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Hi,
are there working tools to speedup isosurface render time (at cost of
parsing time) by tringulize them?
--
http://www.raf256.com/3d/
Rafal Maj 'Raf256', home page - http://www.raf256.com/me/
Computer Graphics
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In article <Xns94DFB0D32188Araf256com@203.29.75.35>,
"Rafal 'Raf256' Maj" <spa### [at] raf256 com> wrote:
> are there working tools to speedup isosurface render time (at cost of
> parsing time) by tringulize them?
No. If you could reliably tessellate an isosurface, you could build two
rough meshes that bracket the isosurface between them, and use the
secant method to refine the root. Or use one mesh, and use Newton's
method with a numerically approximated derivative. The biggest problem
is that first step: tessellating isosurfaces reliably is hard, and many
of the algorithms are tied up in patents.
--
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: <chr### [at] tagpovrayorg>
http://tag.povray.org/
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in news:Xns94DFB0D32188Araf256com@203.29.75.35 Rafal 'Raf256' Maj wrote:
> are there working tools to speedup isosurface render time (at cost of
> parsing time) by tringulize them?
>
Yes. There was a macro posted to the newsgroups that does it. Als there
are several programms that do it. For example VTK:
http://public.kitware.com/VTK/
Another idea, that has come up here in the past, for speeding up
isosurfaces is to triangulate it first to a certain extend and then use
the mesh as the container object in the isosurface object.
Ingo
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cja### [at] earthlinknet news:cjameshuff-
D4E156.12012104052004@news.povray.org
> is that first step: tessellating isosurfaces reliably is hard, and many
> of the algorithms are tied up in patents.
Oh, f*ck USA, if this pattent madness continues, soon all programs will be
in normal "non-usa" version, and in version without half of features.
--
http://www.raf256.com/3d/
Rafal Maj 'Raf256', home page - http://www.raf256.com/me/
Computer Graphics
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On 4 May 2004 12:48:20 -0400, "Rafal 'Raf256' Maj" <spa### [at] raf256com> wrote:
> > is that first step: tessellating isosurfaces reliably is hard, and many
> > of the algorithms are tied up in patents.
>
> Oh, f*ck
Please, do not use that word here, even with "*". Thanks in advance.
> USA
Idea of patents is not limited to USA. http://www.uprp.pl/
> if this pattent madness continues
What's wrong in patenting intelectual property in general ?
If somebody has discovered something and he spend years for studying math to
achive it, why he can't get reward for those years of studying?
I understand that's inconvenient from our point of view, but also I understand
purpose of the patents.
> soon all programs will be
> in normal "non-usa" version, and in version without half of features.
So, you like globalisation, I like diversity ;-)
Follow-up set.
ABX
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Rafal 'Raf256' Maj wrote:
>
> Oh, f*ck USA, [...]
This is completely inappropriate here, please read the AUP, especially
point 3. It does not really matter but such a statement is also a
strong sign for ignorance on your side.
Christoph
--
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 01 May. 2004 _____./\/^>_*_<^\/\.______
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Wasn't it Rafal 'Raf256' Maj who wrote:
>Hi,
>are there working tools to speedup isosurface render time (at cost of
>parsing time) by tringulize them?
Take a look at Kevin Loney's Approximation Macro, and Jaap Frank's
faster modified version, which construct mesh2 objects that approximate
isosurfaces. In many cases, the total time required to parse and render
the approximation is greater than the time taken to render a real
isosurface, but there could well be situations where using the
approximation could be faster, for example if the same isosurface were
to appear in each frame of an animation it would only need to be parsed
once and then the data could be read from a file for all the subsequent
frames.
See <http://www.econym.demon.co.uk/isotut/approx.htm>
If you can recast your isosurface equation in parametric form, then you
can use Ingo Janssen's approximation macro which does run much faster
than the corresponding isosurface.
See <http://www.econym.demon.co.uk/isotut/param.htm>
--
Mike Williams
Gentleman of Leisure
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> There was a macro posted to the newsgroups that does it.
I suppose you're referring to Kevin Loney's tool. He posted this a while
back, maybe a year or so. It works nicely (on the shapes I've tried) though
it's parsing slowly and creates some overlaps in triangles. But if you save
the result as an .OBJ file, you can use another application (such as 3dsMax)
to clean-up and optimise the mesh. I've tried this and the result renders
very fast and looks great, but of course you need to consider the extra
memory it consumes.
Regards,
Hugo
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