This routine has been replaced with one of the following objects, depending on the type of spatial reference (standard, RPC, or pseudo):

ENVIStandardRasterSpatialRef
ENVIRPCRasterSpatialRef
ENVIPseudoRasterSpatialRef

Use this function to create an ENVI Classic projection structure for any of the supported projections. You should use this function instead of accessing the projection structure directly.

Syntax

Result = ENVI_PROJ_CREATE([, /ARBITRARY] [, DATUM=value] [, /GEOGRAPHIC] [, /MAP_BASED] [, NAME=string] [, PARAMS=array] [, PE_COORD_SYS_CODE=integer] [, PE_COORD_SYS_STR=string] [, /SOUTH] [, /STATE_PLANE] [, TYPE=integer] [, UNITS=integer] [, /UTM] [, ZONE=integer])

Keywords

ARBITRARY (optional)

Set this keyword to create an Arbitrary projection. See the keyword MAP_BASED below.

DATUM

Use this keyword to specify the datum for the map information projection. The default for a Geographic projection is WGS-84, and the default for UTM and State Plane projections is North America 1927 (NAD27). All other projections default to no datum. The exact name that ENVI Classic uses for each datum is listed in the datum.txt file in the map_proj directory of your ENVI Classic installation.

GEOGRAPHIC (optional)

Set this keyword to create a Geographic projection.

MAP_BASED (optional)

Set this keyword to interpret the Arbitrary projection as map-based. This keyword does not have any effect for other projections. The default is a non-map based projection. A map-based projection uses the lower-left corner of the image as the projection origin, while a pixel-based projection (non-map based) uses the upper-left corner as the origin.

NAME

Use this keyword to specify a name for the projection. NAME is a string variable. The actual projection type is not determined by the value of NAME. Instead, the projection type is determined by the keyword TYPE, ARBITRARY, GEOGRAPHIC, STATE_PLANE, or UTM.

PARAMS (optional)

Use this keyword to specify the parameters for the map information projection. PARAMS is a array of double-precision values with 1 to 15 elements. The number of elements is determined by the projection type (see the TYPE keyword). Do not use PARAMS with Arbitrary, Geographic, State Plane, or UTM projections. The PARAMS keyword must contain all projection parameters listed in Map Projections (for the specified projection) except the datum and name. The datum and name are specified using the DATUM and NAME keywords, respectively.

PE_COORD_SYS_CODE (optional)

Use this keyword to pass in a valid geographic (GEOGCS) or projected (PROJCS) coordinate system code, typically a five-digit number.

For a full list of coordinate system strings and codes, refer to the following text files in the \IDLxx\resource\pedata\predefined directory of the ENVI distribution:

  • EnviPEProjcsStrings.txt: PROJCS codes and strings
  • EnviPEGeogcsStrings.txt: GEOGCS codes and strings

Set the TYPE keyword to 1 when passing in a GEOGCS code, or set TYPE to 42 when passing in a PROJCS code.

PE_COORD_SYS_STR (optional)

Use this keyword to pass in a a geographic (GEOGCS) or projected (PROJCS) coordinate system string.

For a full list of coordinate system strings and codes, refer to the following text files in the \IDLxx\resource\pedata\predefined directory of the ENVI distribution:

  • EnviPEProjcsStrings.txt: PROJCS codes and strings
  • EnviPEGeogcsStrings.txt: GEOGCS codes and strings

Set the TYPE keyword to 1 when passing in a GEOGCS string, or set TYPE to 42 when passing in a PROJCS string. See Example.

SOUTH (optional)

Set this keyword to specify that the UTM projection is in the southern hemisphere.

STATE_PLANE (optional)

Set this keyword to create a State Plane projection.

TYPE (optional)

Use this keyword to specify the projection type. TYPE is an integer value corresponding to the projection type. See Coordinate System Strings and Codes for more information.

UNITS (optional)

Use this optional integer keyword to specify the projection units. The function ENVI_TRANSLATE_PROJECTION_UNITS converts projection unit strings to integer values. The default units are degrees for Geographic, feet for State Plane, and meters for all other projections.

UTM (optional)

Set this keyword to create a UTM projection.

ZONE (optional)

Use this keyword only with UTM and State Plane projections to specify the zone number.

API Version

4.2