POV-Ray : Newsgroups : povray.general : Smooth level for smooth_triangle. : Re: Smooth level for smooth_triangle. Server Time
3 Mar 2024 07:26:25 EST (-0500)
  Re: Smooth level for smooth_triangle.  
From: GioSeregni
Date: 25 Nov 2023 05:45:00
Message: <web.6561cfc684c692a3276109cb59126100@news.povray.org>
"Kenneth" <kdw### [at] gmailcom> wrote:
> "GioSeregni" <gms### [at] hotmailcom> wrote:
> > "Bald Eagle" <cre### [at] netscapenet> wrote:
> > >
> > > And if you DO see red there, then try moving the camera around, and viewing it
> > > from different angles - because it may just disappear and pop up in different
> > > areas.
> >
> > It seems that they always arise on the
> > perimeter of the volumes (in positions tangential to the cone of vision)...
>
> 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.) The camera is
> picking up the unlighted (black) interior of the object.
>
> If I make a low-rez height_field and add the 'smooth' keyword, the same thing
> happens. The interior_texture trick is one way to try and make these artifacts
> less noticable. Or try adding the 'double_illuminate' keyword to the object. If
> I recall, this was a recommended 'fix' for the problem. It seems to work most of
> the time, but not in every situation.

Ok, thank! I am working on .. it does not seems by light position, but by the
angle between WP and smooth_triangle (s) ...
Many thanks again!
G.


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