I read with interest your plans for adding translator support... I have a lot of legacy data in parasolid and acis format that I'd like to get into MoI. Until your translators are implemented, what's my best choice? Also I'd like to get MoI data out and into my CAD package so I can make some CAD drawings. Suggestions?

Mike...

("The plan is that having the Rhino file format as the main file format should make it easier to use MoI within existing environments alongside Rhino. Also I benefit from other industry support for the Rhino file format too, such as www.solidworks.com/Pages/products/solutions/Rhino-to-SolidWorks.html.

"I think that Rhino's file format is really the best NURBS-based open file format available right now. At this point I didn't really have anything to gain by creating a new proprietary format. I expect to add some other file format support as the beta progresses. I've licensed the Solids++ kernel from Gary Crocker <www.integrityware.com>.")

Hi Mike, I do plan on adding additional translator support in the future, including DWG/DXF and STEP at first, and possibly acis SAT and parasolid XT later, but it will be a little while before any of that is ready.

In the meantime, MoI does support 3DM and IGES formats. A lot of CAD programs support the IGES format for data transfer, so that might work for you.

To bring your legacy parasolid and acis data into MoI, open them up in your other CAD program and export as an IGES file, then read that into MoI.

For exporting from MoI to your other CAD program, save from MoI as IGES and open it in the other program.

If your CAD program does not support IGES files, another possibility would be to use Rhino - Rhino can open the .3dm files that MoI saves and it has support for a lot more file formats.

- Michael

Thanks Michael,

Problem is, when I open up an iges file of a solid model, it's really a bunch of surfaces.

I thought the modeling in MoI was done in Solids++, a kernel similar to granite, parasolid or acis. That would allow a clean export of the solid model back into the CAD package for minor solids editing, and documentation. I lose too much solids intelligence, and gain file size bloat using iges.

Is the MoI modeling done in Solids++? I notice if I create a block, I can delete one of it's faces, something I could never do in one of the other packages.

Mike..

Hi Mike, usually there is a method that can be used to glue the individual surfaces back into a solid again. Is that not happening in your software? Which software are you using?

There are a couple of different ways that stuff can be stored in an IGES file, the most common is separate surfaces which MoI uses right now.

But it is also possible to store a solid in an IGES file, which maintains the connections between surfaces. This is not used quite as commonly as surfaces, but it would be possible for me to add an option to allow IGES exports using this style if it would help. I have attached a sample file test186.igs - can you please try this file and let me know if that comes through into your software as a single solid instead of individual surfaces?

> Is the MoI modeling done in Solids++?

Yes, it is. Although Solids++ is similar in some ways to Granite, Parasolid, or ACIS it is not quite exactly the same - it is not as focused on "parametric" or "feature based" solid modeling as much as those ones are.

- Michael

I've been igesing the files back into Unigraphics NX3. No, UG doesn't convert it back into a solid.

I can test some other packages for you if you like...

Mike...

Hi Mike, I'm not really familiar with Unigraphics, but I somewhere I found a reference to a "Surfaces to solid assistant" and a "Sew" command. It sounds like one of those should work for converting the surfaces back into a solid.

Can you find either one of those commands in there and let me know if that works?

- Michael

Yes, one can sew a solid back together. How about if I test that tomorrow for you and let you know.

Mike...

Thanks Mike - if that works then that will probably be the best method (IGES + sew) for data transfer for V1. STEP will probably work better, but that won't be until after V1 though.

- Michael

Okay, a quick test of a simple solid shows that one can in fact import the iges into UG and sew the surfaces together to come up with a valid b-rep solid. With more complex solids, or assemblies it could become prohibitively time consuming, as each surface needs to be selected. In addition, with complex models, blends may not touch, and the sew will fail.

I notice that Solids++ offers a step translator. That would be the only translator you really need, as every major cad system supports step, and the output from step can be a valid b-rep solid.

Here's a picture of the imported, sewn solid, shown in section...

Hi Mike, that's great, that looks like it should be one method that will work for now.


> With more complex solids, or assemblies it could become prohibitively
> time consuming, as each surface needs to be selected.

Do you mean you have to click them one-by-one in UG? I'm surprised they don't have any window select or "Select All" type function...


> In addition, with complex models, blends may not touch, and the sew will fail.

In general stuff like blends are calculated in MoI to a tolerance of 0.001 units. So if you have any control over the tolerance that UG sew uses, just make sure it is not less than that amount, maybe around twice that would be a good tolerance to use.

- Michael