How to Open, Edit, and Convert HGT Files

Screenshot of an HGT file open in VTBuilder

 Tim Fisher

A file with the HGT file extension is a Shuttle Radar Topography Mission (SRTM) Data file.

HGT files contain digital elevation models, which are 3D pictures of a surface — usually a planet — obtained during the Shuttle Radar Topography Mission (SRTM) by NASA and the National Geospatial-Intelligence Agency (NGA).

Used here, "HGT" is just an abbreviation for "height." The .HGT file is normally named with the longitude and latitude that the image pertains to, within one degree. For example, the file N33W177.hgt would indicate that it includes data for latitudes 33 to 34 North and longitudes 177 to 178 West.

Note: SRTM Data files have nothing to do with SRT files.

How to Open an HGT File

HGT files can be opened with VTBuilder, ArcGIS Pro, and Safe Software's FME Desktop. DG Terrain Viewer works, too, for both Windows and Linux. You can also import an HGT file into Blender with the blender-osm addon.

Note: If you're using VTBuilder to open your HGT file, it's not done within the regular Open Project menu item. Instead, you must import the file into the program through the Layer > Import Data > Elevation menu.

See the Shuttle Radar Topography Mission homepage, hosted by the NASA Jet Propulsion Laboratory, for all the basics on SRTM data, which comes in HGT format. The data itself can be downloaded from the SRTM page hosted by the US Geological Survey.

There's also a great overview of SRTM and the data produced. The USGS website also has some more information in a PDF.

Tip: If you have an HGT file that you know isn't an SRTM Data file, or it doesn't work with any of the software you read about above, it could be that your specific HGT file is actually in an entirely different format. If so, use a text editor to open the file. Sometimes, there's identifiable text within the file that can help you understand what program was used to build the file, which should direct you to more information on the format.

If you find that a program on your computer does try to open the HGT file, but it's the wrong application or if you would rather have another installed program open these files, there are other ways to change those settings.

How to Convert an HGT File

VTBuilder can export an HGT file to a Binary Terrain (.BT) file. To do this, first import the HGT file (Layer > Import Data > Elevation) and then save it using the Layer > Save Layer As... option.

VTBuilder also supports exporting an HGT file to PNG, TIFF, and a number of other common, and not so common, image and data formats.

In ArcGIS Pro, with the HGT file already open in the program, you should be able to go to ​Export > Raster to Different Format to save the HGT file under a new format.

The other programs above can probably convert HGT files, too. This is normally done through an Export option or a Save As menu.