Sguaba is a Rust library that provides hard-to-misuse rigid body transforms (spatial math) for engineers. It enforces coordinate system safety at the type level using PhantomData and unsafe declarations, preventing accidental mixing of coordinate frames (e.g., NED vs FRD vs ENU). The library supports common Earth-bound systems (WGS84, ECEF) and local systems (NED, FRD, ENU), and provides both a mathematical API (Rotation, RigidBodyTransform) and an engineering-focused API (Orientation, Pose). It includes fast and extended algorithms for ECEF-WGS84 conversion based on recent research. The code is well-structured, thoroughly tested, and supports no_std environments via a libm feature. Active development with semantic versioning, comprehensive CI, and dependency management.
PROJ is a generic coordinate transformation library that converts coordinates between different coordinate reference systems (CRS). It includes a comprehensive catalog of map projections (over 190), datum shifts (grid-based, Helmert, TIN), and time-dependent deformation models. The library provides both a C API and a C++ ISO19111-compliant object model, along with command-line tools (proj, cs2cs, cct, projinfo, geod, gie, projsync). The architecture is a core transformation engine that dispatches through function pointers, with a pipeline system for chaining operations. The library relies on a bundled SQLite database (proj.db) containing EPSG definitions, and supports grid files for high-accuracy transformations. It is heavily used in geospatial software (e.g., GDAL, QGIS) and compiles on Linux, macOS, Windows, and WebAssembly through Emscripten.