ClubTread Community - View Single Post - negative elevation? (GPS question)

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post #13 of (permalink) Old 05-23-2008, 01:41 PM
magnetite
High on the Mountain Top
 
Join Date: Jan 2004
Location: North Vancouver, BC, Canada.
Interest: Mountain biking, hiking, nature photography, astronomy, music...
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Quote:
quote:Originally posted by ShadowChaser

Quote:
quote:Originally posted by OK Jack
With it set at NADS83 datum, it matches exactly the survey plans and the Google Earth info...
Google Earth uses WGS 84, not NAD 83.

Quote:
quote:
As Google Earth currently uses WGS84 datum projection, GIS files using NAD83 projection are not supported by Google Earth
Wrong, on several points. There is no such thing as a "datum projection". Datum and projection are separate things. Google Earth uses a cylindrical projection, and WGS84 datum. There is no such thing as a WGS84 projection.
The difference between NAD83 and WGS84 is approximately 50 centimetres. Considering that GPS error is typically 5 metres or higher, you can consider NAD83 and WGS84 to be the same. So, OK Jack is correct; setting your GPS to NAD83 will result in a match with Google Earth. MapSource will upload data into Google earth in WGS84 regardless of the datum you set your GPS to. In fact, regardless of the datum you used, it's always stored in WGS84 anyway.
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