How high?

Ever need to know the altitude at a given location on the Earth?

Well, there are several free resources to the rescue:

EarthTools has a webservice that covers the US and Europe using the SRTM data. Given a latitude/longitude it returns the height above sea-level in feet and meters. (found from Quakr Viewr)

Geonames offers two services using the SRTM data, and also the GTOPO30 from the USGS. Geonames gets bonus points for also returning the results in JSON. Geonames also uses a larger dataset - lands within 60 degrees north and 56 degrees south.

As "points" become rather ubiquitous among neogeographers/web-mappers, they're moving into more complex geometries and especially 3D space. Having access to data means it is very easy to tie into services and applications. For example, making a hiking profile given just 2-d ground waypoints.

You can download the data yourself to do whatever you want with it. Perhaps make yourself a very cool, high-res 3D model of the earth.

It's not clear how accurate the data is. The reports seem to say within 9m vertical accuracy. But I assume this is measuring the "surface" that the Shuttle saw - so that would include roof tops. But with smoothing/filtering, would this be washed out to represent an average 'ground height'?

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About the Author

Andrew Turner is an advocate of open standards and open data. He is actively involved in many organizations developing and supporting open standards, including OpenStreetMap, Open Geospatial Consortium, Open Web Foundation, OSGeo, and the World Wide Web Consortium. He co-founded CrisisCommons, a community of volunteers that, in coordination with government agencies and disaster response groups, build technology tools to help people in need during and after a crisis such as an earthquake, tsunami, tornado, hurricane, flood, or wildfire.