Open HGT Files Online Free - View NASA SRTM Data
Quick context: HGT files are a common format for storing digital elevation models (DEMs), specifically those generated by the NASA Shuttle Radar Topography Mission (SRTM). These files contain elevation data in a grid, typically with one arc-second (about 30 meters) or three arc-second (about 90 meters) resolution. They represent ground elevation above sea level, making them crucial for geographic information systems (GIS) and various mapping applications.
Technical Structure
An HGT file's structure is fairly straightforward for a binary format. Each file covers a specific geographic area, typically a 1-degree by 1-degree latitude/longitude cell. The filename itself indicates this coverage, for example, N34W118.hgt would cover the area from 34 to 35 degrees North latitude and 118 to 119 degrees West longitude. Inside, it's a grid of 16-bit signed integers representing elevation in meters, relative to the WGS84 EGM96 geoid. The data is stored in row-major order, meaning row by row, from north to south, then west to east within each row. The order of bytes for each 16-bit integer is big-endian. This fixed structure makes them relatively easy to parse directly, assuming you know the file's resolution (1-arc-second files are 3601x3601 data points, 3-arc-second are 1201x1201). These specific grid dimensions are because each degree cell includes the boundary points for seamless tiling, so a 1-degree cell with 1-arc-second resolution has 3600 intervals + 1 boundary point, resulting in 3601 points.
How to Open HGT Files
To open HGT files, you'll generally need specialized GIS software. Popular options include QGIS, ArcGIS, or GRASS GIS. Many of these tools allow you to simply drag and drop the HGT file, and it will recognize the spatial reference and display the elevation data as a raster image. If you're looking for a quick online solution to [open HGT files](https://openanyfile.app/hgt-file), OpenAnyFile.app provides a convenient way to visualize these datasets without needing to install dedicated software. For programmatic access, libraries in Python (like GDAL) or Java can read this binary data directly and convert it into a usable array for further processing or visualization. Simply put, you just need a tool that understands what a [DEM format](https://openanyfile.app/format/dem) is and how to interpret its headerless structure based on the filename. If you need to understand [how to open HGT](https://openanyfile.app/how-to-open-hgt-file) files, our platform offers a guided approach.
Compatibility and Problems
HGT files are widely compatible within the GIS ecosystem as they adhere to a well-documented standard established by NASA. Most GIS software and libraries can read them without issues. The primary "problem" users encounter isn't compatibility per se, but rather the raw, unprojected nature of the data. They don't contain projection information or metadata directly within the file; this is inferred from the filename and the SRTM specification. If you rename an HGT file, GIS software might struggle to correctly place it geographically. Another consideration is the file size; while not massive, a single 1-arc-second file (3601x3601 points) can be around 25MB, which can add up if you're dealing with large areas. For conversions, you might want to [convert HGT files](https://openanyfile.app/convert/hgt) to more broadly supported image formats. For instance, converting [HGT to TIFF](https://openanyfile.app/convert/hgt-to-tiff) or [HGT to PNG](https://openanyCfile.app/convert/hgt-to-png) allows for easier integration into standard image processing workflows, though you'll lose the direct elevation value if not handled carefully (e.g., storing elevation in pixel values). Other common [GIS files](https://openanyfile.app/gis-file-types) like GeoTIFF often embed all necessary metadata, which HGT files don't.
Alternatives
While HGT files are a solid choice for global elevation data, several alternatives exist, often offering different resolutions, coverages, or bundled metadata. GeoTIFF is arguably the most common alternative for raster DEMs, as it's a flexible format that can store elevation data along with full georeferencing information in a single file. Other formats like ASCII Grid (.ASC) or binary floating-point grids can also store DEMs, though they might be less universally supported than HGT or GeoTIFF. For more niche applications, formats like the [KEYHOLE format](https://openanyfile.app/format/keyhole) for Google Earth or even newer data structures like [GeoJSON-LD format](https://openanyfile.app/format/geojson-ld) might be considered, though these focus more on vector geometry rather than raster elevation grids. The choice usually depends on the required resolution, the extent of the area, and the software you're using. Our platform lists [all supported formats](https://openanyfile.app/formats) for comprehensive reference.
FAQ
Q: What resolution do HGT files typically provide?
A: HGT files are commonly found in two resolutions: 1-arc-second (approximately 30 meters at the equator) or 3-arc-second (approximately 90 meters). The higher resolution files are more suitable for detailed local analyses.
Q: Can I use HGT files in standard image editing software?
A: Not directly. HGT files are binary elevation data, not image files. You would first need to convert them to an image format like TIFF or PNG, perhaps colorizing the elevation values, before they could be opened in software like Photoshop.
Q: Is there any projection information within an HGT file?
A: No, HGT files are raw elevation data with no embedded projection information. The geographic location and coordinate system (WGS84 latitude/longitude) are inferred from the filename and the SRTM data specification. Software reading HGT files must apply this context.
Q: What's the main limitation of HGT files compared to GeoTIFF for elevation data?
A: The primary limitation is the lack of embedded metadata, particularly projection information, which GeoTIFF includes. This means HGT files rely on external conventions (like their filename) for proper georeferencing, while GeoTIFFs are self-describing in that regard.