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The ConvertLonLatToLonLat method converts a set of geographic latitude/longitude coordinates in one spatial reference to the same location in another spatial reference. The associated ENVIRasters' metadata must include a coordinate system string.

Pseudo map information refers to a non-standard projection that involves an affine map transformation. When an image is not georeferenced to a standard map projection and you only know the geographic coordinates and map projection of four points in the image, you can define these tie points in an ENVI header file or in the metadata of the raster object. ENVI will use these points to warp the image and to calculate geographic coordinates for each pixel. The pixel size varies in the rectified image. This type of projection contains a high degree of variability and is not geographically accurate; the (x,y) locations in the rectified image are only best guesses.


ENVIPseudoRasterSpatialRef.ConvertLonLatToLonLat, Lon1, Lat1, Lon2, Lat2, SpatialRef2



The longitude coordinate in the first spatial reference. You can specify a scalar or a vector of longitude values; if it is a vector, the Lat1 argument should also be a vector with the same number of elements:

Lon1 = [-123.58, -134.64]
Lat1 = [48.23, 49.56]


The latitude coordinate in the first spatial reference


A named variable that contains the longitude coordinate in the second spatial reference


A named variable that contains the latitude coordinate in the second spatial reference


A reference to an ENVIPseudoRasterSpatialRef object in the second spatial reference



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

ENVIPseudoRasterSpatialRef, ENVIRPCRasterSpatialRef::ConvertLonLatToLonLat, ENVIStandardRasterSpatialRef::ConvertLonLatToLonLat

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