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From: Philippe Debar
Subject: Grid artifact in f_noise3d isosurface
Date: 22 Jun 2002 12:40:19
Message: <3d14a873@news.povray.org>
Toying with isosurfaces (pov v3.5RC6), I found a quite visible grid
artifact... I don't know what to make of it. Should I make a bug report ? It
is so basic [just function{-z+f_noise3d(x,y,z)}] that I find it very
unlikely that it is unknown. But searching with http://news.povray.org
yielded no answer... So, could anyone check this
http://web.wanadoo.be/wbrp0009/pov/main.html and tell me what to do with it.


Povingly,


Philippe


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From: Jan Walzer
Subject: Re: Grid artifact in f_noise3d isosurface
Date: 22 Jun 2002 12:47:57
Message: <3d14aa3d$1@news.povray.org>
have you played with accuracy settings ?


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From: Philippe Debar
Subject: Re: Grid artifact in f_noise3d isosurface
Date: 22 Jun 2002 13:03:54
Message: <3d14adfa@news.povray.org>
"Jan Walzer" <jan### [at] lzernet> wrote in message
news:3d14aa3d$1@news.povray.org...
> have you played with accuracy settings ?


Yes. It's one of the first thing I tried after checking the gradient /
avaluate. The grid is visible from accuracy at accuracy 1e-1, 1e-2, ...,
1e-6. I went no further.


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From: Marc-Hendrik Bremer
Subject: Re: Grid artifact in f_noise3d isosurface
Date: 22 Jun 2002 13:58:30
Message: <3d14bac6@news.povray.org>
"Philippe Debar" <phd### [at] belgacomnet> schrieb im Newsbeitrag
news:3d14a873@news.povray.org...

> So, could anyone check this
> http://web.wanadoo.be/wbrp0009/pov/main.html and tell me what to do with
it.

For what it's worth, I would say: Make a bug report in p.b-t. They will fix
it, or tell you that this is the way they want it to work. There were some
changes to the noise-functions in RC6, as changes.txt tells - maybe
something went wrong. Judging from the web-page you made, f_noise looses a
lot of it's functionality if it stays the way it is - who would want some
noise with a grid?

But I did no own test so, I really don't know what it's worth. At least I
can't remember such artefacts in MegoPov or earlier Versions of 3.5.

Greetings,

Marc-Hendrik


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From: Warp
Subject: Re: Grid artifact in f_noise3d isosurface
Date: 22 Jun 2002 14:12:38
Message: <3d14be16@news.povray.org>
Philippe Debar <phd### [at] belgacomnet> wrote:
> Toying with isosurfaces (pov v3.5RC6), I found a quite visible grid
> artifact... I don't know what to make of it. Should I make a bug report ? It
> is so basic [just function{-z+f_noise3d(x,y,z)}] that I find it very
> unlikely that it is unknown.

  This is known to the team, so no need to report it.
  The exact reason for this is not clear (it might not be a bug at all, but
the noise_generator 3 might just produce that; better alternatives may be
studied).
  Use noise generators 1 or 2 instead (I think it was f_noise_generator()
if you want to use another noise generator instead of the default, which
is 3).

-- 
#macro N(D)#if(D>99)cylinder{M()#local D=div(D,104);M().5,2pigment{rgb M()}}
N(D)#end#end#macro M()<mod(D,13)-6mod(div(D,13)8)-3,10>#end blob{
N(11117333955)N(4254934330)N(3900569407)N(7382340)N(3358)N(970)}//  - Warp -


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From: Philippe Debar
Subject: Re: Grid artifact in f_noise3d isosurface
Date: 22 Jun 2002 14:32:10
Message: <3d14c2aa@news.povray.org>
"Warp" <war### [at] tagpovrayorg> wrote in message
news:3d14be16@news.povray.org...

>   This is known to the team, so no need to report it.

Mmmh ! I guessed so ;-)

>   The exact reason for this is not clear (it might not be a bug at all,
but
> the noise_generator 3 might just produce that; better alternatives may be
> studied).

I've got the feeling we'll have to wait for 3.5b or MegaPov-the-next-gen.

>   Use noise generators 1 or 2 instead (I think it was f_noise_generator()
> if you want to use another noise generator instead of the default, which
> is 3).

Noise gen 1 and 2 suffer from the same problem, see
http://web.wanadoo.be/wbrp0009/pov/main.html, 5th and 6th images.
:-(


Philippe


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From: Thorsten Froehlich
Subject: Re: Grid artifact in f_noise3d isosurface
Date: 22 Jun 2002 15:14:15
Message: <3d14cc87@news.povray.org>
In article <3d14a873@news.povray.org> , "Philippe Debar" 
<phd### [at] belgacomnet> wrote:

> http://web.wanadoo.be/wbrp0009/pov/main.html

It would really help if the image source URLs would be valid.  That is
spaces encoded as required so they work outside broken browsers like
Internet Explorer...

    Thorsten


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From: Apache
Subject: Re: Grid artifact in f_noise3d isosurface
Date: 22 Jun 2002 17:14:54
Message: <3d14e8ce$1@news.povray.org>
I had no problems with the URL. (IE6, win2k)

--
Apache
POV-Ray Cloth experiments: http://geitenkaas.dns2go.com/experiments/
Email: apa### [at] yahoocom
ICQ: 146690431


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From: Jan Walzer
Subject: Re: Grid artifact in f_noise3d isosurface
Date: 22 Jun 2002 18:52:22
Message: <3d14ffa6$1@news.povray.org>
"Apache" <apa### [at] yahoocom> wrote:
> I had no problems with the URL. (IE6, win2k)

did you read Thorstens whole answer ?
he said:
> "spaces encoded as required so they work outside broken
>  browsers like..."


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From: Philippe Debar
Subject: Re: Grid artifact in f_noise3d isosurface
Date: 22 Jun 2002 21:04:36
Message: <3d151ea4@news.povray.org>
Ooops ! Sorry, my first web experience. I plead ignorance. I change that
right away (and I thought I
could go to sleep now...*sigh*). I removed the spaces as I do not know how
they have to be encoded - and right know, I choose sleep over knowledge
;-) I also removed uppercases, just in case <g>.


Philippe


"Thorsten Froehlich" <tho### [at] trfde> wrote in message
news:3d14cc87@news.povray.org...
> In article <3d14a873@news.povray.org> , "Philippe Debar"
> <phd### [at] belgacomnet> wrote:
>
> > http://web.wanadoo.be/wbrp0009/pov/main.html
>
> It would really help if the image source URLs would be valid.  That is
> spaces encoded as required so they work outside broken browsers like
> Internet Explorer...
>
>     Thorsten
>


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