What Is an HGT File?

How to open and convert SRTM data files

What to Know

  • An HGT file is a Shuttle Radar Topography Mission (SRTM) Data file.
  • Open one with VTBuilder or DG Terrain Viewer.
  • Convert to BT or PNG with VTBuilder.

This article explains what an HGT file is and how it's used, plus how to open one on your computer and how to convert one to a different format.

HGT is also short for Honeywell Gas Technologies, but that has nothing to do with the file format explained on this page.

What Is an HGT File?

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 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 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.

HGT file open in VTBuilder
An HGT File in VTBuilder.

See Shuttle Radar Topography Mission, hosted by the NASA Jet Propulsion Laboratory, for all the basics on SRTM data, which comes in HGT format. There's also this great overview of SRTM and the data produced.

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 it into Blender with the blender-osm addon.

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.

If you find that a program on your computer does try to open the HGT file but it's the wrong application or you'd rather have another installed program open these files, learn how to change those settings in Windows.

How to Convert an HGT File

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

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

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

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

Still Can't Open It?

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 file is actually in an entirely different format.

If so, use a text editor to open it. Sometimes, there's identifiable text within the file that can help you understand what program was used to build it, which should direct you to more information on the format.

If not, maybe you're misreading the file extension, confusing an SRT file for an HGT file. HTG is another example that appears related, but is actually used by HackTheGame for mission pack files.

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