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Harris Geospatial / Docs Center / Libraries / Mankoff / KDM_NORTH

KDM_NORTH

KDM_NORTH

Name


KDM_NORTH

Purpose


  This procedure puts a North arrow (and letter N) on a map
  indicating which way is North.

Category


  Map, Imaging

Calling Sequence


  KDM_NORTH

Keyword Parameters


  LON: The desired longitude of the tail of the arrow
  LAT: The desired latitude of the tail of the arrow

Side Effects


  Draws an arrow and the letter "N" on the current map display

Restrictions


  Must have a map projection set up (for example, with MAP_SET)

Procedure


  1) Find the lat/lon bounds of the map
  2) If no lat/lon for arrow tail specified, then use the point at
    (0.2, 0.8) (where (0,0) is the bottom left and (1,1) is the top
    right corner of the map)
  3) Calculate an offset so the arrow is 10% of the map
  4) Convert the head and tail to a great circle path (map_2points)
  5) Plot it, add the arrow, and add the letter "N"

Example


  MAP_SET, /MOLLWEIDE, 40,-50, /GRID, SCALE=75e6,/CONTINENTS
  map_continents
  map_grid, glinestyle=0, color=254
  kdm_north, color=253, thick=4, charth=4 ; default location
  KDM_NORTH, lon=0, lat=0 ; at (0,0)

Modification History


  Written by: Ken Mankoff, 2009-02.
  2010-02-02: KDM Added documentation. Fixed bug where setting lat=0
                  or lon=0 used default location instead.



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