Switch to measuring mode by click the measurement icon in the toolbox at the upper left corner. To measure, click two points on the visualization screen, the physical length measurement will be calculated and saved to measuring history. The last value will also be copied to system’s clipboard so you can easily paste to other applications or the annotation.

Figure 8.7. Enable measure mode

Figure 8.8. Show measuring history

Figure 8.9. Measure on images

A screen capture video of these actions can be found in this link online (size: 5.7MB).