RAS Commander Fast-Map

Native Rust 2D flood inundation mapping, distributed as the ras-commander-fast-map Rust crate and Python wheel. It maps computed hydraulic results; it does not run the HEC-RAS hydraulic solver.

Install

pip install ras-commander-fast-map
ras2fim-batch method

Python wheels provide the compatible ras2fim-batch executable on Windows x64 and Linux x64 (glibc 2.28+). A wheel requires no Rust compiler or system GDAL. Python consumers normally install ras-commander[fim], which adds the public RasFim APIs and Python preparation/GeoTIFF delivery dependencies. Remove the former ras2fim-engine package before installing this package if both would own the same executable. The command name and JSON contracts remain compatible.

Rust users can install the CLI or use the library independently of Python:

cargo install ras-commander-fast-map --locked
cargo add ras-commander-fast-map

let methods = ras_commander_fast_map::method_record();
assert!(methods.is_object());

See Rust API documentation and the RasFim guide for request contracts and end-to-end model preparation. The Rust library consumes prepared geometry, profiles and terrain; HDF extraction belongs to ras-commander-fast-hdf and Commander. The CLI does not read a plan HDF directly.

Methods and resource controls

• Horizontal: cell-constant WSE with native float32 visibility.
• Sloping: reconstructed cell corners; optional cell faces, depth weighting, and shallow-to-horizontal selection.
• ras2fim-2D Step05: the separate globally prepared SciPy triangulation method.

Terrain decoding and ownership rasterization use terrio with GDAL disabled. Rayon workers share immutable terrain/geometry across bounded in-flight profiles. Bbox/polygon output masks retain global hydraulic topology. Planned allocation admission is not a hard RSS limit. Python delivery may use Rasterio/GDAL; the Rust mapping executable does not link it.

Production methods and binary32 operation order are unchanged from the qualified Commander engine 0.8.0. MIGRATION.json binds the extracted source and immutable numerical files. Existing request schemas, method identifiers and CLI exit codes are preserved. ras2fim-batch method adds package/version/source-commit identity.

Qualification and limits

The retained five-model comparisons cover raw Depth/WSE validity masks and float32 bits against native HEC-RAS 7.0.1, without an added depth cutoff. Those published timing observations predate this packaging extraction; no new speedup is claimed for renaming/distribution.

Mapping covers physical 2D cells. Commander rejects models with 1D river/cross- section geometry. Standalone storage-area surfaces are excluded. Cell-face matching preserves the original source TIFF grid and 256-square tile layout; arbitrary retiled/cropped terrain and multi-source mosaics are unqualified. Depth weighting needs stored corner ground elevations. When absent, explicit corner preparation still uses Windows/HEC-RAS 7.0.1 through Commander and pythonnet; it has not been implemented in Rust. Once prepared, ordinary mapping runs on Windows/Linux without HEC-RAS. Source terrain must match the effective terrain used by the native reference.

Build and verify

cargo fmt --check
cargo test --locked --all-targets
cargo clippy --locked --all-targets -- -D warnings -A clippy::chunks_exact_to_as_chunks
cargo publish --locked --dry-run
python scripts/verify_sources.py

CI builds and smoke-tests Windows/Linux wheels. Tagged releases attach the wheels, source distribution, provenance and checksums to GitHub Releases. See release instructions for PyPI/crates.io publishing.

License and attribution

Our code retains its MIT license. Step05/SciPy reuse retains BSD-3-Clause notices; see LICENSE, THIRD_PARTY_NOTICES.md and licenses/. The crate license expression is MIT AND BSD-3-Clause. Dependency notices accompany distributions. HEC-RAS assemblies, decompiled vendor source and model data are not distributed. This independent project is not affiliated with or endorsed by HEC/USACE.