Jump to content


- - - - -

IGES/IGS export settings

iges igs export brep breps

  • Please log in to reply
8 replies to this topic

#1 Mr. Harry Linskens

Mr. Harry Linskens

    Newbie

  • Members
  • Pip
  • 5 posts

Posted 19 August 2016 - 09:51 AM

Hi everyone,

 

I have a hull form in CAESES as a Brep object, which I would like to export as an IGES file. However, the program I need the IGES for has a very specific set of requirements regarding the included IGES entity types and spatial tolerance settings.

 

Is there any way that I can modify these settings for the IGES Export in CAESES?

 

Cheers!

 

 


  • 0

#2 Stefan Wunderlich

Stefan Wunderlich

    Moderator

  • Moderators
  • 82 posts

Posted 19 August 2016 - 01:24 PM

Hi Harry,

 

Currently there are no additional setting for the IGES-export.

Could you tell us a bit more about the needed IGES specification and what software you try to use. Maybe we can do something ...

 

Cheers,

Stefan


  • 0

#3 Mr. Harry Linskens

Mr. Harry Linskens

    Newbie

  • Members
  • Pip
  • 5 posts

Posted 23 August 2016 - 07:30 AM

Hi Stefan,

 

I would like to import the IGES file into the ship stability software NAPA, which can be a bit picky with the geometry it will read.

 

NAPA only supports a few types of IGES entities, being NURBS surfaces (entity 128), polynomial surfaces (entity 114), and trimmed surfaces (entity 144). I think that it would work best with NAPA if the shape could be exported as a trimmed surface. Could you maybe explain a little how CAESES treats a Brep object when it is exported as an IGES?

 

Also, NAPA requires a fairly coarse tolerance in the IGES file (0.01 m) to function properly.

 

Cheers,

Harry


  • 0

#4 Stefan Wunderlich

Stefan Wunderlich

    Moderator

  • Moderators
  • 82 posts

Posted 24 August 2016 - 07:50 AM

Hi Harry,

 

Have you already tried to read an IGES file exported by CAESES in NAPA? Have there been any Problems?

 

As far as I know, all surface types are exported as type 128 and breps as trimmed surfaces. Maybe you can take a simple hull model and export it as surfaces and as well put the surfaces inside a brep and export the brep to see which works better (you can also set the tolerance at the brep but this setting might introduce problems in the brep itself).

 

Unfortunatly I do not have NAPA, so I can't try it myself but I an most interested in the results.

 

Cheers,

Stefan


  • 0

#5 Mr. Harry Linskens

Mr. Harry Linskens

    Newbie

  • Members
  • Pip
  • 5 posts

Posted 24 August 2016 - 03:04 PM

Hi Stefan,

 

As you suggested, I made a simple hull form in CAESES, and then exported both the surfaces and a Brep made of the surfaces as IGES files. I used the default settings for the Brep object. Looking at the two exported IGES files in Rhino V5, the shapes seem identical.

 

When I try to import the shapes into NAPA, the IGES created from the surfaces is read without a problem. However, NAPA refuses to read the IGES created from the Brep. I am not that familiar with the specifics of the IGES format, but there must be some kind of difference in definition between the two export methods, even though they both seem to be good in Rhino.

 

For some reason, I am not able to attach the two IGES files I made. Is there a way that I can share these files with you? I would really appreciate any help you could offer!

 

Cheers,

Harry


  • 0

#6 Karsten Wenzke

Karsten Wenzke

    Moderator

  • Moderators
  • 269 posts
  • LocationBerlin

Posted 25 August 2016 - 10:04 AM

Dear Harry,

 

You can create a zip archive and upload them again. There are some upload restrictions to file endings and the maximum size of the attached files.

 

In the end it is a matter of the Napa Iges interpreter.

 

Cheers,

Karsten


  • 0

Karsten Wenzke B.Eng.
Service and Support
Engineer
 

Contact me on Linkedin.

 

www.friendship-systems.com
TEL. +49 (0)331 967 66 0

 


#7 Mr. Harry Linskens

Mr. Harry Linskens

    Newbie

  • Members
  • Pip
  • 5 posts

Posted 25 August 2016 - 12:27 PM

Hi Karsten,

 

Thanks, I've included the .zip with both IGES files in it.

 

I've taken a closer look at both files. The IGES exported from the surfaces contains 10 rational bspline surfaces (entity 128), as I would expect from the used shape. The IGES exported from the Brep, however, contains 10 loops (entity 508), 10 faces (entity 510), and a bunch of rational bspline curves (entity 126), along with the 10 bspline surfaces. I'm guessing that all these extra entities are what NAPA is having trouble with.

 

Would it be possible to have CAESES just export the bspline surface entities from the Brep object to an IGES file?

 

Cheers,

Harry

Attached Files


  • 0

#8 Karsten Wenzke

Karsten Wenzke

    Moderator

  • Moderators
  • 269 posts
  • LocationBerlin

Posted 25 August 2016 - 01:23 PM

Hey Harry,

 

It is not possible to have such an export option in CAESES. As you wrote the bspline curves are in the iges and it is also correct to have all the other entities as well because they are need to be able to recreate the brep.

Rhino can read both iges files.

You have two options now in my opionion:

 

1) Model the ship only with surfaces in caeses then you do not have the problem at all.

Why do use the brep to model the ship? In general the brep is not needed until you need to have a watertight geometry or need to cut a hole in the hull.

 

or 2)  Contact the Napa support and make them aware that their Iges Interpreter has some trouble with the iges file and maybe they can do something about it.

If you like you can share the project with us here in the forum or send it to me via mail then I'll be able to give some advices.

 

Cheers,

Karsten


  • 0

Karsten Wenzke B.Eng.
Service and Support
Engineer
 

Contact me on Linkedin.

 

www.friendship-systems.com
TEL. +49 (0)331 967 66 0

 


#9 Mr. Harry Linskens

Mr. Harry Linskens

    Newbie

  • Members
  • Pip
  • 5 posts

Posted 26 August 2016 - 07:40 AM

Hi Karsten,

 

Indeed, when I have the option of making the hull shape myself, such as for the sample files I sent, I can simply export the surface objects themselves and load the resulting IGES into NAPA without problems.

 

However, I often have to work with geometry that has been provided by another party in a different format, such as a Parasolid. Where NAPA cannot read Parasolid files, CAESES can. Therefore, I was attempting to use CAESES to convert the Parasolid file into a format which NAPA can read, the most feasible of which was an IGES file. As Parasolid files are imported into CAESES as Brep objects, this lead to my initial question.

 

In any case, thank you for your help, and I will contact NAPA support to see if they can do anything about their IGES interpreter. If you have any other ideas on how to handle this type of process, I am open to suggestions :).

 

Cheers,

Harry


  • 0





Also tagged with one or more of these keywords: iges, igs, export, brep, breps