POV-Ray : Newsgroups : povray.general : Isosurface troble Server Time
6 Aug 2024 00:16:47 EDT (-0400)
  Isosurface troble (Message 13 to 22 of 32)  
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From: Christoph Hormann
Subject: Re: Isosurface troble
Date: 7 Aug 2002 09:46:57
Message: <3D5124D2.22BBCFF6@gmx.de>
Warp wrote:
> 
>   Of course this raises the question why do you want to use an isosurface
> to create a heightfield at all?

Using image maps in isosurfaces can be very useful if you want to add a
fine structure to a rough geometry defined by an image.

Christoph

-- 
POV-Ray tutorials, IsoWood include,                 
TransSkin and more: http://www.tu-bs.de/~y0013390/  
Last updated 03 Aug. 2002 _____./\/^>_*_<^\/\.______


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From: Warp
Subject: Re: Isosurface troble
Date: 7 Aug 2002 10:36:17
Message: <3d513060@news.povray.org>
Christoph Hormann <chr### [at] gmxde> wrote:
> Using image maps in isosurfaces can be very useful if you want to add a
> fine structure to a rough geometry defined by an image.

  You could do that with a mesh as well, and get a much faster rendering. :)

-- 
#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: Christoph Hormann
Subject: Re: Isosurface troble
Date: 7 Aug 2002 11:25:54
Message: <3D513C00.3BE6D954@gmx.de>
Warp wrote:
> 
> > Using image maps in isosurfaces can be very useful if you want to add a
> > fine structure to a rough geometry defined by an image.
> 
>   You could do that with a mesh as well, and get a much faster rendering. :)
> 

That's quite difficult and it would take incredible amounts of memory.

Christoph

-- 
POV-Ray tutorials, IsoWood include,                 
TransSkin and more: http://www.tu-bs.de/~y0013390/  
Last updated 03 Aug. 2002 _____./\/^>_*_<^\/\.______


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From: Peter Popov
Subject: Re: Isosurface troble
Date: 7 Aug 2002 12:50:08
Message: <pkj2lu8qbf9l05ccdf8lpd116lme0ufe7v@4ax.com>
On 6 Aug 2002 17:02:17 -0400, Warp <war### [at] tagpovrayorg> wrote:

>  Of course this raises the question why do you want to use an isosurface
>to create a heightfield at all?

Because I want to have the sides of the HF as well. I spent a whole
afternoon trying to resurrect the old HF clipping trick that I used so
often in the past, but I just can't get it to work anymore.

The render times are not impossible with a 16-bit grayscale PNG image
as a source and interpolate 4. The render time for my last picture was
just over 16 hours with two such isosurfaces, one of them refractive
and filled with media, and nested in a refractive CSG object, and well
over 5000000 photons. 16hr is not that bad for such a monster,
especially on a puny computer like my 400 MHz K6.

I ditched the idea and used a ridged multifractal function instead,
just because I couldn't make the HF I wanted in WorldMachine.


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] vipbg
TAG      e-mail : pet### [at] tagpovrayorg


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From: Warp
Subject: Re: Isosurface troble
Date: 7 Aug 2002 15:00:13
Message: <3d516e3d$1@news.povray.org>
Christoph Hormann <chr### [at] gmxde> wrote:
> That's quite difficult and it would take incredible amounts of memory.

  Subdividing a mesh is not difficult at all, and it does not take
"incredible amounts of memory", just the extra memory needed for the
extra vertex points and triangles.

-- 
#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: Warp
Subject: Re: Isosurface troble
Date: 7 Aug 2002 15:01:22
Message: <3d516e82@news.povray.org>
Peter Popov <pet### [at] vipbg> wrote:
> Because I want to have the sides of the HF as well.

  Sorry, but I didn't understand this.

-- 
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -


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From: Christoph Hormann
Subject: Re: Isosurface troble
Date: 7 Aug 2002 15:21:27
Message: <3D517335.6A434EDC@gmx.de>
Warp wrote:
> 
> [...]
> 
>   Subdividing a mesh is not difficult at all, and it does not take
> "incredible amounts of memory", just the extra memory needed for the
> extra vertex points and triangles.
> 

Subdividing a mesh and displacing in normal direction is not camparable to
distorting an isosurface function and it can take enormeous amounts of
memory to generate a mesh of such a resolution.

Christoph

-- 
POV-Ray tutorials, IsoWood include,                 
TransSkin and more: http://www.tu-bs.de/~y0013390/  
Last updated 03 Aug. 2002 _____./\/^>_*_<^\/\.______


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From: Christopher James Huff
Subject: Re: Isosurface troble
Date: 7 Aug 2002 16:11:58
Message: <chrishuff-66C5CA.15020107082002@netplex.aussie.org>
In article <3d5084d3@news.povray.org>, Warp <war### [at] tagpovrayorg> 
wrote:

> Christopher James Huff <chr### [at] maccom> wrote:
> > no trouble with faceting
> 
>   He is using an image to create the heightfield...

And what does that have to do with faceting?

-- 
Christopher James Huff <chr### [at] maccom>
POV-Ray TAG e-mail: chr### [at] tagpovrayorg
TAG web site: http://tag.povray.org/


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From: Warp
Subject: Re: Isosurface troble
Date: 7 Aug 2002 16:12:58
Message: <3d517f48@news.povray.org>
Christoph Hormann <chr### [at] gmxde> wrote:
> Subdividing a mesh and displacing in normal direction is not camparable to
> distorting an isosurface function

  Why not?

-- 
#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: Christopher James Huff
Subject: Re: Isosurface troble
Date: 7 Aug 2002 16:13:18
Message: <chrishuff-2D8F4D.15032107082002@netplex.aussie.org>
In article <3d516e82@news.povray.org>, Warp <war### [at] tagpovrayorg> 
wrote:

> > Because I want to have the sides of the HF as well.
> 
>   Sorry, but I didn't understand this.

The sides of the POV height_field primitive are open, it is just a 
sheet. He wants them to be closed, something that I've wanted before too.

It should be possible to get the desired effect using an intersection of 
a height field and a box.

-- 
Christopher James Huff <chr### [at] maccom>
POV-Ray TAG e-mail: chr### [at] tagpovrayorg
TAG web site: http://tag.povray.org/


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