POV-Ray : Newsgroups : povray.general : Mesh rendering artifacts : Re: Mesh rendering artifacts Server Time
26 Mar 2023 21:42:44 EDT (-0400)
  Re: Mesh rendering artifacts  
From: Bald Eagle
Date: 1 Feb 2023 20:25:00
Message: <web.63db100c249f00761f9dae3025979125@news.povray.org>
"yesbird" <nomail@nomail> wrote:
> Hi, guys.
> May be am asking too many questions, but I am new to POV and before asking
> trying everything I can not for only one hour.
> Could you suggest the way of getting rid of artifact, markered on this image,

I knew this was going to be a debugging nightmare, so I made a nice big Gin &
Tonic, got out the Italian olive medley, and started fiddling.

I have found out what your problem is, and it's directly related to what MatLab
exports, and how you're trying to render it in POV-Ray.

At first glance, it sort of seemed to me that some of the colors were getting
"dragged" up into places that they shouldn't be.   And that's sort of what's
happening.  I outlined each triangle to show the edges, and there was a
pronounced matching of the colors with the edges of the grid - parabolas of
color that followed the vertical slicing of the surface.

What you WANT is a nice, gradient y pattern like I first suggested.
What you're getting is a 3-color interpolation of the 3 vertex colors, which is
blending colors from the wrong regions, and thus giving you the funny colors.

What I did was "shrink" the triangles a bit, and plot spheres with the vertex
colors at each vertex.   Then I made a cylinder with a gradient going from the
color of one vertex to the color of the other vertex.  Then I did the same
thing, only connecting all of the vertices to the triangle's center.

This shows the geometry and the colors along with the way the colors are

_I think you can fix this by changing the axes that you're slicing along._

I would also suggest that you orient all of you stuff the way POV-Ray does -
with a left-handed coordinate system, +x to the right, +y as up, and +z going
into the screen and away from you.

- BE

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