POV-Ray : Newsgroups : povray.general : Smooth level for smooth_triangle. : Re: Smooth level for smooth_triangle. Server Time
3 Mar 2024 08:39:20 EST (-0500)
  Re: Smooth level for smooth_triangle.  
From: Alain Martel
Date: 25 Nov 2023 13:16:49
Message: <65623a11$1@news.povray.org>
Le 2023-11-25 à 12:40, GioSeregni a écrit :
> "GioSeregni" <gms### [at] hotmailcom> wrote:
>> "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.
> Bug hacked?
> old sprites concept? I'm under no illusions, I'll do more tests, but in this way
> I don't see the bug anymore

Even better :
interior_texture{pigment{rgbt 1}}
interior_texture{pigment{rgbf 1}}

That way, no need to use any image file.

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