This article explains what an HGT file is and how it is used. It also explains how to open an HGT file on your computer and how to convert it to another format.
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A file with the HGT file extension is a Shuttle Radar Topography Mission (SRTM) Data file.
These files contain digital elevation models, which are 3D images of a surface, usually a planet, created during the Shuttle Radar Topography Mission (SRTM) by NASA and the National Geospatial-Intelligence Agency (NGA).
As used here, "HGT" is simply an abbreviation for "height." The file is normally named with the latitude and longitude to which the image refers, within one degree. For example, the file N33W177.hgt would indicate that it contains data for latitudes 33 to 34 north and longitudes 177 to 178 west.
