Importing DWG CAD files into Houdini?

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Hey Guys,

Has anyone imported DWG files into Houdini for CAD contracts? Can houdini do this natively or do you have to do a work around like load them into Rhino then save out to IGES and them import them as NURBS or can it be done with polytrans?

Cheers,
Nate Nesler
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polytrans doesn't work.
another “workaround” is using 3Dmax
Michael Fuchs TD CAMF Productions Ges.m.b.H. Austria

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All cad packages that support the output of .dwg files can also output .dxf files. Ask for .dxf files.

I have AutoCAD 2004 and I load in .dxf files in to Houdini. You will get all the line work but none of the text (unless converted to lines) or the special spline curves. The layers in AutoCAD come in to Houdini as groups by default. This is more for Architectural work.

If there are more complicated surfaces, you will have to go the 3d Max route as Michael has recommended.

In my experience it is hard to get the CAD users to give you customized output data.
There's at least one school like the old school!
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Hey Guys,

In that case I will go to Rhino, then to XSI or PolyTrans. Rhino can save DWG files to XSI file format with Nurbs Curves. It might do it for Houdini too I don't know. I am not buying max I have used it in architecture contracts before and it does just take the files right in but thats alot of extra money for just one feature I need, and I would not use the package for anything else. Rhino is cheaper and more useful to me. Thanks for the info about PolyTrans I have never used that package.

Cheers,
Nate Nesler
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Nate, use Rhino and export IGES from it.
Import to huudini.
You are done

Cheers Peter

If you work with acad and plan to export data for further modeling it's convenient to draw very precisely, not to have lines you don't know about or or useless rubbish and use closed polylines. It makes life easier in later production.
You import it anywhere and work directly on acad curves.
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Hey Peter,

Do you have a link to this ACAD program. I prefer NURBS because then I can switch to polys at any time I want, but I have noticed that houdini renders much faster with NURBS. Its is blazing fast on mantra with NURBS, and Houdini has really strong NURBS tools. So I have several reasons for using NURBS Curves. I don't make the autocad files they are given to me from clients that want a visualization. So I generally don't mess with their CAD files that they submit to me.

Cheers,
Nate Nesler

P.S. Thanks for the Info
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Hi Nate, by ACAD I actually meant Autocad sorry, just a shortcut me and my friends use.
Acad is expensive and when you don't use it all the time it's absolutely not a profitable investment.
Rhino is very good in reading .dwg. You should be given dwg's from autocad 2000 (maybe 2004) because this is the last format it accepts (apart from earlier ofcourse).
It displays almost unchanged dwg file, every line, polyline etc.
Rhino is also not so expensive and it is a fabulous modeler.
If you need a CAD software for modifying/cleaning client's files (which you are very likely having to clean) you can search for some cheap autocad like drawing software, I know there exist a few but I can't help you with names.


I didn't know houdini renders nurbs faster? Doesn't mantra convert them to polys anyway?

cheers

Peter
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I am interested to hear how you go with this because I am in the visualization game too and at work I use 3d studio vis. I could buy my own select / escape version for my self sooner if I knew I could use it for my major earner. Importing DWGs is the major issue and one or two things about the snapping tools could make my life better but the rest is fantastic. Exporting DWGs would be nice too but not to important. With the SDK free all it would take is a C++ guru to make a plug-in or something. But I don?ft happen to be or know one of them, there may be some licensing issues but I am just guessing.
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I take it from all of you that .dxf isn't going to do it?
It is real easy to export .dxf from AutoCAD2004 and it comes in to Houdini just fine. Groups for layers.
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Hey,

Correct me if I am wrong but DXF is not a format that supports NURBS. Quite frankly I lose alot of information in the .dxf format gerenally. Actually I am a C++ Guru but I don't know how much time I would have to code that plugin and how involved it would get. I would just have to learn HDK which probably would not be too bad for me considering I already know Maya's SDK. The things I would really want to see with an import of a CAD file is the units and elivations preserved and for all of the curves to be NURBS when the import is done. I have not seen this happen correctly yet with DXF plus I tend to see alot of errors in DXF format. I prefer OBJ over DXF any day. The best solution I agree would to be to have a DWG import plugin into houdini that even does some of the building for you in an auto modeling system. I have already thought of this to some extent but I don't know again how involved this would be. The smart thing would be to build components of the building in parts that would be OTLs that would read in base parts objects as a library type function system that would allow you quickly and rapidly prototype a building and build new parts of the components of the building to add to the library. I am not explaining this well but it makes alot of sense in my head. lol Basically a window would be a component of the building and a piece of the frame would be a part to the component and you would look up that part from a library of window frame parts as a funtion in the OTL straight from the hard drive. Anyhow thats probably how I would do it.

Cheers,
Nate Nesler
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Hey Peter,

I know OpenGL converts NURBS to Polygons do to hardware limitiations if I render right. I might not remember right. I don't know if NURBS are converted to Polygons from a software render. That could be totally different. I just noticed that if I took a Polygon surface and select for the object to polys to be rendered as subdivision surfaces I get like a render time of say 2 minutes on a large poly sufrace. Then if I convert it to NURBS and got something like 2 seconds. I mean it was a huge difference. I also tested some other NURBS surfaces and got simular results. So yeah I think the NURBS in houdini are faster in my experience. I don't know why that is though which I hate not knowing why something is because then there is always room for error.

Cheers,
Nate Nesler
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Are there any standalone cad importers for houdini? I could do with dwg, and jt, skp would be a massive bonus too as many of the architects supply me with those files.

Trying to make Houdini my only tool for archviz
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Hi, for conversion is best opensource software g3CAD3D, i try it now integrate to houdini any conversion igs to stl. Maybe anybody help with this tool. Link is here: http://www.gcad3d.org [www.gcad3d.org]
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