IGES-STEP export

Recently I experimented a lot with export to IGES and STEP in OCC, with the purpose to import a geometry into another CAD software like f.e. Solidworks, CATIAV5R16 and some gird-generation tools such as gambit. However, I found the surprising result that each program represents the OCC geometry in a different way, or even sometimes fails to open it. I personally believe that this is not due to the STEP and IGES writer of OCC but more to the different interpretations of STEP and IGES by all softwares. I found for instance that the STEP reader of CATIA performs quite poor, while the one of solidworks does a better job on OCC STEP-IGES files. But this is not a general rule, sometimes it's the opposite, for instance STEP geometries that I receive from other persons are as a rule best opened by CATIA. I wonder if other people have the same experiences as I have. I would like to know what other people's experiences are when it comes down to import and export form and to any software. Also I would like to know if there are some "best practices" in order to export a STEP and IGES from OCC. For instance you can specify the tolerance in the STEPControl_Writer (STEPControl_Writer::SetTolerance();) but I did not see any improvement by that.
Thanks in advance,


Pawel's picture

Hi Tom,

import/export of gemetrical data is problematic. In my opinion it is better to use STEP. IGES is often ambiguous. However, some CAD/CAM systems offer various import/export options (like the art or tolerance of imported entities) - maybe you could try those. Additionally, something like geometry healing in CAD/CAM sytems (you will find it also in OC) is usually implemented.

Hopefully, this little experience with import of STEP/IGES will help.

Best regards

verstrae's picture

Thank you Pawel for your reply. I use as well shape healing in OCC before exporting. But I wonder if one can specify some other STEP specific information on presision and tolerance rather than in the CAD software that opens them. However, I think you are right when saying that import/export is problematic. STEP in my opinion could not achieve the goal it was designed for, that is to be the universal datatype for exchange...