GDALPROJ

GDALPROJ refers to the integrated use of the Geospatial Data Abstraction Library (GDAL) with the PROJ cartographic projection library to manage coordinate reference systems (CRS) and perform spatial transformations. It describes the interoperability layer that enables reading, transforming, and writing geospatial data across raster and vector formats with correct projection handling.

In practice, GDALPROJ coordinates CRS definitions, datum shifts, and projection pipelines by delegating math and CRS parsing to PROJ while GDAL handles data access and data model translation. PROJ supplies the CRS database, transformation algorithms, and grid-based operations, while GDAL provides the I/O abstractions, metadata management, and format support. This separation allows robust reprojection, CRS querying, and axis order normalization within geospatial workflows.

Typical functionality enabled by the GDALPROJ integration includes reading and interpreting CRS information from data sources, performing coordinate transformations between different projections, and reprojecting datasets during operations such as warping, conversion, or spatial querying. The combination underpins common command-line and API workflows, including tools like gdalwarp and ogr2ogr, as well as programmatic access through GDAL’s C/C++ interfaces and language bindings.

Licensing for both projects is open-source and permissive, which supports wide adoption in desktop, server, and embedded geospatial applications. GDALPROJ is central to contemporary geospatial processing, enabling consistent CRS handling and transformation across diverse data formats and platforms. See also GDAL and PROJ for related libraries and documentation.