problems while loading very large STEP files - Forum Open Cascade Technology

Boqing Dong
Tue, 09/16/2025 - 05:33

Forums:

Data Exchange and Application Framework

I had very large a STEP file(64MB) to be loaded to a TopoDS shape and the loading took more than 6 hours.

Anything I can do to improve it?

The code I used:

Dmitrii Pasukhin
Tue, 09/16/2025 - 15:10

64mb is not big. 700mb takes about 3-5min usually.

OCCT have a issue when your model is kinda created from planar polygons (thousands of faces inside shell). In that case it will takes a lot time. Is it your case? If yes - i can suggest a workaround while we are preparing fix (will takes a few months). Or if it is not your case - then we need to have a file from your to analyze.

Also, please share the OCCT version used for your import process.

Best regards, Dmitrii.

Boqing Dong
Wed, 09/17/2025 - 03:24

Thank you for the elaboration.

I'm not sure which case it is, as the file was from a client who is not likely to know it either.
Could you please help analyse the file attached?

Also, the OCCT version is 7.9.1.

Best regards, Boqing

Attachments:

error_64m.rar

Dmitrii Pasukhin
Wed, 09/17/2025 - 17:56

Yes, it is a case, when model have thousands faces inside single close shell. Please apply parameters from that thread and disable the healing of order of faces inside shell.

Link: STeP Importer stuck and hogging memory - Forum Open Cascade Technology

Best regards, Dmitrii.

Boqing Dong
Thu, 09/18/2025 - 04:27

Hi Dmitrii,

Thank you for identifying the problem!

I read the thread you mentioned.

It's a bit long and has something I don't quite understand.

So I write down my thoughts here. Please correct me if I get anything wrong.

The loading problem is caused by OCCT trying "FixShellOrientationMode", so I think I should disable it as a workaround.

Since 7.9.0, the shape healing parameters are available in DE Interface. So I changed my code like this:

However, it seems not to work. The loading is still stuck at "TransferRoots()".

Did I miss anything import here?

Best regards, Boqing

Dmitrii Pasukhin
Thu, 09/18/2025 - 11:09

It looks as valid usage. I need to check locally, my apologies. Will check during current week.

Best regards, dmitrii.

Boqing Dong
Wed, 09/24/2025 - 05:42

Hello Dmitrii,

Any news about the problem?

Best regards,
Boqing

Dmitrii Pasukhin
Wed, 09/24/2025 - 18:41

Hello. Your file have another issue, resolving of which is not done and not yet prioritized.

As for an old issue with stack with huge number of faces per shell - it is waiting for integration now, fixed:Shape Healing - Optimize FixFaceOrientation

As for your fix, could you please create a GH issue with file attached? If issue is critical for you and need to be solved in some near time, please reference to "Bug fixing and correction" commercial request: Custom Software Development & Services - OCCT3D

Best regards, Dmitrii.