The ConvertMapToFile method converts the following within a Rational Polynomial Coefficient (RPC) 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

See the example for ENVIStandardRasterSpatialRef::ConvertMapToFile. That example shows the pattern of using the ConvertMapToFile method, only you would replace the standard spatial reference with an RPC spatial reference.

## Syntax

ENVIRPCRasterSpatialRef.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

3.7