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SurtGIS

High-performance geospatial analysis in Rust. A single CLI binary and a set of Rust crates that compute 127 terrain, hydrology, imagery, morphology, interpolation, and classification algorithms — with native GeoTIFF I/O, streaming for rasters larger than RAM, native CRS reprojection, and an end-to-end STAC composite pipeline for Planetary Computer and Earth Search. 56 of the 127 algorithms also compile to WebAssembly and run in any modern browser without a server, including the complete Florinsky 14-curvature morphometric system.

This book is the user guide. For the auto-generated API reference (for embedding SurtGIS as a library in Rust code), see docs.rs/surtgis-core.

What this book is for

If you’re looking for:

  • “Does this fit my workflow?” → start with Installation then the First terrain analysis tutorial. 30 minutes and you’ll know.
  • “How do I do X?” → How-to guides are task-focused and short. Pick the one that matches your problem.
  • “What flags does surtgis terrain slope take?” → CLI reference.
  • “Why does SurtGIS do it this way?” → Explanation covers architecture, memory model, and side-by-side comparisons with GDAL, GRASS, and WhiteboxTools.

The four sections don’t overlap by design. Tutorials teach. How-to guides solve. Reference is authoritative. Explanation reasons. This is the Diátaxis framework.

Design principles

  1. Native I/O, no GDAL required. GeoTIFF read/write including predictor 1/2/3, DEFLATE, GDAL_NODATA, and Cloud Optimized (COG) over HTTP range requests. GDAL is available as an optional feature.

  2. Streaming over in-memory when data grows. Algorithms that fit the strip-processing pattern (Horn slope, Gaussian smoothing, flow direction, fill-sinks, and about ten more) run with bounded RAM regardless of raster size. Detection is automatic; a --streaming flag forces the path when you want to be sure.

  3. One binary per platform. The CLI is statically-linked where possible. The default feature set for the precompiled binary covers STAC + COG + climate data (Zarr) + UTM reprojection. System-library dependencies (libnetcdf, HDF5) are opt-in via --all-features when building from source.

  4. Validated against the canonical alternatives. Slope, aspect, hillshade, flow accumulation, and watershed outputs agree with GDAL 3.11, GRASS 8.3, and WhiteboxTools within documented tolerances. The cross-validation numbers live in the paper (Environmental Modelling & Software, under review).

  5. Honest about tradeoffs. SurtGIS is not faster than everything at everything — see When to use SurtGIS vs alternatives for where the Rust reimplementation wins (I/O pipelines, parallel terrain factors, streaming) and where you’re better off reaching for GDAL or GRASS.

Current status

As of v0.8.1, SurtGIS has been used end-to-end on a 15-watershed Chilean landslide-susceptibility pipeline (Sentinel-2 composites, 41 M-cell areas, 60 labelled wells). The accompanying paper is in major-revision at Environmental Modelling & Software. Recent releases focused on: v0.7.5 fixed a critical decoder bug for Planetary Computer COGs with BitsPerSample=15 packed encoding; v0.7.4 added the native reproject command, removing the last dependency on gdalwarp; v0.8.x roughly doubled the WebAssembly surface, from 33 to 56 algorithms.

No external users are known yet — feedback from people outside the original developer/postdoc loop is exactly what would take this from “works for one expert” to “works for a community”. If that’s you, please open an issue or try the live demo — it runs the 56 WebAssembly algorithms client-side, so your DEM never leaves your machine.