Measurement question?

 From:  Michael Gibson
4642.3 In reply to 4642.1 
Hi mash,

> Hi, if I bring in a IGES file and set the unit system to
> Centimeters how accurate would the measurements be?

Pretty darn accurate... I guess I would need some more information to try and give you a more precise answer.

What unit system is the IGES file itself set with?

If you change the unit system there will be a scaling operation applied to all the coordinates of all the geometry, but that's a high precision operation and won't affect any measurements to any detectable level unless you've got some kind of unusual case like something with extremely large or extremely small coordinates in it.

> I'm assuming because it's an IGES file used for manufacturing
> it would be accurate.

Well, that may be a kind of big assumption - it's not unusual for a lot of the geometry that is generated by a CAD program to be accurate to a particular tolerance level. So unless everything in the IGES file is only made up of really simple primitives like all boxes or all spheres or something like that, there will be a particular accuracy level that the object has been constructed with.

So it's kind of over simplifying to just say that "it's accurate" like that's an on/off switch.

And of course it depends on what practices were followed by the people who made the geometry that's stored in the IGES file as well.

But yes, normally it's the case that IGES files contain the actual NURBS surface data that was used to construct the object, it's usually the full model data and not some approximation of the original model.

Just keep in mind that often times any particular model will probably have been constructed with some kind of tolerance level for how accurate things like the intersection curves between 2 surfaces have been calculated to.

> Is there any way to measure objects other than counting
> grid squares?
> thanks

Like Burr mentions, selecting the object will show its size in x/y/z in the object properties panel in the upper right corner of the screen. You can also click on that line to pop out a panel which will show the size to a higher precision using 4 decimal places.

If you want to measure a particular direction the easiest way to do that is to draw a line and then see the length of that line you just drew.

In the future I also want to add more methods for measuring objects - doing a lot of object analysis and measurements really isn't a focus area for MoI right now, MoI is much more focused on drawing things and creating new geometry currently.

- Michael