Hi Peter, unfortunately there is no mechanism inside of the .obj file format to describe the unit system of the numbers that are stored in it.

So whatever you export is just saved as plain numeric data, regardless of the unit system that you have set in MoI.

Different programs may interpret it in different ways, some may have a setting in import options so that you can manually tell it what unit system the file's coordinates are in.


One thing that may help - you can apply an automatic scale factor to OBJ exports, this is set under Options / OBJ options / Scale factor. So for instance if your OBJ export is coming in 100 times too big when read into Kerkythea, put a scale factor of 0.01 in there, and that will scale it down at export time for you automatically after that.


> You can imagine that for rapid prototyping the right size is essential !

Actually even the STL file format that was invented specifically for use with rapid prototyping does not contain any units information in it, you generally have to have the units tracked or agreed upon separately from the file itself.

- Michael