Resources & catalogs for elevation inquiry

Use this page when you need to go deeper than point lookups: discovering datasets, pulling DEM subsets, validating provenance, or building your own sampler.

Fast starting points

• USGS EPQS docs: https://nationalmap.gov/epqs/
• USGS 3DEP overview: https://www.usgs.gov/3d-elevation-program
• OpenTopoData datasets: https://www.opentopodata.org/#datasets
• OpenTopography API docs (free key): https://portal.opentopography.org/apidocs/

STAC (dataset discovery at scale)

STAC is a standard for discovering geospatial datasets (often Cloud-Optimized GeoTIFFs). It’s one of the most scalable ways to find DEM sources programmatically.

• Planetary Computer STAC (free)
  https://planetarycomputer.microsoft.com/api/stac/v1
  Use for Copernicus DEM collections, USGS elevation products, and more.

USGS raster services (ArcGIS REST)

• 3DEP Elevation ImageServer
  https://elevation.nationalmap.gov/arcgis/rest/services/3DEPElevation/ImageServer
  Useful for point sampling (/identify) and raster workflows depending on endpoints/limits.

Bathymetry + topo synthesis (global)

• GMRT services directory
  https://www.gmrt.org/services/
  PointServer (point samples), GridServer (subsets), ProfileServer (profiles).

Build-your-own sampler guidance (conceptual)

• When you outgrow public APIs: build a server-side sampler (COG/GeoTIFF pixel reads) with a footprint index.
• Recommended pattern: index DEM extents in SQLite + RTree → choose best raster → sample pixel → return value + provenance.
• Operational key: always return the vertical reference metadata you used (datum/geoid), not just the number.