MAP_PROJ

MAP_PROJ_INFO

The MAP_PROJ_INFO procedure returns information about the current map and/or the available projections.

Note

The MAP_PROJ_INFO procedure is compiled along with the MAP_SET procedure. You must call the MAP_SET procedure to set up mapping parameters before calling MAP_PROJ_INFO.

This routine is written in the IDL language. Its source code can be found in map_set.pro in the lib subdirectory of the IDL distribution.

Syntax

MAP_PROJ_INFO [, iproj] [, AZIMUTHAL=variable] [, CIRCLE=variable] [, CYLINDRICAL=variable] [, /CURRENT] [, LL_LIMITS=variable] [, NAME=variable] [, PROJ_NAMES=variable] [, UV_LIMITS=variable] [, UV_RANGE=variable]

Arguments

Iproj

The projection index. If the CURRENT keyword is set, then the index of the current map projection is returned in Iproj.

Keywords

AZIMUTHAL

Set this keyword to a named variable that, upon return, will be set to 1 if the projection is azimuthal and 0 otherwise.

CIRCLE

Set this keyword to a named variable that, upon return, will be set to 1 if the projection is circular or elliptical and 0 otherwise.

CURRENT

Set this keyword to use the current projection index and return that index in Iproj.

CYLINDRICAL

Set this keyword to a named variable that, upon return, will be set to 1 if the projection is cylindrical and 0 otherwise.

LL_LIMITS

Set this keyword to a named variable that will contain the geocoordinate rectangle of the current map in degrees, [Latmin, Lonmin, Latmax, Lonmax]. This range may not always be available, especially if the LIMIT keyword was not specified in the call to MAP_SET. If either or both the longitude and latitude range are not available, the minimum and maximum values will be set to zero.

NAME

Set this keyword to a named variable that will contain the name of the projection.

PROJ_NAMES

Set this keyword to a named variable that will contain a string array containing the names of the available projections, ordered by their indices. The first projection name is stored in element one.

UV_LIMITS

Set this keyword to a named variable that will contain the UV bounding box of the current map, [Umin, Vmin, Umax, Vmax].

UV_RANGE

Set this keyword to a named variable that will contain the UV coordinate limits of the selected map projection, [Umin, Vmin, Umax, Vmax]. UV coordinates are mapped to normalized coordinates using the system variables !X.S and !Y.S. These limits are dependent upon the selected projection, but independent of the current map.

Examples

; Establish a projection 
MAP_SET, /MERCATOR 
 
;Obtain projection characteristics 
MAP_PROJ_INFO, /CURRENT, NAME=name, AZIMUTHAL=az, $ 
CYLINDRICAL=cyl, CIRCLE=cir

On return, the variables will be set as follows:

AZIM     INT  =  0 
CIRC     INT  =  0 
CYL      INT  =  1 
NAME     STRING  'Mercator'

Version History

Introduced: 5.0