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.
Open Navigation's Nav2 Complete Coverage is a ROS 2 application providing complete coverage path planning for agricultural and field operations. It integrates the Fields2Cover library with Nav2's behavior tree framework to compute optimal coverage paths from field polygons or pre-defined rows. The system consists of modular packages: coverage servers for open fields and row-based scenarios, message definitions, behavior tree nodes, a BT Navigator plugin, and demonstration tools. Key architectural features include a polymorphic route planner abstraction that unifies different routing algorithms, sophisticated coordinate transformation utilities, and lifecycle-compliant action servers that expose coverage planning as Nav2-compatible tasks. The application handles headland removal, field decomposition, swath generation, route ordering, and path generation with extensive configurability through action goals and dynamic parameters.