Hello, I have a qustion concerning the great program sPatch.

I have made a simple object in sPatch 1.51, but when rendering this
object in POV-Ray I have noticed some strange black dots appering on the
obejct. It looks like there are some "glitches" between the different
surfaces of the obejct.

Does anyone have any tips how to get rid of thees black pixels?

Concerning sPatch, does anyone know if there are any future development
plans for the program? What new functionality could be useful in a new
release of sPatch?

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The only thing that might be causing it I know of is the 'flatness' in
the 'bicubic_patch' which sPatch exports for POV-Ray. It should be 0
though so that probably isn't the problem (I guess). I have version 1.5
here not 1.51 (unless that 1 was a mistake) so maybe there's a
preference change for flatness. Have you tried slightly different
viewing angles to see how the model surface changes?


Paul Johnsson wrote:
> 
> Hello, I have a qustion concerning the great program sPatch.
> 
> I have made a simple object in sPatch 1.51, but when rendering this
> object in POV-Ray I have noticed some strange black dots appering on the
> obejct. It looks like there are some "glitches" between the different
> surfaces of the obejct.
> 
> Does anyone have any tips how to get rid of thees black pixels?
> 
> Concerning sPatch, does anyone know if there are any future development
> plans for the program? What new functionality could be useful in a new
> release of sPatch?

-- 
 omniVERSE: beyond the universe
  http://members.aol.com/inversez/homepage.htm
 mailto://inversez@aol.com?Subject=PoV-News

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I actually do have the 1.51 here too.
You might want to turn up the 'max_trace_level' at least if not done so
already. Is the model being textured using transparency? Then for sure
do so.
The sPatch seems to be in limbo, permanently. A email to the author
might come up with a response, but believe I had heard it wasn't going
anywhere anytime soon.
You mention functionality, vertex magnetism would be kind of neat.
What's it called in other modellers? Metaballs, NURBS or some such thing
(how am I supposed to know?). Anyway, it would be a great feature.


Bob Hughes wrote:
> 
> The only thing that might be causing it I know of is the 'flatness' in
> the 'bicubic_patch' which sPatch exports for POV-Ray. It should be 0
> though so that probably isn't the problem (I guess). I have version 1.5
> here not 1.51 (unless that 1 was a mistake) so maybe there's a
> preference change for flatness. Have you tried slightly different
> viewing angles to see how the model surface changes?
> 
> Paul Johnsson wrote:
> >
> > Hello, I have a qustion concerning the great program sPatch.
> >
> > I have made a simple object in sPatch 1.51, but when rendering this
> > object in POV-Ray I have noticed some strange black dots appering on the
> > obejct. It looks like there are some "glitches" between the different
> > surfaces of the obejct.
> >
> > Does anyone have any tips how to get rid of thees black pixels?
> >
> > Concerning sPatch, does anyone know if there are any future development
> > plans for the program? What new functionality could be useful in a new
> > release of sPatch?
>

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Metaballs are blobs, NURBS are Non Uniform Rational Bezier Splines, as
if that alone means anything(I have zero experience with them), but I
have never heard of "vertex magnetism". Does it act like a spherical
blob component is at each vertex?

Post a reply to this message

What I was trying in vain to describe :) is something that Bryce has (I
believe, though I'm having trouble locating any info), the vertex points
in a model can be attracted or repelled in a chosen area. They call it
something like a Magnet Tool.


Chris Huff wrote:
> 
> Metaballs are blobs, NURBS are Non Uniform Rational Bezier Splines, as
> if that alone means anything(I have zero experience with them), but I
> have never heard of "vertex magnetism". Does it act like a spherical
> blob component is at each vertex?

-- 
 omniVERSE: beyond the universe
  http://members.aol.com/inversez/homepage.htm
 mailto://inversez@aol.com?Subject=PoV-News

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Bob Hughes wrote:
> 
> What I was trying in vain to describe :) is something that Bryce has (I
> believe, though I'm having trouble locating any info), the vertex points
> in a model can be attracted or repelled in a chosen area. They call it
> something like a Magnet Tool.

For a mesh deformation to see:
http://www.flash.net/~drsledge/manual/manual.htm

-- 
Ken Tyler
  
mailto://tylereng@pacbell.net
http://home.pacbell.net/tylereng/links.htm

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The povray documentation answers the question much precisely:

There are both advantages and disadvantages to using a non-zero flatness.
...
The biggest disadvantage is that if POV-Ray stops subdividing at a
particular level on one part of the patch and at a different level on an
adjacent part of the patch there is the potential for cracking. This is
typically visible as spots within the patch where you can see through. How
bad this appears depends very highly on the angle at which you are viewing
the patch.

  You can try setting the flatness smaller (or even 0) or increasing
u_steps and v_steps.

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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