ENVICoordSys::ConvertMapToLonLat

The ConvertMapToLonLat method converts a set of map coordinates (x-eastings, y-northings) to a set of latitude/longitude coordinates within the same coordinate system.

Example

The following example converts a set of map coordinates in a vector file to lon/lat coordinates.

; Launch the application

e = ENVI(/HEADLESS)

file = FILEPATH('qb_boulder_msi_vectors.shp', $

  SUBDIRECTORY = ['data'], ROOT_DIR=e.Root_Dir)

; Create an ENVIVector from the shapefile data

vector = e.OpenVector(file)

; Retrieve a reference to the coordinate system

VectCoords=vector.COORD_SYS

; Provide a set of map coordinates

MapX = 482186.3200D

MapY = 4428133.6400D

VectCoords.ConvertMapToLonLat, MapX, MapY, Lon, Lat

PRINT, 'Map coordinates: ',MapX, MapY

PRINT, 'Lon/Lat coordinates: ',Lon, Lat

Syntax

ENVICoordSys.ConvertMapToLonLat, MapX, MapY, Lon, Lat

Arguments

MapX

The map x-coordinate (easting). You can specify a scalar or a vector of MapX values; if it is a vector, the MapY argument should also be a vector with the same number of elements:

MapX = [481874.4000D, 482260.8000D]

MapY = [4428160.8000D, 4427992.8000D]

MapY

The map y-coordinate (northing)

Lon

A named variable that contains the longitude value

Lat

A named variable that contains the latitude value

Keywords

ERROR

Set this keyword to a named variable that will contain any error message issued during execution of this routine. If no error occurs, the ERROR variable will be set to a null string (''). If an error occurs and the routine is a function, then the function result will be undefined.

When this keyword is not set and an error occurs, ENVI returns to the caller and execution halts. In this case, the error message is contained within !ERROR_STATE and can be caught using IDL's CATCH routine. See IDL Help for more information on !ERROR_STATE and CATCH.

See Manage Errors for more information on error handling in ENVI programming.

Version History

ENVI 5.1

Introduced

API Version

4.2