Hi Michael,

There is probably an obvious answer to this, but if the units aren't defined,
why are they consistent with millimeters and come in with no unit conversion messages popping up,
when I bring a MoI model into Rhino? I've imported models from AutoCAD and other SW's
which were way out of scale.

-Jesse

Hi Jesse - in the .3dm file, MoI sets the units to a special "no unit system" value. It appears that Rhino doesn't have a way to set this in its UI, but it is available to programs writing a .3dm file.

When Rhino imports a .3dm file with this setting in it, it seems to just bring the values over into the currently defined unit system with no changes (with no unit conversion message). So for instance 3.5 will come in as 3.5 mm if your Rhino units are mm.

So it works for you because you are considering MoI's generic units to be millimeters, and your setting in Rhino is set to millimeters too, so they match up.

- Michael