Hi Al - it seems to involve a problem with the units specified in the IGES file - it looks like the units designator may be malformed in the file.

The IGES spec says that there is a "Units Flag" marker in the file which can contain these possible values:

Value  Model Units
1        Inches (default)
2        Millimeters
3        (See Parameter 15 for name of units)
4        Feet
5        Miles
6        Meters
7        Kilometers
8        Mils (i.e., 0.001 inch)
9        Microns
10      Centimeters
11      Microinches


For this particular file, the units flag has a value of 3, so that means that the next "Units Name" field (parameter 15 in the global section) is supposed to contain a units name label. But instead of any actual label there in your particular file there seems to only be a single space character there where the units name is supposed go.

The IGES spec says: "When field 14 is 3, the string naming the desired unit shall conform to [MIL12] or [IEEE260]."

I don't have those documents handy right now, but it seems unlikely that a space character will actually be listed in them as a valid unit name...

So from what I can see, this IGES file does not seem to be quite in spec with regards to the units label. That probably also explains why some programs are seeing the units differently - it looks like Delcam which Burr shows the diagnostic from above thinks the units are in MM while Rhino thinks the units are in inches.

If this is something that is part of one of your own products, you may want to fix it up so that it has a proper unit system designator in it, that will then probably help get the units going across consistently into different programs.

The reason why it doesn't work in MoI v3 is that an update to the IGES parser tries to read in IEE260 format units and then that throws an error which then errors out the entire import process. I should be able to get that fixed up so that an error there does not stop the import from working at all and instead uses a default unit system, I guess probably inches since that's normally the default in IGES.

But it would also probably be good to get the units designator fixed up so that it's not out of spec as well though.

- Michael

Hi Al, or also if you happen to know for sure that a space character is actually a valid units label in either of those labeling systems, let me know if that is actually the case so I can get that to be recognized.

[MIL12] is:
Abbreviations for Use on Drawings, Specifications, Standards, and in Technical Documents
(MIL-STD-12D), U.S. Department of Defense, May 1981.


And [IEE260] is:
IEEE Standard Letter Symbols for Units of Measurement (ANSI/IEEE Std 260),
Institute of Electrical and Electronics Engineers, 1978.


But those are all about abbreviations and letter symbols for different units - it seems pretty unlikely that a blank space character would be listed in either of them as a type of unit system abbreviation.


- Michael

Hi Al - for the next v3 beta I've got it tuned up now so that it will ignore any problem in parsing the units instead of letting that derail the entire import. So in the next v3 beta this file will import again.

Thanks for supplying a simple example file for testing with.

- Michael

Hello to all,

It does import fine into ViaCAD 2D/3D v8:

Michael,

Thanks for looking at this. You are correct that the "blank" units should not be there. I should have caught that and I can force it to be right. When I do this it imports fine in V3.

Al