McIDAS Learning Guide
Version 2015

## Graphics and the Cursor - Finding Distances Between Points

In this exercise, you will use the cursor and the DIST command to find the distance between points on a navigated frame. When using the DIST command, it is useful to type the commands while the image window is raised.
1. Click in the image window to raise it to the foreground.

2. Position the cursor at Raleigh-Durham, North Carolina and start the DIST command. Press Alt-G to enter Raleigh-Durham as the starting point for measuring the distances.
Type:  PC L KRDU;DIST
Press:  Alt G
3. Position the cursor at Bangor, Maine. Then press the middle mouse button or Alt-G to measure the distance from Raleigh-Durham to Bangor.
Type:  PC L BGR
Press:  Alt G
A distance of 1296 kilometers is marked on the frame and also listed in the text window with the latitude and longitude measurements.

4. Position the cursor at New York City. Then press Alt-G to measure the distance from New York City to the starting point (Raleigh-Durham, 680 km) and to the previous point (Bangor, 616 km). Until you reset the starting point, all of the starting point measurements will be made from Raleigh-Durham.
Type:  PC L NYC
Press:  Alt G
5. Press the right mouse button to clear the starting point. Then position the cursor at New York City and press the middle mouse button or Alt-G to set New York City as the new starting point.
Press:  < right mouse button >
Type:  PC L NYC
Press:  Alt G
6. Position the cursor at Cincinnati, Ohio, and press the middle mouse button or Alt-G to measure the distance from New York City to Cincinnati.
Type:  PC L LUK
Press:  Alt G
The distance from New York City to Cincinnati (906 km) is calculated.

7. End the DIST command by pressing the middle and right mouse buttons, or:
Press:  Alt Q
8. Position the cursor at Raleigh-Durham and draw a circle encompassing the area within 100 km of the point.
Type:  PC L KRDU;DIST CIR X X 100
This is useful for quickly determining the approximate distance between a weather system and a particular location, as shown below.

9. Exit McIDAS.
Type:  EXIT