CATIA generates STL file

[therockyy]

Dear all,

My friend sent me a CAD file created in CATIA. I use CATIA generated the STL file and imported it into another software, but the geometry seems wrong.

I tried to generated an IGS file in CATIA and imported it into Pro/Engineering to generated a STL file. The two STL files generated by CATIA and Pro/E are totally different.

It seems the CAD file created by CATIA mainly consists of curves rather than solid objects. Therefore, when Pro/E imported the file into STL format, only those solid objects are retained.

I never used CATIA before, can someone explain why the stl files generated by CATIA and Pro/E are so different?

For some reason, I cannot upload the file. Please check the http://db.tt/cPrjiwE and download it. It contains the CATIApart file, and two STL files named "complete with feeds modified.stl" and "complete_with_feeds_modified.stl" generated by CATIA and Pro/E respectively.

Thanks a lot!!!

Jason

 

[MrCATIA]

Jason, a couple comments on your post.

You might want to import the STL file back into CATIA and compare it to the original file to verify if the STL file is good or not.

Using IGES to exchange the file to Pro-E is not the best, since IGES typically only passes surface geometry. This could explain why the data looks different in Pro-E, and why the STL files are so different. Try using STEP instead, if you want to exchange solid files.

 

[therockyy]

Jason, a couple comments on your post.

You might want to import the STL file back into CATIA and compare it to the original file to verify if the STL file is good or not.

Using IGES to exchange the file to Pro-E is not the best, since IGES typically only passes surface geometry. This could explain why the data looks different in Pro-E, and why the STL files are so different. Try using STEP instead, if you want to exchange solid files.

Thanks for your reply. I did as you said, import the STEP file into Pro/E and import STL file back into CATIA. Both the geometries look fine. The problem I'm encountering is the geometry cannot be recognized correctly in the CFD software and the reason for that is the CATIApart model has some problem. I checked the CATIApart file. It seems the file only contains faces and surfaces, which give a perfect surface geometry but no solid information. This has been confirmed by slicing the geometry. The cross-section of the geometry shows a shell and nothing inside the shell. This is different from other solid CAD file I imported before.

So, the problem seems changed to how to create solid objects from the CATIA part file which only has curves, faces and surfaces. Is that possible to do that in CATIA?

Thanks!

Jason

 

[MrCATIA]

Yes, you can create a solid from the surface geometry. But it's not easy, especially for someone who has never used CATIA before.

The easiest and quickest solution is to contact your friend and have him send you the solid version of the part.

 

[Kevin De Smet]

Important to note: STL is not an "absolute" file type. Allow me to elaborate on that a little bit.

IGES or STEP stores the model in its entirety and there are a few options here and there, but generally it's an "absolute" thing like 1+1 = 2 there is only one answer to any particular model or file. Whereas STL subdivides the model up into a finite numbers of triangles, and you can control how fine or coarse the STL file of the model will be.

So depending on the settings of the STL exporters in various programs (and most allow you to change these manually) you will indeed get different resulting models from using the STL filetype.