The 3D Measurement Tools window must be active before you can use it.
To activate or deactivate 3D Measurements:
· Select or deselect the Active check box.
Unless you close the 3D Measurement Tools window before you exit from Imagenation, the active setting and position of this window is saved. Also, if you have multiple 3D documents open, Imagenation preserves the active settings for each document as you switch between them.