POV-Ray : Newsgroups : povray.general : Artifacts with media blobs and CSG boxes Server Time
31 Jul 2024 16:25:42 EDT (-0400)
  Artifacts with media blobs and CSG boxes (Message 1 to 6 of 6)  
From: Christian Froeschlin
Subject: Artifacts with media blobs and CSG boxes
Date: 21 Jan 2007 16:35:00
Message: <web.45b3dbf2f3273a327878ff140@news.povray.org>
Hello,

I have encountered two situations in which the render contains
some pixel artifacts (and it doesn't seem to be incident surfaces
or maximum trace level). Tested using POV-Ray 3.6 and Mega-Pov 1.2.1
on Windows XP, minimum sample code for each case is included below.

Also, does anyone else have problems logging into the forums?
I couldn't log in using Netscape 7.2, and after resorting to
IE6 (*shudder*), I was prompted to login again after clicking
"Preview" and lost the message text on the first attempt.


Case 1: Transparent blobs filled with media, you should see some
        black pixels near the top of the white blob. Adding the
        sturm keyword makes matters a lot worse.


global_settings
{
  assumed_gamma 1.0
  max_trace_level 10
}


camera
{
  location  <0.0, 1.0, -5.0>
  look_at   <0.0, 1.0,  0.0>
  angle 90
}

light_source {< -10,  10, -10> color rgb 1}

blob
{
  threshold 0.6
  sphere {0, 5, 1 scale <1, 0.3, 1>}
  sphere {0, 1, 1 scale <1, 0.8, 1> translate y}

  hollow pigment {color rgbt 1}

  interior
  {
    media
    {
      scattering {1, color rgb 0.5}
    }
  }
}


-------------------------------------------------------------------


Case 2: Box which has been subtracted from twice in CSG difference
        operations (even if 0 objects were subtracted, but only if
        some other objects are around, so the code below looks a
        bit silly). You should see a lot of white pixels in the
        box edges, although everything should be ambient level.


global_settings
{
  assumed_gamma 1.0
}

camera
{
  location  1
  look_at   0
}

light_source {< -10,  10, -10> color 50}

sphere {5,0.1}  /* Dummy object */

difference
{
  difference
  {
    box {0, 2}
  }
  pigment {color rgb 1}
}

sphere {5,0.2} /* Dummy object */


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From: FrogRay
Subject: Re: Artifacts with media blobs and CSG boxes
Date: 21 Jan 2007 23:20:00
Message: <web.45b43a9352b6697e52677b7d0@news.povray.org>
"Christian Froeschlin" <chr### [at] chrfrde> wrote:
> Hello,

> Also, does anyone else have problems logging into the forums?
> I couldn't log in using Netscape 7.2, and after resorting to
> IE6 (*shudder*), I was prompted to login again after clicking
> "Preview" and lost the message text on the first attempt.

I haven't had a look at your POV problem yet, although blobs filled with
media sounds interesting - I've never tried that!


As for problems logging in...
I did have some problems once.  It was because I had set my browser to
accept cookies from povray.org but not news.povray.org.   If you can get in
using IE but not NetScape - this might be your problem.  Don't know about
the having to log in again when previewing message.  That sound's like
either a server glitch, timeout or connection problem.


Post a reply to this message

From: Christian Froeschlin
Subject: Re: Artifacts with media blobs and CSG boxes
Date: 22 Jan 2007 16:31:49
Message: <45b52d45$1@news.povray.org>
FrogRay wrote:

> I haven't had a look at your POV problem yet, although blobs filled with
> media sounds interesting - I've never tried that!

Thought it might make a fluffy picture book cloud ;)

> I did have some problems once.  It was because I had set my browser to
> accept cookies from povray.org but not news.povray.org.  

Ah, that could have been it. But since I now realized this thing has a
real news server, I just use a news reader instead of the web interface.


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From: Christian Froeschlin
Subject: Re: Artifacts with media blobs and CSG boxes
Date: 29 Jan 2007 11:07:35
Message: <45be1bc7$1@news.povray.org>
Christian Froeschlin wrote:

> I have encountered two situations in which the render contains
> some pixel artifacts (and it doesn't seem to be incident surfaces
> or maximum trace level). Tested using POV-Ray 3.6 and Mega-Pov 1.2.1
> on Windows XP, minimum sample code for each case is included below.

I would appreciate it if someone could verify that the described effect
also occurs on his/her system and is not a silly problem of my sample
code so I could report this as a bug. Thank you.


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From: Stephen
Subject: Re: Artifacts with media blobs and CSG boxes
Date: 29 Jan 2007 11:30:00
Message: <web.45be202552b6697ef1cb1e660@news.povray.org>
Christian Froeschlin <chr### [at] chrfrde> wrote:
> Christian Froeschlin wrote:
>
> > I have encountered two situations in which the render contains
> > some pixel artifacts (and it doesn't seem to be incident surfaces
> > or maximum trace level). Tested using POV-Ray 3.6 and Mega-Pov 1.2.1
> > on Windows XP, minimum sample code for each case is included below.
>
> I would appreciate it if someone could verify that the described effect
> also occurs on his/her system and is not a silly problem of my sample
> code so I could report this as a bug. Thank you.

Confirmed

Stephen


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From: Charles C
Subject: Re: Artifacts with media blobs and CSG boxes
Date: 30 Jan 2007 00:15:00
Message: <web.45bed3e652b6697e2f60260@news.povray.org>
"Christian Froeschlin" <chr### [at] chrfrde> wrote:

> Also, does anyone else have problems logging into the forums?

I used to have a problem where it would repeatedly give me the log-in prompt
if I'd correctly type my password, or tell me that I'd typed an invalid name
or password if in fact I'd mis-typed it.  I think it might've been a latency
issue with my slow internet connection which has one way or another gone
away.

> I couldn't log in using Netscape 7.2, and after resorting to
> IE6 (*shudder*), I was prompted to login again after clicking
> "Preview" and lost the message text on the first attempt.

For this part, I think that's normal - it just means you took too long
typing.  When that happens, what I do is click "Back", copy the entire
contents of the text box and then hit "Back" again to get to the original
message I was replying to, or where I can hit new-message-to-this-group if
it's a new post.  I.e. start over, but this time there's no typing to do.

PS I think I'm seeing the same thing when rendering the code (unofficial
3.6.0).

Charles


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