#398566 - 04/23/06 11:06 PM
Elevation data?
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New Poster
Registered: 04/23/06
Posts: 1
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Salaam.
Does anyone know the source and accuracy of the elevation data within Google Earth? I want to try and use them to make corrections to some gravity data I collected in the UAE. Is it possible to download the elevation data?
Thanks,
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#398567 - 04/23/06 11:26 PM
Re: Elevation data?
[Re: jsmall]
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Master Chronicler
Registered: 12/09/02
Posts: 3112
Loc: Northern California
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The global terrain dataset is 90M SRTM.
_________________________
Be seeing you,
Seer
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#398568 - 04/26/06 06:01 AM
Re: Elevation data?
[Re: seer]
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Guide
Registered: 07/30/05
Posts: 597
Loc: Wales, Europe
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Quote:
The global terrain dataset is 90M SRTM.
Is that authoritative? I'm not questioning that you are right, but have up-to now only seen it as a rumour, but nobody has been able to confirm. Also IIRC it appears slightly tidier than SRTM in places so possibly its been slightly processed?
As to the original question, no its not exportable from GE, but you can get it elsewhere, for a smallish number of points its probably easiest to use a web-service like here.
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#398570 - 04/26/06 01:37 PM
Re: Elevation data?
[Re: barryhunter]
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Guide
Registered: 09/19/05
Posts: 456
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Quote:
Also IIRC it appears slightly tidier than SRTM in places so possibly its been slightly processed?
I can take the same SRTM data and depending on what algorithm I use to interpolate between the data points, it can look completely different upon rendering.
Imagine sampling a sinusoid at the Nyquist frequency. Now take that data and do a linear interpolation on it. It will just be a zig-zag sawtooth looking function. Now interpolate using a nearest neighbor approach, and the interpolating function looks completely different--more like a square wave. You can imagine that certain peicewise smooth polynomial interpolation schemes would recover the original sinusoid fairly well if the derivatives are matched across the intervals though.
Edited by HookEmHorns (04/26/06 01:39 PM)
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#398571 - 04/26/06 05:01 PM
Re: Elevation data?
[Re: seer]
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Traveler
Registered: 03/15/06
Posts: 76
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Quote:
The global terrain dataset is 90M SRTM.
Thank you for verifing the source of the underlying elevation data in GE.
Given a 90m grid, the errors in the terrain that I see in my area of interest are well within expectations:)
BTW is there any way to substitute higher 'resolution' elevation data in local areas, similar to an overlay?
Thanks again - asxless in iLand
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#398572 - 05/05/06 03:59 AM
Re: Elevation data?
[Re: Chief_Sparky]
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New Poster
Registered: 05/05/06
Posts: 1
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Is there anywhere to get certified info on GE, such as DTM, ellipsoid used, spatial resolutions, accuracy of positions. Im doing a thesis and I need this info.
thanks
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