POV-Ray : Newsgroups : povray.binaries.images : Bug with media in blobs? Server Time
9 Aug 2024 01:26:06 EDT (-0400)
  Bug with media in blobs? (Message 1 to 5 of 5)  
From: Gail Shaw
Subject: Bug with media in blobs?
Date: 12 Apr 2005 12:41:10
Message: <425bfa26@news.povray.org>
Is there a known bug involving media in blobs? The following code produces
lots of white dots around the boundry of the blob. The white dots only
appear if there is an object behind the blob. In the code below, comment out
the black box and the dots disappear.
If sturm is commented out of the blob declaration most of the white dots
vanish, but not all.

Using Pov-Ray 3.6.1.id8.win32

I could have sworn this didn't happen in 3.5

Anyone else seen this? Anyone know of a workaround?

// code

camera {
 location <0,0,-5>
 look_at <0,0,0>
 angle 20
}

blob {
 threshold 0.65
 sphere

  <0.5,0,0>,0.8,1
 }
 sphere

  <-0.5,0,0>,0.8,1
 }
 sturm
 hierarchy
 hollow
 material {
  texture {
   pigment {rgbt 1}
  }
  interior {
   media {
    emission <1,0.7,0.25>*2
   }
  }
 }
}

box {
 <-20,-20,20>,<20,20,21>
 pigment {rgb 0}
 hollow
 no_shadow
}


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Attachments:
Download 'MediaBlobBug1.jpg' (18 KB) Download 'MediaBlobBug.jpg' (25 KB)

Preview of image 'MediaBlobBug1.jpg'
MediaBlobBug1.jpg

Preview of image 'MediaBlobBug.jpg'
MediaBlobBug.jpg


 

From: St 
Subject: Re: Bug with media in blobs?
Date: 12 Apr 2005 14:06:39
Message: <425c0e2f@news.povray.org>
"Gail Shaw" <gsh### [at] sentechsacom> wrote in message 
news:425bfa26@news.povray.org...

> I could have sworn this didn't happen in 3.5

  Hi Gail - not sure if it's a bug or not, but I tried my 3.5, and as you 
can see from the image with the box, (gc1.jpg) they 'are' there, but closer 
to the surface than in your image. Without the box, (gc2.jpg), it's kind of 
reversed, and I see black spots that look like they're actually 'on' the 
surface to me.

   Sorry I can't help you more.

   ~Steve~


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Attachments:
Download 'gc1.jpg' (7 KB) Download 'gc2.jpg' (8 KB)

Preview of image 'gc1.jpg'
gc1.jpg

Preview of image 'gc2.jpg'
gc2.jpg


 

From: Gail Shaw
Subject: Re: Bug with media in blobs?
Date: 12 Apr 2005 16:10:20
Message: <425c2b2c@news.povray.org>
"St." <dot### [at] dotcom> wrote in message news:425c0e2f@news.povray.org...
>
>   Hi Gail - not sure if it's a bug or not, but I tried my 3.5, and as you
> can see from the image with the box, (gc1.jpg) they 'are' there, but
closer
> to the surface than in your image. Without the box, (gc2.jpg), it's kind
of
> reversed, and I see black spots that look like they're actually 'on' the
> surface to me.
>

Thanks. I looked around, but couldn't find any reports of this before.
Afaict, the more components in the blob, the worse it gets.

It's having a big impact on my current idea, and I don't have 3.5 installed
any longer. I'll have to see if I can find an install for it somewhere and
try this out.

Gail


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Attachments:
Download 'Candles.jpg' (24 KB)

Preview of image 'Candles.jpg'
Candles.jpg


 

From: Slime
Subject: Re: Bug with media in blobs?
Date: 12 Apr 2005 17:57:40
Message: <425c4454@news.povray.org>
This is probably just a problem with the accuracy of the blob solver; I
think it's not noticing the second (backside) surface near the edges, so it
thinks there's a long distance of media and makes it very bright as a
result. (In 3.5 this may have been diminished by anti-aliasing.)

A suggestion: Use a small box as your media container instead of a blob, and
then use a density{} in the media with the object pattern with the blob, so
that all points outside of the blob have no media.

 - Slime
 [ http://www.slimeland.com/ ]


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From: Gail Shaw
Subject: Re: Bug with media in blobs?
Date: 18 Apr 2005 16:33:36
Message: <426419a0@news.povray.org>
"Slime" <fak### [at] emailaddress> wrote in message
news:425c4454@news.povray.org...

> A suggestion: Use a small box as your media container instead of a blob,
and
> then use a density{} in the media with the object pattern with the blob,
so
> that all points outside of the blob have no media.
>

Thanks. That worked great. I completely forgot about object_pattern.

I'll post an updated WIP in a few days.

Gail


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