Hallo,

are there any plans to include NURBS into PovRay?

I think it would be a great advantage to have NURBS in PovRay because
You would not have to handle big meshes.

I know it is not so easy to implement this feature because it is
mathematicaly
a little bit tricky. But I believe that the time consuming ray-testing
AND reading
of big meshes would be history with this feature.

(I have worked with BMRT, which supports the NURBS, and it was really
nice
to render quite complicated modells.)
By the way, some of the great modellers (like Rhino) support NURBS.


I just wanted to start a discussion. Perhaps there are some good reasons
not
to include NURBS into PovRay.

Greetings,

Felix

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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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Hi all!

Funny you should mention this.  I've been working on molding a 3Com Ethernet
card as closely as possible.  The first images are posted in the p.b.i.
group.  Everything is being modeled using Rhino, piece by piece, positioned
and textured in Moray, then finally rendered in POV-Ray.  The only things I
have done so far are the board, bracket, all screws, activity LED, the
complete AUI connector, and the AUI connector lock.  I still have to do the
Twisted Pair connector and board components as well as the board traces and
writing.  (The last two I don't have any idea how I'm going to do yet!)

Anyway, I guess it would be a good thing to include NURBS support (although
it would probably cause the POV-Team to start charging for POV-Ray!)
Currently the pieces are exported to Moray using Moray's UDO/INC.  This
generates mesh files of pretty considerable size and complexity.  All
objects currently total about 49MB.  Guess which piece generated to biggest
file (by far!).  Like I said, I still have alot of work to do and I estimate
that the total size is going to be around 125MB in exported files.

The stats on the POV rendered models so far include:

    640 x 480, Alias 1 adaptive, No Radiosity
    Peak memory used:  38MB
    Time to parse:   0h 13m
    Time to trace:    2h 38m


Felix Petriconi <fel### [at] ruhr-uni-bochumde> wrote in message
news:37C3EE28.C51EB041@ruhr-uni-bochum.de...
> Hallo,
>
> are there any plans to include NURBS into PovRay?
>
> I think it would be a great advantage to have NURBS in PovRay because
> You would not have to handle big meshes.
>
> I know it is not so easy to implement this feature because it is
> mathematicaly
> a little bit tricky. But I believe that the time consuming ray-testing
> AND reading
> of big meshes would be history with this feature.
>
> (I have worked with BMRT, which supports the NURBS, and it was really
> nice
> to render quite complicated modells.)
> By the way, some of the great modellers (like Rhino) support NURBS.
>
>
> I just wanted to start a discussion. Perhaps there are some good reasons
> not
> to include NURBS into PovRay.
>
> Greetings,
>
> Felix
>

Post a reply to this message

Felix Petriconi wrote:
> 
> Hallo,
> 
> are there any plans to include NURBS into PovRay?
> 
> I think it would be a great advantage to have NURBS in PovRay because
> You would not have to handle big meshes.
> 
> I know it is not so easy to implement this feature because it is
> mathematicaly
> a little bit tricky. But I believe that the time consuming ray-testing
> AND reading
> of big meshes would be history with this feature.
> 
> (I have worked with BMRT, which supports the NURBS, and it was really
> nice
> to render quite complicated modells.)
> By the way, some of the great modellers (like Rhino) support NURBS.
> 
> I just wanted to start a discussion. Perhaps there are some good reasons
> not
> to include NURBS into PovRay.
> 
> Greetings,
> 
> Felix

Well, for discussion you can search this very same newsgroup for NURBS
in subject. There is at least 4 threads with quite smart names as "NURBS
support", "NURBS patch", "NURBS...", "NURBS?". This will give quite good
overview of opinions. Seems like this subject will be good candidate for
FAQ (or VFAQ, how about it, Warp?).

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Hi again,

Nieminen Juha wrote:

> What are the advantages of NURBS (or should I say NURBSes?) over bicubic
pathces?

I did not know that there are bicubic patches. I read then the documentation
of the current
PovRay version. There is mentioned:

"Like triangles, the bicubic patch is not meant to be generated by hand. These
shapes should be created by a special utility. You may be able to acquire
utilities to generate these shapes from the same source from which you
obtained POV-Ray."

My next step was to search for such a utility on the PovRay homepage. I just
found the program
breeze designer, which seems that there is no further development since 1996.

Are there other tools or programs wich support the possibility to export
bicubic patches into
PovRay format?

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 argumentation, but it supports a little bit that NURBS have
advantages against bicubic patches.

Greetings, Felix

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BTW, Felix, your computer's timezone seems to be wrong by one hour
(shouldn't it be +2000 for Germany??). Juha's response is before your
question!

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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

Post a reply to this message

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

Post a reply to this message

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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