The new elevation data is a fine feature but for some reason that I
don't understand no one seems to want to say what the source of the
data is or what the resolution of the data is. See my own unanswered
post here
http://groups.google.com/group/google-maps-js-api-v3/browse_thread/thread/14e6c6b8f40c6fa4/dd03ea55da41af58#dd03ea55da41af58
and the same unanswered question from ibgpsn here
http://groups.google.com/group/google-maps-js-api-v3/browse_thread/thread/a9bab8ca2e4d63d/daa4b0dbe03a1353?lnk=gst&q=elevation#daa4b0dbe03a1353

I have written a short script that compares the two datasets which can
be accessed here 
http://members.chello.at/stephen.joung/indexGoogleHeights_v3_2.html

You can enter coordinates or simply click on the map to set two ends
of a profile. The elevation of these two markers is then given using
the Google elevation data and the SRTM3 elevation data and a profile
is shown indicating the heights between these two markers from both
the Google ldata and the SRTM3 data. The profile data is called every
100m from the start marker for both datasets.

The SRTM3 data offers a resolution of  3arc-seconds (about 90m) and I
hope this comparison site will be useful to anyone that needs to check
the accuracy of the Google Elevation Data. It would still be nice for
us to be told the source and resolution of the Google Elevation Data.

BTW, SRTM3 shows sea level as 0m but Google data includes undersea
elevations.

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