The National Geospatial-Intelligence Agency (NGA) is an unusual entry on this page — it's a U.S. Department of Defense combat support agency whose primary mission is geospatial intelligence for national security, but whose publicly released products include some of the most precise topographic, geodetic, and navigational data available from any single source.
NGA collaborated with NASA on SRTM — the global elevation dataset that underpins countless civilian GIS workflows — and maintains the World Magnetic Model used for compass calibration in every GPS device and smartphone on Earth. For GIS professionals, NGA's open products represent military-grade precision applied to foundational geographic data.
The publicly available datasets are narrower in scope than what agencies like USGS or NASA offer, but they fill specific niches that other sources don't cover as well. The GeoNames database provides standardized feature names with coordinates for locations worldwide — a geocoding resource for international projects. Digital nautical charts and aeronautical products serve maritime and aviation navigation at a level of detail that civilian alternatives rarely match.
The elevation products, topographic maps, and geodetic reference data serve as authoritative baselines for terrain analysis, positioning, and 3D mapping. The key limitation is that many NGA products remain restricted to authorized users, so the publicly accessible catalog represents only a fraction of what the agency produces — but that fraction includes foundational datasets that the broader geospatial community depends on.
