Alternate units dim bug

I have a file which my model space units are cm, layout space units are inches (we are building in metric, but a lot of the design is being done and proofed here, so printed imperial sized paper). My dimensions are primary units are decimal (and a cm suffix) with a length factor of 1. My alternate units are Feet & inches with a length factor of 100/254 (0.393701).

This issue I am seeing is that the alternate units are off by a factor of 2.54 when placed (the dim will read 100.0cm [1’-3 1/2"] instead of 100.0cm [3’-3 1/2"]), but will update if I change anything in the dimension properties (for instance, if I change the precision from 1.00 to 1.000 and hit OK the dimensions will update to the correct alternate units). If I set alternate units to decimal, still keeping the 100/254 length factor, the alternate units seem to place fine and don’t need to be updated. So this seems to only affects fractional alternate units.

It doesn’t seem to matter what the layout space units are. I changed them to CM to match model space but am still seeing the bug.


Hmm, so with layout in cm, the dims alternate dims don’t update to what I was expecting when using a length factor, but if I set the length factor back to 1 (from 100/254), it works, so it seems that Rhino is trying to do my alt dim scaling automagically based on my selection of Feet & Inches.

I find this rather confusing, if I wanted decimal feet, I would have to use a length factor, but because I wanted feet & inches, I needed to set the length factor to 1. I would recommend that if you guys want to go the automagic route, make it a bit more intuitive. Instead of the current “Number format” only for both primary and alternate units, make the desired dimension units choice explicit by include a unit type pull down like seen in Options->Units->[Model/layout] Units options. This will set the length factor for the user, and the number format would only affect how the number is displayed, and not the length factor as it seems to do now.


Thanks Sam for all the input here. I agree this should be easier to figure out… decimal display of alternate text feet for example requires a length factor of 0.032808

I’ll file a feature request to have a drop down list for unit used (primary and alternate) with a separate list for the display format. Let me know if I’ve misunderstood.

Thanks Brian, you’ve got it.