A remarkable share of the world’s geospatial foundation is free: Landsat and Sentinel imagery archives, near-global elevation models, OpenStreetMap’s crowd-built vector map, administrative boundaries, climate reanalyses and a growing family of AI-derived layers such as global building footprints. Knowing these sources — and their licences and limitations — is basic literacy; entire products and national programmes stand on them.
The imagery and elevation pillars
Earth observation: Landsat (five decades, 30 m) and Sentinel-1/2 (radar and 10 m optical, days-scale revisit) anchor free imagery, accessible through open portals and cloud platforms. Elevation: SRTM and Copernicus GLO-30 provide ~30 m global terrain; national LiDAR programmes (like the US 3DEP) publish far finer where they exist.
Each carries fitness bounds — resolution, acquisition dates, known artefacts — that responsible use respects and documents.
Vectors, boundaries and derived layers
OpenStreetMap is the planet’s most complete open vector map — roads, buildings, POIs — with quality that varies by community activity and an ODbL licence whose share-alike terms products must honour. Administrative boundaries (GADM, national portals), census and statistical layers, and open address efforts round out the vectors.
A new generation of derived datasets — global building footprints from satellite AI, land-cover maps like ESA WorldCover, population grids like WorldPop — supplies analysis-ready layers where official data is thin.
Using open data professionally
Open does not mean uniform: professional use validates quality in the study area, records versions and access dates, honours licences (attribution, share-alike), and blends open foundations with commercial or field data where accuracy demands. The economic pattern is consistent — open data for breadth, targeted paid data for depth.
Data-source fluency is itself a service: knowing what exists, what it is good for, and where it will quietly betray you.
Frequently asked questions
Is OpenStreetMap data reliable enough for professional use?
Often — in well-mapped regions its road and building coverage rivals commercial data — but quality is uneven and undocumented locally. Professional practice validates against imagery or field checks in the area of interest, and respects the ODbL licence.
Where can I get free elevation data for any country?
Copernicus GLO-30 and SRTM provide ~30 m DEMs with near-global coverage; many countries additionally publish national LiDAR terrain openly. For engineering-grade needs, commissioned LiDAR remains the standard.
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