Hello,

I am new to povray and trying to import an .iv file to povray. Here I
encountered a problem with the texture coords. Simply said: they get lost.
I googled around and found a page saying that povray does not support
texture-coords yet. Is this claim correct, and if it is, is that going to
change in the near future?

Thanks in advance,
Bo

ps: english is not my native language, so my excuses for bad grammer.

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"Bo" <nomail@nomail> wrote:
> Hello,
>
> I am new to povray and trying to import an .iv file to povray. Here I
> encountered a problem with the texture coords. Simply said: they get lost.
> I googled around and found a page saying that povray does not support
> texture-coords yet. Is this claim correct, and if it is, is that going to
> change in the near future?
>
> Thanks in advance,
> Bo
>
> ps: english is not my native language, so my excuses for bad grammer.

Well, i've never heard of *.iv files and google couldn't help me with that
in a rush. In addition i don't know how you "imported" them to POVRay
whereas the texture coordinates get lost (how can POVRay import files?).
Maybe this is a typo and you meant *.uv files (but i never heard of those
either) but from what you wrote i guess you mean uv mapping as it is called
in POVRay and that is supported very well! Maybe you want to look up
"2.5.7 UV Mapping" in the docs.

Hope that helpes
Regards Roman

ps: english isn't my native language either and i'm not the only one in this
forum. i was told there's no need to apologize for poor grammar :D

Post a reply to this message

"Roman Reiner" <lim### [at] gmxde> wrote in message 
news:web.440d82954a82760947d10e600@news.povray.org...
> "Bo" <nomail@nomail> wrote:
>> Hello,
>>
>> I am new to povray and trying to import an .iv file to povray. Here I
>> encountered a problem with the texture coords. Simply said: they get 
>> lost.
>> I googled around and found a page saying that povray does not support
>> texture-coords yet. Is this claim correct, and if it is, is that going to
>> change in the near future?
>>
>> Thanks in advance,
>> Bo
>>
>> ps: english is not my native language, so my excuses for bad grammer.
>
> Well, i've never heard of *.iv files and google couldn't help me with that
> in a rush. In addition i don't know how you "imported" them to POVRay
> whereas the texture coordinates get lost (how can POVRay import files?).
> Maybe this is a typo and you meant *.uv files (but i never heard of those
> either) but from what you wrote i guess you mean uv mapping as it is 
> called
> in POVRay and that is supported very well! Maybe you want to look up
> "2.5.7 UV Mapping" in the docs.
>
> Hope that helpes
> Regards Roman
>
> ps: english isn't my native language either and i'm not the only one in 
> this
> forum. i was told there's no need to apologize for poor grammar :D
>
>

Hi Bo,

I also did a google search and eventually came up with .iv files being the 
format used by Inventor, which has since been superceded by OpenInventor 
(which uses the same format). I've seen some references that imply that this 
is related to 3D Scanning technology?

I would guess that by 'Import' you mean you've converted some .iv files into 
a format that POV-Ray can use. The web site at 
http://www.csit.fsu.edu/~burkardt/data/iv/iv.html describes a number of 
converters. What converter have you used and what is the format of the 
output you ended up with (e.g. mesh, mesh2)?

I found a definition of Inventor texture coordinate mapping at 
http://vsvr.medien.fh-duesseldorf.de/~herder/tech/OpenInventor/Workshop/Texture/texture-edit.html,

but this seems to describe a few alternative mechanisms for mapping textures 
to surfaces and I'm not sure which method you are interested in emulating in 
POV-Ray. From quickly looking through the examples on that web page it 
doesn't seem to be doing anything much that POV-Ray can't do. It just seems 
to be scaling, translating and rotating image maps.

POV-Ray can scale, translate, rotate and warp image maps as well as 
providing alternative map types such as spherical and cylindrical,

Are you able to describe more fully what it is you're having difficulty 
doing?

Regards,
Chris B.

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Hi there, thanks for your time.

Okay, you are right. By saying "import" I meant that I have converted a Open
Invetor File (.iv) to .pov using a converter named "ivtopov.exe". I did not
look more closely to it asuming that it works correct (maybe an error :) ).

So I have a CAD Software called VPack (www.erpa.de) using OI (Open Inventor)
libs to create .iv Files. Those images are to be printed with a fairly high
resolution on DinA3 formated pages. That is where pov-ray comes in.

But for now my textures, which are stored in uv-coords in the .iv-File (so
thats what I guess from overlooking sample files) are not being displayed
correctly. Maybe thats a problem with the converter. I will try IVCON on
that one.

I hope I explained it a little better this time.

Bo

Post a reply to this message

"Bo" <nomail@nomail> wrote in message 
news:web.4411376c4a827609ec325a890@news.povray.org...
> Hi there, thanks for your time.
>
> Okay, you are right. By saying "import" I meant that I have converted a 
> Open
> Invetor File (.iv) to .pov using a converter named "ivtopov.exe". I did 
> not
> look more closely to it asuming that it works correct (maybe an error 
> :) ).
>
> So I have a CAD Software called VPack (www.erpa.de) using OI (Open 
> Inventor)
> libs to create .iv Files. Those images are to be printed with a fairly 
> high
> resolution on DinA3 formated pages. That is where pov-ray comes in.
>
> But for now my textures, which are stored in uv-coords in the .iv-File (so
> thats what I guess from overlooking sample files) are not being displayed
> correctly. Maybe thats a problem with the converter. I will try IVCON on
> that one.
>
> I hope I explained it a little better this time.
>
> Bo
>


Hi Bo,

The good news is that, from what I've just read, what you are attempting 
seems to be possible.

POV-Ray 3.6 (and possibly earlier versions) supports UV mapping of textures 
onto mesh objects. See section 3.5.7 UV Mapping of the docs where there's an 
example of the syntax. You could take a look inside the output from 
'ivtopov' to see whether it specifies a mesh or mesh2 with uv mapping and to 
check whether it's specifying the syntax correctly. POV-Ray supports quite a 
few formats - See Bitmap-Type in section 3.5.1.5.1  "Specifying an Image 
Map" of the POV-Ray documentation.

You also need to check the file generated by the converter to see how the 
texture is specified. I suspect it might be an RGB image in a separate file. 
If it is you could open it in a graphics editor to check that it contains 
the texture you think it should contain. Also make sure it is in a format 
that POV-Ray understands and obviously check the POV-Ray message stream to 
make sure it's not complaining about anything to do with the file.

I found a reference at 
http://www.hammerve.com/NewHome/FreeStuff/Converters/iv2pov.c++ to iv2pov (a 
google of 'ivtopov' came up empty).
I notice they say "The mapping between Inventor's texture scheme (UV 
mapping) and POV 3.0's is (at best) an estimate - don't expect a perfect 
fit.". They also say " By the way - it does not convert any .rgb files used 
by textures into the .tga format POV wants - you have to do that by hand.".

If I had to guess, I'd say that the converters you are using are generating 
a texture file as a bitmap and that the texture specification in the output 
file isn't being set correctly.

If you can't spot the problems I would suggest cutting and pasting a few 
lines of the mesh definition and a couple of lines showing the texture 
definition into a posting here to see whether anyone can spot the problem.

Hope this helps.
Regards,
Chris B.

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