Change the Measuring preferences to determine how 3D data is measured. These options appear in the Measuring (3D) panel of the Preferences dialog box.
Displays measurements based on the model units, if present, generated from the original 3D model. Deselect this option to specify the units of measurements manually. This setting can be changed in the 3D Measurement Tool palette.
Uses units of measurement that you specify here rather than those in the 3D model.
Determines what kind of data is measured in the 3D Measurement Tool palette.
Specifies the color of the line that appears when you click or drag to measure an object.
Turns on snap and specifies whether points, arcs, edges, or silhouette edges are snapped to. Sensitivity indicates how close the pointer needs to be to the item being snapped to. For Snap Hint Color, specify the color of the snap line that appears when you hold the pointer over the 3D object.