ClearGeo Elevation Explorer

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Tip: click the map to sample elevation.

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Geocoding by Nominatim (OpenStreetMap). Please use responsibly.

Point

Latitude

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Longitude

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Elevation

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meters

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Click the map to query elevation.

Show all sources

Run all third-party providers (slower)

Sample at map center (debounced)

Providers

Controls apply to browser-side third-party calls. The same-origin API remains the preferred baseline.

Loading provider controls…

Server-side alternates + validation

Source

Method

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Dataset

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Resolution

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Vertical datum

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Vertical reference

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Vertical reference notes

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Estimated accuracy

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Links

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History

Recent sampled points (stored locally in your browser).

About

This tool prefers high-resolution LiDAR-derived DEMs when available. In this static-hosted version, elevation sampling uses a public elevation API as a reliable baseline, and the app is structured to add LiDAR/COG sampling later.

Data sources: USGS 3DEP / National Map elevation services; planned: USGS LiDAR public bucket (S3 listing).

What elevation means: Vertical reference basics · Data sources · Free web APIs · Use cases

API visibility: health · health+debug · sample+debug

API Status

Live readout from ./api/elevation.php?health=1.

API

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CORS

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Security headers

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What “elevation” means

An elevation number isn’t just “height.” It’s a height measured relative to a vertical reference (sometimes called a “vertical datum”). Different services can use different references, and those values may not be directly comparable.

Common vertical reference types

Orthometric height

Height above an approximation of mean sea level (gravity-based). In the U.S., engineering work often expects NAVD88. Many public APIs do not state this clearly.

Ellipsoidal height

Height above a mathematical ellipsoid (e.g., WGS84/ITRF). This can differ from NAVD88 by tens of meters. Converting between ellipsoidal and orthometric heights requires a geoid model.

Unknown / unspecified

If the upstream service doesn’t declare a vertical datum/geoid, treat the value as best-available for exploration and verify for any engineering deliverable.

Why two sources can disagree

Different DEM resolution: 1m LiDAR vs 10m vs 30–90m global DEMs.
Different surface definition: bare-earth (DTM) vs surface model (DSM with trees/buildings).
Different vertical reference: NAVD88 vs ellipsoidal vs unknown.
Interpolation and edge effects: nearest-pixel vs bilinear vs server-side smoothing.
Update cadence and coverage: datasets can be newer/older, or have gaps.

How to use this tool safely

Use Elevation Explorer for planning, field notes, and quick checks. For design/engineering, confirm elevations against authoritative project control and documented vertical metadata.

Data sources in this app

This app uses a two-phase strategy: (1) a same-origin API baseline (reliable, avoids CORS) and (2) optional third-party cross-checks (opt-in, best-effort).

Baseline (recommended)

Same-origin API: ./api/elevation.php (returns elevation + provenance + validation)
USGS EPQS (3DEP): U.S.-focused, generally the most trustworthy global-to-local baseline when LiDAR sampler isn’t available

Optional cross-checks (opt-in)

OpenTopoData: global DEM-backed point lookup (multiple datasets)
Open-Meteo elevation: global DEM-backed point lookup (easy batching)
Open-Elevation: community endpoint(s) (rate-limited; best-effort)
Elevation-API.eu: Copernicus-backed (rate-limited)
GeoNames SRTM3: requires free username (credit-limited)

Free web APIs & services (copy/paste)

These are additional free, web-accessible sources you can use in development. They fall into three buckets: (A) point elevation lookups, (B) raster/DEM extraction & catalogs, and (C) topo visualization tiles.

A) Point elevation lookup (lat/lon → elevation)

USGS EPQS (no key)

https://epqs.nationalmap.gov/v1/json?x={lon}&y={lat}&units=Meters&wkid=4326&includeDate=false

U.S. authoritative baseline (3DEP). Best for most U.S. use cases.
OpenTopoData (no key, rate-limited)

https://api.opentopodata.org/v1/{dataset}?locations={lat},{lon}|{lat},{lon}

Dataset list: opentopodata.org/#datasets
Open-Meteo elevation (no key)

https://api.open-meteo.com/v1/elevation?latitude={lat},{lat2}&longitude={lon},{lon2}

Easy batching (up to documented limits). Good for “many points” sampling.
Elevation-API.eu (no key, rate-limited)

https://www.elevation-api.eu/v1/elevation/{lat}/{lon}?json

Provider states Copernicus DEM sourcing; treat as best-effort and verify for engineering.
GeoNames SRTM3 (free username required)

https://api.geonames.org/srtm3JSON?lat={lat}&lng={lon}&username=YOUR_USERNAME

Credit-limited. Useful as a quick cross-check.
GMRT PointServer (global topo + bathymetry)

https://www.gmrt.org/services/PointServer?latitude={lat}&longitude={lon}&format=geojson

Great when you need land + seafloor context. Elevation can be negative offshore.

B) Raster/DEM extraction + discovery (not point lookup)

OpenTopography API (free key)

https://portal.opentopography.org/apidocs/

Programmatic DEM subsetting/download (SRTM, ALOS, Copernicus, USGS 3DEP, etc.).
Planetary Computer STAC (free)

https://planetarycomputer.microsoft.com/api/stac/v1

Search & read DEM COGs via STAC (e.g., Copernicus DEM collections). Use a STAC client (pystac-client) for automation.
USGS 3DEP Elevation ImageServer (ArcGIS REST)

https://elevation.nationalmap.gov/arcgis/rest/services/3DEPElevation/ImageServer

Scriptable raster service. Use /identify for point sampling or download methods for raster workflows.
GMRT GridServer (gridded extraction)

https://www.gmrt.org/services/GridServer

Programmatic gridded data subsets (up to large payload sizes; supports multiple formats).

C) Topographic tiles (visualization)

OpenTopoMap tiles

https://{a|b|c}.tile.opentopomap.org/{z}/{x}/{y}.png

Topo-looking basemap (not raw elevation). Community capacity: cache/self-host for heavy use.
USGS Topo basemap (ArcGIS REST)

https://basemap.nationalmap.gov/arcgis/rest/services/USGSTopo/MapServer

U.S. topographic reference map tiles/layers (visual). Not a DEM.
AWS Open Data terrain tiles (Terrarium)

https://s3.amazonaws.com/elevation-tiles-prod/terrarium/{z}/{x}/{y}.png

Encodes elevation in RGB (Terrarium). Great for web terrain/hillshade pipelines.

Tip: if you need help integrating any of these into your app, open the browser console and run a quick test:

fetch('https://epqs.nationalmap.gov/v1/json?x=-81.3031&y=29.0283&units=Meters&wkid=4326&includeDate=false').then(r=>r.json()).then(console.log)

Need deeper help? Vertical datum guide · Resources & catalogs · Troubleshooting · Use cases

ClearGeo Ecosystem

Related resources and system entry points: