2) a sphere with radius 0.01 and spherical mapping of an image map (.png with
> the alpha channel used for transparency) which represents the lighting
> distribution for different angles.
>
> My camera view is from above, simulating a satellite view (Z-direction is "up")
> and assuming a simple planar object in xy. While the above-mentioned method
> works in most cases, it seems that for large coordinates (e.g. 1 000 000
> translation of both camera and luminaire in the xy plane), it no longer does (it
> becomes a regular point source), and some black dots appear in the resulting
> image. The strange thing is that it is not the case for translations of, e.g.,
> 100 000.
>
> Has anyone encountered similar problems and/or knows the reason for this?
>
> Jasper


There are other povray limits too - one is the combination of radiosity with
very small normals. Then black spots can occur everywhere in your scene.
Usually it helps to enlarge these small normals bor to delete them.
It would help to see a scene...

Norbert


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