The ConvertMapToLonLat method converts a set of map coordinates (x-eastings, y-northings) to a set of geographic latitude and longitude coordinates within a standard spatial reference. The associated ENVIRaster's metadata must include a coordinate system string.


The following example converts a set of map coordinates to lon/lat coordinates within the same spatial reference.

; Launch the application
; Open a file
file = FILEPATH('qb_boulder_msi', ROOT_DIR=e.ROOT_DIR, $
  SUBDIRECTORY = ['data'])
raster = e.OpenRaster(file)
spatialRef1 = raster.spatialRef
; Provide a set of map coordinates
MapX = 481874.4000D
MapY = 4428160.8000D
spatialRef1.ConvertMapToLonLat, MapX, MapY, Lon, Lat
PRINT, 'Map coordinates: ',MapX, MapY
PRINT, 'Lon/Lat coordinates: ',Lon, Lat


ENVIStandardRasterSpatialRef.ConvertMapToLonLat, MapX, MapY, Lon, Lat



The map x-coordinate. 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]


The map y-coordinate


A named variable that contains the longitude value


A named variable that contains the latitude value



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


API Version


See Also

ENVIStandardRasterSpatialRef, ENVIPseudoRasterSpatialRef::ConvertMapToLonLat, ENVIRPCRasterSpatialRef::ConvertMapToLonLat