Ruler Function
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