Maps and Drawings
Other than most scientific plots, maps and technical drawings have typically only one scale, i.e., the vertical and horizontal scale are identical. Maps typically indicate the corresponding length scale in some corner. Using this scale allows you to setup xyscan such that the Measure Tool displays selected distances and sizes in maps and technical drawings in the desired units (miles, inches, km, cm, ...).
To setup a map for measuring proceed as follows:
- Load the map into xyscan (or use Screen Scan).
- Select the Measure Tool

- Select User Scale in the pull-down menu.
- Position the cursor on the one end of the scale indicator on the map as shown below.

- Go to the Measure Tool window and press the Start Measuring button or press Ctrl+M (macOS: ⌘+M). xyscan will mark the start point with a marker as shown in the example below. The, move the mouse pointer back to the map and move the cursor to the other end of the scale, either by using the mouse or the arrow keys (recommended since more precise). The connector line drawn by xyscan should now equal the size of the scale indicator on the map (in the example below 0.5 miles).

- Enter the referring length indicated on the map (0.5 miles in the example above) in the scale field and press Shift+Return. This will auto-normalize the entered value (0.5), meaning it will divide it by the length (in pixel) of the scale indicator on the map. Without the shift modifier the normalization
is not performed and xyscan uses the entered value as the actual scale. To normalize the entered value one can alternatively use
Ctrl+N (macOS: ⌘+N).

Now xyscan is setup to measure any length in the plot and display the distance in "real" units (miles in the example above). Instead of the above method you can of course always calculate the scale by hand by dividing the desired length indicated on the map by the length in pixel indicated in the distance field (r). Both methods define the same scale, the first is just more convenient and quicker.
Measuring Paths
By checking the box labeled Path next to the Start/Stop Measuring button, one enters the path measuring mode (if measuring is on). Use the double click to set the anchor points. The accumulated path length is displayed in the field labeled "L". See screenshot below. The Reset button clears the path and resets the shown length. The units are the same as in the distance measuring tool. Depending on the colors of the loaded image/plot, the default color of the path might not be the best choice. Its color can be changed via the Path Color... command in the Edit menu. Pick a color that contrasts well with the image.
