3D Interoperability

[traceparts]

Hello,

We have to interface our application with CATIA. So, to do this, we use ACIS/STEP translator (R16SP07) to create a STEP file and then, the end-user can import this STEP file in CATIA

Now, the problem is that CATIA seems to have a very limited support of STEP format (even in latest version of CATIA like R19SP05)

Indeed, with some STEP files, CATIA generates an error saying that some STEP entities (like TOROIDAL_SURFACE) are not supported!

This is really a big issue for us...

So, is it possible to tell the ACIS/STEP translator to only use some "basic" STEP entities rather than advanced ones?

Or can we simplify the ACIS model before using the STEP translator? (When I say "simplify", I mean only use simple/basic entities/elements to describe the geometry/topology)

FYI, I really don't have much skills in STEP format, so I'm just believing that there are some basics and advanced STEP entities, because this problem does not always occur, I mean, some STEP files are correctly imported in CATIA even if the models are complex....

Any help will be greatly appreciated.

Best regards,

Olivier.

[ejp]

olivier, i have lots of experience with step and catia v5 and i find it hard to believe the step translator is complaining about toroidal surfaces.  toroidal surfaces are well supported by every cad system i know of so i think there must be another problem.  if you want to send me the step file, i would be happy to look at and let you know if i can see a problem with it...

[traceparts]

Hello,

Thank you for your answer.

Yes, this sounds also strange for me, but the fact is that other CAD systems we tried (SW, Inventor, SE...) do not have any problem with these STEP files

I attached an example ("head.stp"). If you have CATIA V5, please open the STEP file in CATIA and then look at the generated "head.err" & "head.rpt" files:

My "head.err" file has the following content (sorry, this is in french, but errors mean "this basis surface is not supported"

!  <E> [0047] [T=TOROIDAL_SURFACE] [#58] Cette surface de base n'est pas prise en charge 
!! <E> [0002] [T=ADVANCED_FACE] [#47] Elément non créé 
!! <E> [0002] [T=ADVANCED_FACE] [#47] Elément non créé 
!  <E> [0047] [T=TOROIDAL_SURFACE] [#66] Cette surface de base n'est pas prise en charge 
!! <E> [0002] [T=ADVANCED_FACE] [#51] Elément non créé 
!! <E> [0002] [T=ADVANCED_FACE] [#51] Elément non créé 
   <W> [0904] La face #53 a été divisée en faces 2 CATIA V5
   <W> [0903] [T=CLOSED_SHELL] [#41] Erreurs détectées lors de la création de la surface ;  tentative de réparation 
   <I> [0776] [T=CLOSED_SHELL] [#41] Le nom de l'entité est CLOSED_SHELL #41
!! <E> [0002] [T=MANIFOLD_SOLID_BREP] [#24] Elément non créé

Best regards,

Olivier.

PS: We also found that if we export again the same model from SW, Inventor, SE and so on... to a new STEP file, this latter does not contain any toroidal_surface entity but some B-SPLINE entities. Then, CATIA can load this STEP file without any problem!

So, if we don't have any choice, we plan to use api_convert_to_spline () before exporting the model from ACIS to STEP file.

What do you think about this solution?

[ybiyani]

Hello traceparts,

What is the behavior with R20SP1? R16 SP7 is a very old version and on longer supported.

Regards,

Yogesh

[ejp]

olivier,

the problem is in the definition of the toroidal surface in the step file, the major radius is negative, this is illegal.  i suspect the torus definition in the originating format is degenerate (lemon or apple) and is not being mapped correctly to step.  this is clearly a problem in the spatial interop step translator...

by the way i have attached a log file from an independant viewer i use on occasion to validate step files.  as you can see, the problem entities are identified...

[traceparts]

Hello Yogesh,

At this time, for internal reasons like dependency with another 3rd-party library, we can't upgrade to the latest release of ACIS (even if we plan to do this ASAP)

Best regards,

Olivier.

[traceparts]

Hello Ed,

Thank you very much for the time spent on our problem.

So, you think this a problem inside the ACIS/STEP translator?

As I said it above, we can't upgrade to a more recent release of ACIS... so, do you have any idea to workaround or fix this problem?

(FYI, the original ACIS model was built with a sketch and a revolution operation applied to the sketch)

Best regards,

Olivier.

[ejp]

olivier,

the problem is definetly in the acis/step translator, i would report a bug to spatial...

i think the only option you have is to convert the analytic surfaces to splines while reading the acis data using this option:

ConvertAnalyticalSurfacesToSpline=true

[traceparts]

Hello,

> the problem is definetly in the acis/step translator, i would report a bug to spatial...

Yes, we would like to do this but we still use R16 and there is no more support for this release. We plan to move to R20, so we hope this problem is fixed in the latest release...

Anyway, thanks again for your help :)

Olivier.

[ejp]

olivier,

if you send me the acis file i can test it with the latest interop r20sp1 to see if there is still a problem in the resulting step file...