How to use the Ruler function to measure a segment or an area.

The Ruler tool calculates distance and area and is available in any mode.

A baseline measurement of a known distance, e.g. the diameter of a contact lens, is required. Measurements are taken in mm or microns. 

Activate Ruler: Segment Measurement

Step 1: Take an external measurement across the eye, for example, a contact lens.

Step 2: Click Ruler to activate the tool, Figure 1.

Figure 1

Input Baseline Ruler Measurement: Segment Measurement

Step 1: Then click on the image to drop an anchor point and drag the line across the image.

Step 2: Double-click in the box above the drawn line and enter the external baseline measurement, Figure 2.

Figure 2

Ruler Calculations: Segment Measurement

Step 1: You will see the ruler now has an applied value. Move the primary ruler to the area measured externally and adjust its length to suit, Figure 3. 

Step 2: Now select your area to draw your second line and click once, now this will bring up a prompt box requesting you to select either Line or Area. In this case, select the Line as shown in Figure 4.

Step 3: Next the user can now use the secondary ruler to measure other areas of the image, as shown in Figure 5.

Figure 3

Figure 4

Figure 5

 

Ruler: Area measurement 

Note: You will need to take an external measurement across the eye, for example, a contact lens, before using this function 

Step 1: Take an external measurement across the eye, for example, a contact lens.

Step 2: Click Ruler to activate the tool, Figure 1.

Step 3: Then click on the image to drop an anchor point and drag the line across the image.

Step 4: Double-click in the box above the drawn line and enter the external baseline measurement, Figure 2.

Step 5: You will see the ruler now has an applied value. Move the primary ruler to the area measured externally and adjust its length to suit, Figure 3. 

Step 6: Now select your area to draw your second line and click once, now this will bring up a prompt box requesting you to select either Line or Area. In this case, select the Area as shown in Figure 6.

Step 7: From here continue to move the mouse and left click in intervals to form a border around the desired area.  

Step 8: To finish, make your way around to the first anchor point (largest square) and click to complete the selection. Alternatively, you can right-click at any point to auto-complete.  

Step 9: When the area is closed, the measurement is displayed, Figure 7.

Note: this mode will only create straight lines. To cover more detailed areas, click more often to place more anchor points.

Figure 6

Figure 7