Measurements at non-visible entities

Possibly, though it sounds more likely to be an issue with your graphics card / drivers. If you can post a copy of the file online and link to it (without breaking copyright or confidentiality) we can see if it works, but the first thing would be to make sure you have your graphics drivers fully updated.

It might also be worth switching the 3D viewport display style (shaded, wireframe, illustration, etc.) to see if that makes a difference - the less texture and shadow detail the card has to handle, the better it'll behave if it's struggling with a complex model.

I am very sorry because of the large break since my last post.

This phenomenon occures on different machines, I assume it not to be in relation to my graphics card. Now there are some simple examples including this problem:

http://www.home.hs-karlsruhe.de/~haeb0001/files/a01.pdf

http://www.home.hs-karlsruhe.de/~haeb0001/files/Greifer1.pdf

http://www.home.hs-karlsruhe.de/~haeb0001/files/Schweisszange.pdf

Switching the 3D viewport style does not really help. My next experiment could be to create 3D objects by using different software. These examples are produced with ANSYS via an IGES-File.

Hello,

This is a bug from the Overlay.
The workaround is the following :
Click on the 3D scene (active the 3D annotation) - then right mouse button (popup)-> select properties
within the 'appearance' field, UNcheck 'transparent Background'
Then you will be able to do measurements.....

Hope this is Helpful.

I am having a problem with Acrobat Pro 7.0:
It has shut down the ability to set scale. What do I do?

Under Preferences > Measuring (2D) have you got the box checked (use scale from document when present)?