ENVIStandardRasterSpatialRef::ConvertMapToFile

The ConvertMapToFile method converts the following within a standard spatial reference:

Geographic coordinates (x=longitude, y=latitude) to file (pixel) x,y coordinates
Projected coordinates (x=eastings, y=northings) in linear units to file (pixel) x,y coordinates

Example

The following example converts a set of projected coordinates to file coordinates within the same spatial reference.

; Launch the application

e = ENVI(/HEADLESS)

; Open a file

file = FILEPATH('qb_boulder_msi', ROOT_DIR=e.ROOT_DIR, $

  SUBDIRECTORY = ['data'])

raster = e.OpenRaster(file)

spatialRef = raster.spatialRef

; Provide a set of projected coordinates

MapX = 481874.4000D

MapY = 4428160.8000D

spatialRef.ConvertMapToFile, MapX, MapY, FileX, FileY

PRINT, 'Map coordinates: ',MapX, MapY

PRINT, 'File coordinates: ',FileX, FileY

The next example converts a set of geographic (latitude/longitude) coordinates to file coordinates within the same spatial reference.

; Launch the application

e = ENVI(/HEADLESS)

; Open a file

file = FILEPATH('GMTED2010.jp2', ROOT_DIR=e.ROOT_DIR, $

  SUBDIRECTORY = ['data'])

raster = e.OpenRaster(file)

spatialRef = raster.spatialRef

; Provide a set of geographic coordinates

MapX = 72.0D

MapY = 35.0D

spatialRef.ConvertMapToFile, MapX, MapY, FileX, FileY

PRINT, 'Map coordinates: ',MapX, MapY

PRINT, 'File coordinates: ',FileX, FileY

Syntax

ENVIStandardRasterSpatialRef.ConvertMapToFile, MapX, MapY, FileX, FileY

Arguments

MapX

For a projected coordinate system, specify the x-coordinate (easting) in meters or feet. 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]

For a geographic coordinate system, specify the x-coordinate (longitude) in decimal degrees. 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 = [-112.0D, -83.0D]

MayY = [-39.0D, -37.0D]

MapY

For a projected coordinate system, specify the y-coordinate (northing) in meters or feet. For a geographic coordinate system, specify the y-coordinate (latitude) in decimal degrees.

FileX

A named variable that contains the pixel x-coordinate

FileY

A named variable that contains the pixel y-coordinate

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