This Map Container demonstrates both how to build an empty map

covering whole US with a scale of 1:500 000.

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How did I get the parameters?



First I have defined the geographic borders for the map, I have

used a south border of 25 degrees north, a north border of

55 degrees north, a west border of 125 degrees west and an

east border of 65 degrees west.



Next I have translated the degree deltas into pixels.



Latitude degrees have a constant distance of 111 kilometers,

therefore the height of the map is 11 100 000 centimeters *

(50 - 25) degrees = 277 500 000 centimeters. We have a scale of

1:500 000, therefore the height is reduced to 555 centimeters.

As stated within the manual  one centimeter is 28.346 pixels,

therefore our map has a height of 15732 pixels.



Longitude degrees have no constant distance. At the equator they

also have a distance of 111 kilometers, but longitude lines meet at

the poles. To get the approximate distance at a given latitude

you must multiply 111 000 kilometers by COS (latitude).

Based on a latitude of 37.5 degrees, which is the middle between

25 and 50 degrees, the width of the map is 11 100 000 centimeters *

(125 - 65) degrees * COS ((25 + 50) / 2) = 528 373 325 centimeters.

We have a scale of 1:500 000, therefore the width is reduced to

1057 centimeters.

As stated within the manual  one centimeter is 28.346 pixels,

therefore our map has a width of 29962 pixels.



Remember: These Longitude values must be entered as negative

because they are located at the west hemisphere!



Logitude Latitude    X       Y

================================

 -125.0     25.0      0   15732 

  -55.0     25.0  29962   15732

 -125.0     50.0      0       0





"RectMap" output:

=================

                      C_X         : [ 5.3503571429E+04,  4.2802857143E+02, -0.0000000000E+00],

                      C_Y         : [ 3.1464000000E+04, -6.2928000000E+02,  0.0000000000E+00],

                      C_Long      : [-1.2500000000E+02,  2.3362926373E-03,  0.0000000000E+00],

                      C_Lat       : [ 5.0000000000E+01, -1.5891177218E-03,  0.0000000000E+00],

                      A           : -0.0,