POV-Ray : Newsgroups : povray.general : Smooth level for smooth_triangle. : Re: Smooth level for smooth_triangle. Server Time
3 Mar 2024 14:13:28 EST (-0500)
  Re: Smooth level for smooth_triangle.  
From: William F Pokorny
Date: 1 Dec 2023 08:49:50
Message: <6569e47e$1@news.povray.org>
On 11/25/23 04:56, Kenneth wrote:
> Yes, that is where those artifacts sometimes appear on a smooth-triangle object.
> I think it also depends on the lighting angle, and maybe even the size of the
> triangles.
> 
> What you are seeing is a known effect of raytracing the smooth normals when they
> are viewed at that raking angle. (I thought that there was a short technical
> explanation of this in the documentation, but I cannot find it.)

Not sure of any standard short explanation in our documentation, but you 
are right there are a whole set of mesh artifacts which come down to 
trying to represent smooth surfaces with patches. It's something which 
happens in all tooling. Search for shadow, termination, shading, etc, 
mesh artifacts with google.

Only general, 'minimization' solution I know is higher resolution 
meshes, especially where there is curvature. There are lots of patching 
/ artifact minimization approaches - always with trad-offs of one kind 
or another.

Aside: These termination artifacts exist with other mathematical 
representations of shapes too, they just tend to show up less frequently 
and forcefully than with lower resolution meshes. Though, suppose, a low 
resolution (accuracy) isosurface will have plenty of immediately 
apparent artifacts too!

Bill P.


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