IGS/STEP Surface to Solid Body Conversion


I am getting an IGS/STEP file exported from Tekla Structural Software from a customer and was wondering if Rhino can convert the surface data into a Solid Body that can then be exported to Solidworks?

Thank you.

Hi Dakotabird- Step should come in solid if it was exported as solid; Iges imported stuff, assuming all the surfaces are in place to form a solid and edges are clean and within tolerance, will form a solid if you Join the surfaces. Export as STEP for SolidWorks, or export as Rhino V4.


Ok so the .igs file I import is just all lines no solid bodies. If I export this to .stp and import into solidworks it creates surfaces but not of the desired effect. Basically the .igs file contains tubes and when I export the .igs file to .stp and import it creates faceted surfaces instead of smooth round tubes. I was wondering if it is possible to export the .igs file to a format that where it converts those lines into round smooth tubes instead of the faceted ones. So far I have had no luck with other conversions softwares or solidworks import options. Is there an option to add my file anywhere here to show you what I am talking about?

Can you please post an example file? (smaller the better).


Yes how do I attach a file to the post?

Click on this button in the top of the message box:


Model.igs (1.7 MB)

Ok this is the .igs file

Hmm- pretty strange model- it looks like it has been converted from a mesh model- so there is no way you can get round tubes here unless you make your own using these as reference. The individual surfaces are bad- the trim curves are not within the surface domain- I’ll have to check to see if this is our fault or just odd formatting of the iges file- there are planes defined but only one unit square, plus a much larger trim curve.

At any rate you an improve things by:

DupBorder (this will get you the correct trim curves)
SelClosedCurves (will get those borders)
PlanarSrf (makes nre planes trimmed by those curves)


Ok I followed those steps and tried exporting as both a STEP and an IGS using the Solidworks Solid option and both import into solidworks but are empty(no parts).

Notice I said ‘improve’ and not ‘fix’. You still need to Join all the new planar faces and you may need to add some to close off the ends of the tubes and Join those to make solids… Then Export to STEP or Rhino V4 to open in SolidWorks. Any luck at all?

Apologies, I am not familiar with the software yet so give me some time to learn the operations and I will get back to you. I see what you mean by open faces. I will attempt to repair those.

Always keep in mind…garbage-in = garbage-out, though you have been given a strategy to try and produce less garbage out. However, the best approach is via the source if possible, assuming you have any control/sway/empathy over that from the file originator…

We get the files from a user that is modeling in Tekla so there must be an issue with their export. I am currently working on getting a license for Tekla Structures to test export options in their software. I definitely see the garbage in now that you point it out.

Good move! What you are doing gives you considerable control over the process. Get the native file and play. In future you will be able to say…do this, that, and the other. More importantly, you will learn whether the whole endeavor is possible under the right circumstance, or an exercise in futility. My guess is that you are going get it figured. Good luck!


You could ask if Tekla has CIS/2 exporting.
As you are exporting steel structures, RhinoBIM maybe of help.
You may need to do some profile mapping.


They do. They also have STEP exporting but it exports as a STEP AP230 not AP203 or 214. Is AP230 useable in Rhino? I tried and it attempts to join surfaces but eventually no geometry is created.

@chuck , do we, or should we, import any STEP other than 203 and 214?


Did you have a go importing the CIS/2 file.
You’ll need to download the RhinoBIM plugin.

I’m not sure what’s in AP230 that isn’t in 214. I’ll check when I can, in the next week or so. Anything in a 230 file that is supported by 214 should import.

Can we see the STEP file?