GRASS GIS — The Complete Guide: Free Advanced Spatial Analysis, Hydrology and Terrain
GRASS GIS is an open-source geographic information system, one of the oldest in the world, originally developed by the US Army and maintained today by OSGeo. Its strength is analysis — especially of rasters and terrain models — with hundreds of documented modules.
GRASS GIS
OSGeo
GIS with strong raster and terrain analysis — catchments, slope, visibility and elevation models.
Get it from the vendorEngineering uses
- Hydrology — flow direction, flow accumulation, watershed delineation and stream networks from an elevation model.
- Terrain — slope, aspect, contours and profiles.
- Visibility — what can be seen from a point, for antenna planning or visual impact.
- Remote sensing — satellite image classification and vegetation indices.
- Batch processing — every module is also available from Python.
How to use it
You can run GRASS as a standalone program, but the convenient route for most engineers is from QGIS: GRASS tools appear in the QGIS processing toolbox and run on the open layers. Similar tools exist in SAGA GIS and WhiteboxTools.
QGIS
QGIS.org
Open-source GIS for spatial analysis, layer work and map production.
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SAGA GIS
SAGA Development Team
Advanced spatial analysis, especially on elevation models and terrain.
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WhiteboxTools
Whitebox Geospatial
Hundreds of geospatial analysis tools, especially strong on terrain and LiDAR point clouds.
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HEC-HMS
US Army Corps of Engineers
Rainfall-runoff hydrological model — infiltration, unit hydrograph and routing. Pairs with HEC-RAS.
Get it from the vendorThe bottom line
GRASS GIS is a powerful, free spatial analysis engine. Most engineers will benefit from it through QGIS, without learning another interface.