Looks like smooth triangle artifacts:

	http://tag.povray.org/povQandT/SmoothTriangleArtifact/index.html


HTH,
Florian

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"Thomas de Groot" <t.d### [at] internlDOTnet> wrote:

> Hasan,
> Looking at your image, I think that the sphere needs a couple of
> subdivisions more. Have you tried that, by applying smooth a couple of
> times?
>
> Thomas

Thomas, right, more subdivision solve this problem, but it creates extra
unnecessery vertex points. is there another way?

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"Hasan3" <PRO### [at] Yahoocom> schreef in bericht 
news:web.4562c9e1aedcdc51f50fb4000@news.povray.org...
>
> Thomas, right, more subdivision solve this problem, but it creates extra
> unnecessery vertex points. is there another way?
>

Well, in addition, there might be the problem mentioned by zorglub and 
Florian. Have a look at the mentioned documentation.

Thomas

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Florian Brucker wrote:
> Looks like smooth triangle artifacts:
> 
> 	http://tag.povray.org/povQandT/SmoothTriangleArtifact/index.html

  No, that's not it. The correct url is:

http://tag.povray.org/povQandT/TheShadowLineArtifact/index.html

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> Florian Brucker wrote:
>> Looks like smooth triangle artifacts:
> 
>   No, that's not it. The correct url is:
> 
> http://tag.povray.org/povQandT/TheShadowLineArtifact/index.html

Ah, OK. Thanks for pointing that out.


Regards,
Florian

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How about replacing the mesh with

    sphere{0, 1}

In all seriousness, POVRay SDL is extremely powerful and renders MUCH faster 
than meshes!

Rarius

"Hasan3" <PRO### [at] Yahoocom> wrote in message 
news:web.4562c9e1aedcdc51f50fb4000@news.povray.org...
> "Thomas de Groot" <t.d### [at] internlDOTnet> wrote:
>
>> Hasan,
>> Looking at your image, I think that the sphere needs a couple of
>> subdivisions more. Have you tried that, by applying smooth a couple of
>> times?
>>
>> Thomas
>
> Thomas, right, more subdivision solve this problem, but it creates extra
> unnecessery vertex points. is there another way?
>

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Warp <war### [at] tagpovrayorg> wrote:
> Florian Brucker wrote:
> > Looks like smooth triangle artifacts:
> >
> >  http://tag.povray.org/povQandT/SmoothTriangleArtifact/index.html
>
>   No, that's not it. The correct url is:
>
> http://tag.povray.org/povQandT/TheShadowLineArtifact/index.html

Warp, thanks, I will read this article...
Regards.

Hasan

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Florian Brucker <tor### [at] torfboldcom> wrote:
> > Florian Brucker wrote:
> >> Looks like smooth triangle artifacts:
> >
> >   No, that's not it. The correct url is:
> >
> > http://tag.povray.org/povQandT/TheShadowLineArtifact/index.html
>
> Ah, OK. Thanks for pointing that out.
>
>
> Regards,
> Florian

Florian, thanks for explanation. I have read this article :
"Firstly, don't think that it is a bug in POV-Ray. It isn't a bug, but a
real problem caused be the lighting model used in the renderer engine that
is quite difficult to surpass. It's not a problem in POV-Ray in particular,
but a problem in raytracing in general. Every raytracer will have this same
problem when using perturbed surface normals (unless there's some fix coded
into it)."

I rendered this object with other engines, for example Yafray :

I think, this is a deficiency for Povray..

Regards,
Hasan

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Attachments:
Download 'sphere2.jpg' (21 KB)

Preview of image 'sphere2.jpg'

"Hasan3" <PRO### [at] Yahoocom> wrote:

> Florian, thanks for explanation. I have read this article :
> "Firstly, don't think that it is a bug in POV-Ray. It isn't a bug, but a
> real problem caused be the lighting model used in the renderer engine that
> is quite difficult to surpass. It's not a problem in POV-Ray in particular,
> but a problem in raytracing in general. Every raytracer will have this same
> problem when using perturbed surface normals (unless there's some fix coded
> into it)."
>
> I rendered this object with other engines, for example Yafray :
>
> I think, this is a deficiency for Povray..

Clearly, the other engines have a fix for this coded in. But it is a problem
with the raytracing algorithm and modified normals, rather than a defect in
the way POV implements the algorithm (a bug).

I think there is at least one unofficial version of POV with a fix for this.
I think Slime-POV had one (but IIRC it's based on POV 3.5). There may be
others.

Tom

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POV-Sub, a modification of 3.6, might be able to fix this via run-time
subdivision:

http://www.cise.ufl.edu/~xwu/Pov-Sub/

It's still subdivision but your modelling software won't be generating the
extra faces.

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