MAP_PROJ_INFO Procedure

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 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_proj_info.pro in the lib subdirectory of the IDL distribution.

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:

AZ     INT  =  0

CIR     INT  =  0

CYL      INT  =  1

NAME     STRING  'Mercator'

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.

Version History

5.0	Introduced