Hi B-W-Design, did you ever find a solution to your AI export problem?

I did a bunch of tests over here and I have not been able to find any problems with MoI's export.

I tested by exporting a 5mm by 5mm square with "Projection view: Top" and "Fit to page" disabled, to generate the attached .ai file (5_by_5_mm_square.ai).

Then I tested importing this file into Rhino, ViaCAD, Creature House Expression v3, and also Adobe Illustrator CS. In all these cases the square came in at a size of 5mm by 5mm as expected.

Which program are you trying to import into, is it Cinema4D?

I noticed that unlike the other programs I tested with above, Cinema4D seems to have a problem where it scales the result by a kind of arbitrary amount instead of preserving the scale. This is not too unexpected actually since AI files internally use a kind of odd type of typographic units called "points", where 1 pt = 1/72 of an inch, so the numeric values of coordinates in the file can tend to be rather large if you don't scale them in some way (like typically points will have values like 800.2,1200.5 - kind of larger numbers). Actually MoI will do a similar thing and scale AI imports by an arbitrary factor of 1/20 unless you have units set to inches, cm, or mm before opening the file, in which case it will scale from "points" into the current unit system to preserve scale.

C4D also behaved in the exact same way with .ai files created from scratch and saved from Rhino, Expression, and Adobe Illustrator as well as MoI so as far as I can tell this doesn't have anything to do specifically with MoI. I have attached these other files for reference.

I looked in Cinema4D's options for Adobe Illustrator, (under Edit>Preferences>Import/Export>Illustrator Import) and there did not seem to be any control available to turn off this scaling, but there is an entry there for putting in your own scale factor. If you can contact Cinema4D tech support and find out what scale factor they are applying to the import automatically you could probably enter the inverse of that in this option in C4D to fix it up. Also you may want to put in a feature request to Maxon to have an additional option to "preserve units" on AI import as well.

Alternatively to preserve scale you may need to do something like export an additional line that is of a known scale, so that you can use it as a reference inside your target program to get back to the proper scale again.

- Michael