=== Q: What format should my DEM be in when using aplcorr? === '''A:'''\\ APL expects the Digital Elevation Model (DEM) to be in a 1-band ENVI BIL or BSQ file format. This is a simple binary format where the data is stored as a string of binary information with an accompanying header file that describes the number of bands / lines / samples. The DEM should be projected in WGS84 Latitude and Longitude with heights referenced to the WGS84 spheroid.