How can I set the scale in Didger so that it is 1" = 8000 feet?

What to enter for the scale in Didger entirely depends on what your map X and Y units are. You will need to calculate the scale, and then enter it for the map:
  1. Calculate the corresponding value for your map units (see below).
  2. Select Map in the Object Manager.
  3. In the Property Manager, go to the Scale tab.
  4. Enter the calculated X or Y scale value. For example, if you wanted 1" = 8000' and your map is in feet, you would enter 8000 to the right of Map units per in. for your X or Y scale.

Example Calculations:

  • If your map is in units of feet, then you would simply type in 8000. So Map units per in. = 8000.

  • If your map is in units of meters, then you need to do some math. 8000 feet is 2438 meters. So 1"=8000' is the same as 1"=2438 meters, and you would enter Map units per in. = 2438.
  • If your map is in units of lat/long, then you need to do some slightly more complicated math. You will need to convert 8000 feet to latitude and longitude.

    1 degree of latitude is about 68.703 miles (362751 feet). So 8000 feet is about 0.02205° latitude. Insert this for the Y scale (Map units per in. = 0.02205 for the Y Scale).

    1 degree of longitude is 69.172 miles * cos(latitude). So find the latitude of the center of your map and insert it in the equation to find how much 1° of longitude is for your map. So if your central latitude value is 39.5°:

    1° longitude = 69.172 mi * cos (39.5)
                      = 365228.16 feet * 0.77162
                      = 281819 feet

    8000 feet is therefore 0.02839° longitude (at 39.5° latitude). Insert this for the X scale (Map units per in. = 0.02839 for the X Scale).

Updated: October 5, 2016

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