ENVIGridDefinition::ConvertGridToMap

This function method returns the map coordinates for a given (row, column) index.

Example

; Start the application

e = ENVI(/HEADLESS)

; Select input data

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

  SUBDIRECTORY = ['data'])

raster = e.OpenRaster(file)

; Retrieve the grid parameters of the raster

PixelSize = raster.SPATIALREF.PIXEL_SIZE

CoordSysString = raster.SPATIALREF.COORD_SYS_STR

NumRows = raster.NROWS

NumCols = raster.NCOLUMNS

TiePointMap = raster.SPATIALREF.TIE_POINT_MAP

TiePointPixel = raster.SPATIALREF.TIE_POINT_PIXEL

CoordSys = ENVICoordSys(COORD_SYS_STR=CoordSysString)

; Create a grid definition for the original raster

Grid = ENVIGridDefinition(CoordSys, $

  PIXEL_SIZE=PixelSize, $

  NROWS=NumRows, $

  NCOLUMNS=NumCols, $

  TIE_POINT_MAP=TiePointMap, $

  TIE_POINT_PIXEL=TiePointPixel)

; Get the map coordinates

; for pixel location (120,50)

Grid.ConvertGridToMap, 119,49,x,y

PRINT, x,y

IDL prints:

480600.40       4428841.2

Syntax

ENVIGridDefinition.ConvertGridToMap, Column, Row, X, Y

Arguments

Column

Specify a zero-based column number.

Row

Specify a zero-based row number.

X

A named variable containing the x location (easting or longitude)

Y

A named variable containing the y location (northing or latitude)

Keywords

Keywords are applied only during the initial creation of the object.

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 5.2

Introduced

API Version

4.2