SNIG, run by Portugal's Directorate-General for Territory (DGT), is the national spatial data infrastructure. It coordinates and provides access to authoritative Portuguese geographic data: administrative boundaries, land use and land cover (COS), orthophotos, and topographic data.
Through SNIG and DGT services, these reference layers are available as downloads and OGC web services. It is the authoritative complement to the dados.gov.pt open data catalog for precise national cartography.