export for houdini

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crouspix
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export for houdini

Post by crouspix » Wed Nov 28, 2007 10:59 pm

hello all

Is there a way to run indigo with Houdini 9?

There will be exported to houdini 9 in the futur?


Thanks

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Kram1032
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Post by Kram1032 » Thu Nov 29, 2007 5:15 am

Any of the exporters is written by people, who use the app.
So, if you want your exporter, you'll need to either write it yourself or ask other Houdini-users to do so ;)

About the using: can it export obj? Then, you could, for example, import your houdini scene to Blender, tweak the materials and settings with Blendigo and finally export to Indigo ;)

crouspix
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Post by crouspix » Thu Nov 29, 2007 10:18 pm

I did not think. It is a good idea as long as the scenes are simple. Blender is free. Yes why not.

I learning Houdini 9, amazing, simple to use, verry nice......I do not know a lot of people on houdini. I will seek a programmer :wink:

Thanks

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Kram1032
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Post by Kram1032 » Fri Nov 30, 2007 8:47 am

no problem ;)
For 'till then, feel free to ask questions about blender :)

jiversen
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Post by jiversen » Tue Jan 29, 2008 11:05 am

I started this last Sunday night to write an H9 exporter, so hopefully in the next couple of weeks I'll be able to get a test version out there.

I might be delayed a bit because I'm moving house on Friday and I have to do a lot of crazy house work - but hopefully not too much down-time.

I got the camera, mesh and model entities going to Indigo already, with just a couple of questions which I should be asking the developers. I am a TOTAL noob at Indigo, I have no real idea about some things.. is this is the best forum to ask technical questions?

Things like:
*/ Is there an alternate way of specifying transforms for models? The euler position and 3x3 rotation matrix could just be a 4x4 matrix instead.
*/ I'm confused by the fact that I have to fully specify every tag in the <camera> block - when the Indigo manual clearly states their default values. Surely if they have defaults, I should be able to skip those tags?
*/ How do I deactivate DOF rendering?
*/ Looking through examples and docs I see no support for motion blur of any kind. Is this correct?

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dougal2
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Post by dougal2 » Tue Jan 29, 2008 11:51 am

1. all of indigo's rotations are 3x3 matrices, and that's the only supported format.
2. You can only skip tags that are explicitly marked as optional. The slight exception to this rule is that you can override the inifile.txt settings in the render_settings tag, you can leave out any value given in inifile.txt to use defaults.
3. You can't really. That's like asking how to deactivate DOF on a real camera. You just have to use suitable settings to reduce the effect.
4. There is no motion blur at all.

I don't know what language or API you've got available in Houdini, but it might be worth looking at the source of the other exporters (where available, some are binary) if you need pointers.

Good luck!

jiversen
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Post by jiversen » Tue Jan 29, 2008 12:43 pm

Hi Dougal,

Thanks for the useful info; it's great to know these answers (even though they all just confirmed my fears :wink: ).

The exporter is written all in Python (the Houdini python API is called SOHO (for export) and HOM (general purpose)). It would be great to look at any other python exporter, and/or the source code for the "complete" exporter in any language. Can you make any suggestions for these?

Thanks,
Jason

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dougal2
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Post by dougal2 » Tue Jan 29, 2008 12:50 pm

The only one in python is the Blender exporter.
I'm not a blender user though, so I've had no need to look at the source or even learn python.

I've done work on the Maya exporter, which is in Maya-specific MEL script.

AFAIK, the other main exporters (Max and C4D) are binaries, with source not available.

jiversen
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Post by jiversen » Tue Jan 29, 2008 2:08 pm

Thanks for the pointers. I appreciate the help.

I'll get whatever I can out by Wednesday - and I'll probably journal my progress in another thread on odforce.net (to which I'll post a link here later) and also periodically write in here.

jiversen
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Post by jiversen » Tue Jan 29, 2008 4:28 pm

So I see that all scales on models have to be Uniform Scales too; is there a workaround for this to have non-uniform scales at all? It seems like this might hinder instancing quite a bit, especially if you're reluctant to bake non-uniform scaling into the mesh definition. Any ideas?

EDIT:

Ah ok; unexpected bonus solved my situation. It turns out that if your 3x3 rotation::matrix tag has scales in it, it'll use those and you can just set <scale>1</>. So luckily it's not just rotations it cares about in the rotation tag.

jiversen
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Post by jiversen » Wed Jan 30, 2008 6:20 am

For those interested in how this exporter develops, here is a link:
http://forums.odforce.net/index.php?showtopic=6405

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dougal2
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Post by dougal2 » Wed Jan 30, 2008 6:43 am

Just read your first post there.


It might help you to know that Indigo will directly read .OBJ and .PLY objects too.

The way I export for Maya is to use Maya's built in OBJ exporter and reference the saved files in the XML. It's very fast, saved a lot of time in developing the exporter and keeps the XML scene filesize down.

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Zom-B
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Post by Zom-B » Wed Jan 30, 2008 6:51 am

Its nice to see having Houdini users access to Indigo soon :)
I look forward to a new fresh breeze of Pictures!

Thanks a lot for your work jiversen!
polygonmanufaktur.de

jiversen
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Post by jiversen » Wed Jan 30, 2008 7:51 am

dougal2 wrote: It might help you to know that Indigo will directly read .OBJ and .PLY objects too.

The way I export for Maya is to use Maya's built in OBJ exporter and reference the saved files in the XML. It's very fast, saved a lot of time in developing the exporter and keeps the XML scene filesize down.
That is good to know - thanks - I thought it was only .3ds for some reason. I assume the connectivity still has to be triangles, right?

I already have the triangles being spewed out into XML already - but I'll be sure to support external archives in the regular Houdini manner in the future.

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dougal2
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Post by dougal2 » Wed Jan 30, 2008 9:42 am

Triangles are your safest option, but I think some n-gons will also work - be careful with normals and how the polys are modelled in particular.

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