Hi Martin, yes like Pilou mentions the dimensions that are shown at the top level are done more quickly - for solids they're based off of the display mesh and for curves they're based off of a number of sampled points.

Because that size readout is updated very frequently with every selection change, it has to be calculated quickly and it would not work very well to have a lot of delays for the more intensive and accurate calculation on every selection change.

When you pop open the menu, it does the more accurate calculation at that time for the result that is shown in the menu.

- Michael

Although now that I look at what you're getting it's not what I wrote above, you're just running into some kind of bug in the tight bounds calculator for that particular object, I have put it on my list to investigate.

- Michael

Hi Martin, While Michael looks at the calc error, here are a couple tools for you to use in this scenario.

Select your object and hit tab and type BoundingBox. This will reveal the erroneous bounds calculation for the object.

Now select the object, hit tab abd type ShrinkTrimmedSrf.

The readout will now be corrected.

Shrinking the underlying surface can be helpful in some areas but also be undesirable in others, where you may be needing to untrim surfaces and such.

FYI.

Pilou, Michael and BurrMan.

Thanks for your helpful replies - I can see it's all in-hand - and BurrMan, I'll take a look at those commands you mention. There's more to MoI than meets the eye :-)

Martin (2).