Best HGT File Viewer Tools for Terrain and DEM AnalysisUnderstanding and working with HGT files is essential for anyone involved in terrain analysis, mapping, or digital elevation modeling (DEM). HGT is a common format used by the Shuttle Radar Topography Mission (SRTM) to store gridded elevation data. This article reviews the best HGT file viewer tools, explains how HGT files work, compares features, and provides practical workflows for visualization, analysis, and conversion.
What is an HGT file?
An HGT file stores a raster grid of elevation samples (height above sea level) for a 1°×1° geographic tile, typically generated by SRTM. Standard SRTM HGT tiles come in two main resolutions:
- SRTM-3 (3 arc-second) — ~90 m at the equator
- SRTM-1 (1 arc-second) — ~30 m at the equator
HGT files are usually raw binary signed 16-bit integers in big-endian byte order. Missing data values are often marked with -32768.
Key features to look for in an HGT viewer
- Support for native HGT (big-endian signed 16-bit) and automatic recognition of tile naming conventions (e.g., N37W122.hgt).
- Quick rendering and hillshading for immediate visual interpretation.
- Coordinate readout and ability to overlay basemaps (OSM, satellite imagery).
- Basic analysis tools: slope, aspect, elevation profile, contour generation, statistics.
- Export and conversion options to GeoTIFF, PNG, or common GIS formats.
- Batch processing for many tiles and command-line tooling for automation.
- Cross-platform availability and active maintenance.
Top HGT File Viewer Tools
Below are strong options, each with different strengths depending on your needs (quick viewing, advanced GIS analysis, or automated processing).
QGIS (Desktop GIS)
Why choose it:
- Full-featured open-source GIS supporting HGT, GeoTIFF, and many raster/vector formats.
- Powerful visualization: hillshade, color ramps, hillshading, blending with basemaps (XYZ/WMTS).
- Built-in raster analysis: slope, aspect, contour lines, zonal stats.
- Plugins extend functionality (e.g., profile tool, LAS tools, SRTM-specific helpers).
- Batch processing via the Graphical Modeler or Processing Toolbox; also supports Python (PyQGIS) for automation.
Use case example:
- Load multiple HGT tiles, merge with “Merge” tool, generate hillshade and contours, export to GeoTIFF for web maps.
GDAL (Command-line & Libraries)
Why choose it:
- The Swiss Army knife for raster and vector conversion and processing.
- gdal_translate to convert HGT to GeoTIFF; gdalwarp for reprojection; gdal_merge.py for mosaicking.
- gdalinfo for metadata and quick stats; gdal_calc.py for custom raster math.
- Works in scripts and pipelines; binds to Python, C/C++, and more.
Example commands:
# Convert HGT to GeoTIFF gdal_translate -of GTiff N37W122.hgt N37W122.tif # Create hillshade gdaldem hillshade N37W122.tif N37W122_hillshade.tif -z 1.0 -s 1.0 QField / OruxMaps / Mobile Apps (Field Viewing)
Why choose them:
- Lightweight mobile viewers for HGT/DEM overlays on maps while in the field.
- Useful for quick elevation checks, routing, and offline base layers.
- Some support custom raster tiles or GeoTIFFs derived from HGT conversion.
Limitations:
- Limited analysis compared to desktop GIS; best used for visualization and field navigation.
SAGA GIS
Why choose it:
- Fast raster processing tailored to terrain analysis: hydrology, watershed, topographic position index.
- Extensive terrain analysis modules (channel networks, catchment delineation, geomorphometry).
- Supports loading HGT via GDAL and performs batch operations.
Use case example:
- Extract drainage networks, perform flow accumulation, and classify landforms from HGT-derived DEMs.
Global Mapper
Why choose it:
- Commercial GIS with strong, easy-to-use DEM viewing and analysis features.
- Fast rendering of large DEMs, hillshading, contour generation, and watershed tools.
- Good for users who prefer GUI-driven workflows and need robust export options.
Limitations:
- Paid license for advanced features.
MicroDEM
Why choose it:
- Lightweight Windows application focused on DEM visualization and analysis.
- Quick hillshades, profiles, contouring, and basic terrain statistics.
- Freeware, good for quick inspections without heavy GIS setup.
Web-based Viewers (e.g., DEM Viewer services)
Why choose them:
- Fast, zero-install visualization of HGT-derived DEMs via browser.
- Useful for sharing and quick checks; some support hillshades, overlays, and profile extraction.
Limitations:
- Privacy and data size constraints; not ideal for heavy analysis or large mosaics.
Comparison Table
| Tool | Native HGT Support | Terrain Analysis | Batch/CLI | Ease of Use | Cost |
|---|---|---|---|---|---|
| QGIS | Yes | Advanced | Yes (Processing/PyQGIS) | Moderate | Free |
| GDAL | Yes | Via tools | Excellent | Low (CLI) | Free |
| SAGA GIS | Yes (via GDAL) | Advanced (terrain) | Yes | Moderate | Free |
| Global Mapper | Yes | Advanced | Yes | High (GUI) | Paid |
| MicroDEM | Yes | Basic-Moderate | Limited | High (simple GUI) | Free |
| Mobile apps | Some | Basic | No | High | Mostly Free/Paid |
Practical workflows
-
Quick visual check (single tile)
- Use MicroDEM or QGIS to open the HGT file, apply a color ramp and hillshade, inspect elevation at points.
-
Convert and prepare for web maps
- gdal_translate to GeoTIFF → gdalwarp to reproject (e.g., to Web Mercator) → generate tiles with gdal2tiles.
-
Large-area analysis (mosaicking many tiles)
- gdal_merge or GDAL VRT to combine tiles → create hillshade and slope maps → import into QGIS or SAGA for advanced processing.
-
Hydrology and watershed modeling
- Use SAGA or QGIS (with GRASS/SAGA toolboxes) to fill sinks, compute flow direction/accumulation, and extract stream networks.
Tips and pitfalls
- Check byte order and format: HGT is big-endian 16-bit signed integers; misinterpreting endianness produces garbage.
- Handle voids (-32768) before analysis: fill with interpolation or use void-filled SRTM products.
- Watch projection: HGT tiles are in geographic coordinates (WGS84). Reproject before combining with projected datasets.
- Pay attention to resolution differences when mixing SRTM-1 and SRTM-3 tiles.
Conclusion
For most users, QGIS plus GDAL forms the most flexible and cost-effective HGT workflow: GDAL for conversion/automation and QGIS for visualization and interactive analysis. For specialized terrain analytics, SAGA GIS or commercial tools like Global Mapper provide powerful modules. For quick checks, MicroDEM or web/mobile viewers are fast and convenient.
If you want, I can: provide step-by-step commands to convert and visualize a specific HGT tile, generate sample hillshade and slope maps, or create a small Python script to batch-convert a folder of HGT files.
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