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Felix Petriconi wrote:
> Are there other tools or programs wich support the possibility to export
> bicubic patches into PovRay format?
SPatch is the preferred utility of many people and is highly capable.
http://www.cableone.net/alyson/spatch.html
> Nieminen, You asked for the advantages of NURBS. I do not know the maths
> but there have to be a reason, that proffessional programs like Maya,
> Houdini and others support NURBS. (This might not be the best argument,
> but it supports a little bit that NURBS have advantages against bicubic
> patches. Greetings, Felix
I think one of the main advantages with nurbs is that the format is good for
modelling complex shapes with inside of a modelling environment. Since pov
has no direct nurb manipulation capabilities, and it is not a modeller, it
is just as easy to represent the final modelled shape with simple triangles.
There is no real difference in the final raytraced image no matter which
method is used and there would be a large overhead to adding nurbs support
to Povray.
I am not well informed where nurbs are concerned and what I have said may
be wrong.
--
Ken Tyler
See my 850+ Povray and 3D Rendering and Raytracing Links at:
http://home.pacbell.net/tylereng/index.html
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Ken wrote:
> Felix Petriconi wrote:
> > Are there other tools or programs wich support the possibility to export
> > bicubic patches into PovRay format?
>
> SPatch is the preferred utility of many people and is highly capable.
> http://www.cableone.net/alyson/spatch.html
Thanks for the information!
> [..]
> I think one of the main advantages with nurbs is that the format is good for
> modelling complex shapes with inside of a modelling environment. Since pov
> has no direct nurb manipulation capabilities, and it is not a modeller, it
> is just as easy to represent the final modelled shape with simple triangles.
> There is no real difference in the final raytraced image no matter which
> method is used and there would be a large overhead to adding nurbs support
> to Povray.
Yes, the representation might be easyer with triangles, but the files with the
triangles might be a little bit bigger than the nurbs description. Once I
created
a TIE fighter with Rhino. The size was about 12 MB. The PovRay meshfile
was about 125 MB and it took some time to parse it. (I know that there is
a utility by Chris Colefax which reduces the number of triangles.)
Greetings Felix
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Felix Petriconi wrote:
> Yes, the representation might be easyer with triangles, but the files with the
> triangles might be a little bit bigger than the nurbs description. Once I
> created
> a TIE fighter with Rhino. The size was about 12 MB. The PovRay meshfile
> was about 125 MB and it took some time to parse it. (I know that there is
> a utility by Chris Colefax which reduces the number of triangles.)
>
> Greetings Felix
One thing I have heard other Rhino users mention is that when exporting
the file to pov format they first do a triangle count reduction. If you
use smooth triangles in Pov you don't need nearly the number of triangles
you would need to see a smooth surface anyway. You can probably reduce
your triangle count considerably and still have a good looking model.
--
Ken Tyler
See my 850+ Povray and 3D Rendering and Raytracing Links at:
http://home.pacbell.net/tylereng/index.html
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Felix Petriconi wrote:
> Once I created
> a TIE fighter with Rhino. The size was about 12 MB. The PovRay meshfile
> was about 125 MB and it took some time to parse it. (I know that there is
> a utility by Chris Colefax which reduces the number of triangles.)
>
> Greetings Felix
Felix, in order to use Rhino with POVRay I'd suggest to export from
Rhino to 3DS format, then use 3DS2POV converter to create files with
mesh2 format, which will be much more compact and will retain UV mapping
information. In order to use mesh2 format, you have to use either
Superpath or UV patched POVRay.
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All I have to say is I paid $200 for Hash animation Master and wrote a plugin
for it that can export POV-Ray bicubic patches. Simple and easy. :)
One thing I've noticed is that NURBS appears to have been a fad. They can
accurately represent some objects that bezier patches cannot, yet from an
artistic point of view there is no real advantage. The latest thing is
subdivsion surfaces; NURBS are yesterday's news (if you buy into that malarchy)
-Mike
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> What are the advantages of NURBS (or should I say NURBSes?) over
> bicubic pathces?
Wha....? I thought bicubic patches *were* a specific subset of NURBs?
General NURB support, therefore, would be more flexible, by doing
anything a patch can do but being more adaptable? Wouldn't it? Okay,
If I'm wrong, blame it on being tired. I shouldn't be allowed near
a keyboard when I'm tired.
As to the matter of smaller file size... yeah, guess so, although I'd
be more concerned with render-time memory savings than stored file
sizes. Bezier patches, if I remember rightly, have (or at least had?)
an option to choose between patch types that preprocessed to triangles
or on-the-fly control point calculations. This traded off memory size
for computation speed depending on your needs. I imagine if
generalized NURBs were implemented, it would have similar options.
Nowadays, with faster processors, computations speed would probably
be less of a concern than available memory with huge models. Could
be nice in that case.
Charles
--
http://www.enter.net/~cfusner
"...Then darkness took me, and I strayed out of thought and time,
and I wandered far on roads that I will not tell..."
-The Two Towers, JRR Tolkien
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> Wha....? I thought bicubic patches *were* a specific subset of NURBs?
> General NURB support, therefore, would be more flexible, by doing
Sorry, I just want to clear up one thing. NURBS is not plural for NURB.
NURBS is the acronym for Non-Uniform Rational B-Spline. The correct
pluralization is NURBSs, no matter how ulgy it sounds.
--
Anthony L. Bennett
http://welcome.to/TonyB
Non nova, sed nove.
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Felix Petriconi <fel### [at] ruhr-uni-bochum de> wrote:
: (I know that there is
: a utility by Chris Colefax which reduces the number of triangles.)
If you are talking about the triangle mesh compressor, two points:
1) It doesn't reduce the number of triangles, it just stores them in a
more compact format.
2) The macro by Chris just reads the compressed data into povray (and
creates the mesh), it doesn't generate it.
--
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/
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Vahur Krouverk <vah### [at] fvaetecee> wrote:
: Seems like this subject will be good candidate for
: FAQ (or VFAQ, how about it, Warp?).
I can add it if someone gives me a question and an answer (which should be
comprehensive and correct).
--
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/
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Well, it depends what you're doing.
The main advantage I find in using NURBSs is adaptive generation and
degradation of the final rendered mesh and also vastly more modelling
methods compared to patches. A good example of the AG/D of NURBSs is when
using really complex models. If you render the model based on mesh patches
you could end up with a massive amount of triangles. With NURBS models you
can simply set the restraint angles and distances so it adaptively generates
the surface.
The other thing as I mentioned was the flexibility of modelling. For
example with NURBSs it's very easy to just trim up and blend two surfaces
together seemlessly.
This issue has come up a few times in regard to POV-Ray and it seems there
is the same problem. POV-Ray isn't a modeller, and modellers are needed to
make NURBS surfaces. Making up the keyword description for POV-Ray would be
near impossible considering the number of specialised surface triming and
blend functions along with all the point and CV splines. I personally have
no idea how it would be possible to make a tokinised description for NURBSs.
Someone also mentioned subdivision surfaces. This has become an offshoot of
NURBS modelling and uses a method called "soft selections" (the term changes
from modeller to modeller). Basically it works the same way only it allows
you to add weights to all NURBS points (even if it's a CV spline). While
NURBSs already support this, subdivision surfaces do it differently because
they work on existing models (they "subdivide" <- thus the name; the
surface).
Anyway, I think I said this the last time the NURBS issue came up: NURBSs
would be near impossible to impliment into POV-Ray and considering the
computational and programming overheads, it really isn't worth it.
Anyway, back to work, just thought I'd stop in.
--
Lance.
---
For the latest 3D Studio MAX plug-ins, images and much more, go to:
The Zone - http://come.to/the.zone
For a totally different experience, visit my Chroma Key Website:
Colorblind - http://listen.to/colorblind
Nieminen Juha wrote in message <37c3e249@news.povray.org>...
> What are the advantages of NURBS (or should I say NURBSes?) over bicubic
>pathces?
>
>--
>main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
>):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/
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