Hi There

If you look to the attached images there are many notches (look at the red
ovals) in the object which is a very simple blob made of spheres.
If I rotate the object, the notches change place and size, so I'm quite sure
it is a bug in POVRay (version 3.1a).

Any one knows about this ?

Philippe

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Attachments:
Download 'Notches.jpg' (13 KB)

Preview of image 'Notches.jpg'

That does look peculiar. Did you try using the 'sturm' keyword in the
blob statement though?
But I haven't seen such a incomplete set of blobs before. In case you
haven't seen many of the recent animations using blobs, they don't have
any of this problem apparently. Nor have I ever seen them get as bad as
this. Trying to think from memory whether there was any fixes to blob{}
since 3.1a and only a texture placement fix comes to mind (I think).
Could that be it?


Ph Gibone wrote:
> 
> Hi There
> 
> If you look to the attached images there are many notches (look at the red
> ovals) in the object which is a very simple blob made of spheres.
> If I rotate the object, the notches change place and size, so I'm quite sure
> it is a bug in POVRay (version 3.1a).
> 
> Any one knows about this ?
> 
> Philippe
> 
>  [Image]

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 omniVERSE: beyond the universe
  http://members.aol.com/inversez/POVring.htm
 mailto:inv### [at] aolcom?PoV

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>That does look peculiar. Did you try using the 'sturm' keyword in the
>blob statement though?

Yes !

>But I haven't seen such a incomplete set of blobs before. In case you
>haven't seen many of the recent animations using blobs, they don't have
>any of this problem apparently. Nor have I ever seen them get as bad as
>this. Trying to think from memory whether there was any fixes to blob{}
>since 3.1a and only a texture placement fix comes to mind (I think).
>Could that be it?
>
I've tried several textures one very simple : texture{pigment {color
rgb<.8,.8,1>}}
Always the same

This image is one out of an animation set, an you can see the notches moving
and changing size just because the object is rotated !

Anyway here is the source :

#declare teta=texture{pigment {color rgb<.8,.8,1>}}
#declare tetb=texture{pigment{color rgb<1,.9,.9>} finish{reflection .95}}
#declare tetc=texture{pigment{color rgbf<1,1,1,1>}}


// create a smooth blobby shape
#declare Strengthval = 1 // (+ or -) strength of component's radiating
density
#declare radiuss = .45;
blob
{
  // threshold (0.0 < threshold <= StrengthVal) surface falloff threshold #
  threshold 0.61
     sphere {<0,.951057,0>, Strengthval, radiuss}
     sphere {<0,.425326,.850651> , Strengthval,radiuss}
     sphere {<.809017,.425326,.262866> , Strengthval,radiuss}
     sphere {<.5,.425326,-.688191> , Strengthval,radiuss}
     sphere {<-.5,.425326,-.688191> , Strengthval,radiuss}
     sphere {<-.809017,.425326,.262866> , Strengthval,radiuss}
     sphere {<0,-.951057,0> , Strengthval,radiuss}
     sphere {<0,-.425326,-.850651> , Strengthval,radiuss}
     sphere {<-.809017,-.425326,-.262866> , Strengthval,radiuss}
     sphere {<-.5,-.425326,.688191> , Strengthval,radiuss}
     sphere {<.5,-.425326,.688191> , Strengthval,radiuss}
     sphere {<.809017,-.425326,-.262866> , Strengthval,radiuss}
     sphere {<0,0,0>,Strengthval,radiuss/3 texture{teta}}
  sturm
  scale 2
  texture {tetb}
  rotate <clock, 2 * clock, 3*clock>

}

Thanks for taking time to answer

Philippe

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I tried removing the internal bounding hierarchy, but that didn't seem
to help either.  One thing I did notice is that there is a lot of
components overlapping.  I'm still not sure if there's a bug being shown
or if they just aren't overlapping the way expected. Here's the scene
with the components visible: 

#include "colors.inc"
camera {location <0, 0, -5>}

light_source {<10, 20, -30> color White}

#declare teta=texture{pigment {color rgb<.8,.8,1>}}
#declare tetb=texture{pigment{color rgb<1,.9,.9>} //finish{reflection
.95}
}
//#declare tetc=texture{pigment{color rgbf<1,1,1,1>}}


// create a smooth blobby shape
#declare Strengthval = 1 // (+ or -) strength of component's radiating
density
#declare radiuss = .45;
blob
{
  // threshold (0.0 < threshold <= StrengthVal) surface falloff
threshold #
  threshold 0.61
     sphere {<0,.951057,0>, Strengthval, radiuss}
     sphere {<0,.425326,.850651> , Strengthval,radiuss}
     sphere {<.809017,.425326,.262866> , Strengthval,radiuss}
     sphere {<.5,.425326,-.688191> , Strengthval,radiuss}
     sphere {<-.5,.425326,-.688191> , Strengthval,radiuss}
     sphere {<-.809017,.425326,.262866> , Strengthval,radiuss}
     sphere {<0,-.951057,0> , Strengthval,radiuss}
     sphere {<0,-.425326,-.850651> , Strengthval,radiuss}
     sphere {<-.809017,-.425326,-.262866> , Strengthval,radiuss}
     sphere {<-.5,-.425326,.688191> , Strengthval,radiuss}
     sphere {<.5,-.425326,.688191> , Strengthval,radiuss}
     sphere {<.809017,-.425326,-.262866> , Strengthval,radiuss}
     sphere {<0,0,0>,Strengthval,radiuss/3 texture{teta}}
  //sturm
  scale 2
  texture {tetb}
  rotate <clock, 2 * clock, 3*clock>
  hierarchy off

}

union {
sphere {<0,.951057,0>, Strengthval}
     sphere {<0,.425326,.850651> , Strengthval}
     sphere {<.809017,.425326,.262866> , Strengthval}
     sphere {<.5,.425326,-.688191> , Strengthval}
     sphere {<-.5,.425326,-.688191> , Strengthval}
     sphere {<-.809017,.425326,.262866> , Strengthval}
     sphere {<0,-.951057,0> , Strengthval}
     sphere {<0,-.425326,-.850651> , Strengthval}
     sphere {<-.809017,-.425326,-.262866> , Strengthval}
     sphere {<-.5,-.425326,.688191> , Strengthval}
     sphere {<.5,-.425326,.688191> , Strengthval}
     sphere {<.809017,-.425326,-.262866> , Strengthval}
     sphere {<0,0,0>,Strengthval}

       pigment {color rgbt <1, 1, 1, .9>}
       }

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It obviously is the last component (sphere) causing the problem. If
Strengthval is increased by multiplying it by 1.25 the artifacts more or
less disappear. The threshold, strength, radius adjusted in various ways
does not acheive the proper shape first made here without some pieces
missing.
So the interactions you need are disfunctional in that configuration for
some reason or another. May well be bug report material afterall.
But might not be an actual "bug" either and just the way blob works in
the current formulation.


-- 
 omniVERSE: beyond the universe
  http://members.aol.com/inversez/POVring.htm
 mailto:inv### [at] aolcom?PoV

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>I tried removing the internal bounding hierarchy, but that didn't seem
>to help either.  One thing I did notice is that there is a lot of
>components overlapping.  I'm still not sure if there's a bug being shown
>or if they just aren't overlapping the way expected. Here's the scene
>with the components visible:
>

If you give the "visible" components a texture which is totally transparent,
the notches disapear ! But this is a very dirty and time consuming
workaround

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>It obviously is the last component (sphere) causing the problem. If
>Strengthval is increased by multiplying it by 1.25 the artifacts more or
>less disappear. The threshold, strength, radius adjusted in various ways
>does not acheive the proper shape first made here without some pieces
>missing.
>So the interactions you need are disfunctional in that configuration for
>some reason or another. May well be bug report material afterall.
>
>
First remark : If you give the "visible" components a texture which is
totally transparent, the notches disapear ! But this is a very dirty and
time consuming workaround
Second remark : if you try with clock = 60 the notches are much bigger.
Third remark : the drawing you see is exactly what I want !


>But might not be an actual "bug" either and just the way blob works in
>the current formulation.

Hum... that's what I say to my clients.

Philippe

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