I am trying to render a smooth mesh I have created (from a matlab script). I
have calculated all the vertex normals by averaging the vertex' adjacent faces'
normals and normalizing them.
I have checked (plotted in matlaba) and the normals appear to be correct.
However, when I render my mesh I encounter the problems described here:
http://wiki.povray.org/content/Knowledgebase:The_Shadow_Line_Artifact
http://wiki.povray.org/content/Knowledgebase:Smooth_Triangle_Artifact

So to solve all my problem I have to cancel shadows. Which is not
I am not sure I understand - is there no way to plot meshes without encountering
this issue, and being forced to remove shadows? Is there some way to use a
regular mesh (i.e not a "smooth" one) and make it appear to be smooth?

Post a reply to this message

On 19/05/2012 9:51 PM, noam wrote:
> So to solve all my problem I have to cancel shadows. Which is not
> I am not sure I understand - is there no way to plot meshes without encountering
> this issue, and being forced to remove shadows? Is there some way to use a
> regular mesh (i.e not a "smooth" one) and make it appear to be smooth?

You can subdivide your mesh using a utility called PoseRay.
https://sites.google.com/site/poseray/
Put your mesh into an INC file, load it into PoseRay as a 3D model. Go 
to the Groups tab and then the subdivision tab there. You can decide 
which options you want to select then subdivide the mesh. Export the 
modified mesh in the PovRay output tab. Again there are more options.
I generally use "Only export geometry and materials" and Left handed.

I hope this helps

-- 
Regards
     Stephen

Post a reply to this message

On 19-5-2012 22:51, noam wrote:
> I am trying to render a smooth mesh I have created (from a matlab script). I
> have calculated all the vertex normals by averaging the vertex' adjacent faces'
> normals and normalizing them.
> I have checked (plotted in matlaba) and the normals appear to be correct.
> However, when I render my mesh I encounter the problems described here:
> http://wiki.povray.org/content/Knowledgebase:The_Shadow_Line_Artifact
> http://wiki.povray.org/content/Knowledgebase:Smooth_Triangle_Artifact
>
> So to solve all my problem I have to cancel shadows. Which is not
> I am not sure I understand - is there no way to plot meshes without encountering
> this issue, and being forced to remove shadows? Is there some way to use a
> regular mesh (i.e not a "smooth" one) and make it appear to be smooth?
>
Have you tried to add double_illuminate to your mesh?

Thomas

Post a reply to this message

noam <nomail@nomail> wrote:
> So to solve all my problem I have to cancel shadows. Which is not
> I am not sure I understand - is there no way to plot meshes without encountering
> this issue, and being forced to remove shadows? Is there some way to use a
> regular mesh (i.e not a "smooth" one) and make it appear to be smooth?

  Usually using double_illuminate does not affect the appearance of closed
meshes (nor open ones if the interior surface is not visible), but removes
many of the artifacts caused by normal inversion.

  The only way to get rid of the shadow line artifact (or at least to
minimize it) without removing shadows altogether is to subdivide the mesh
into much smaller triangles.

-- 
                                                          - Warp

Post a reply to this message