[towerguy3]

Using GoogleEarth I find that the elevation over open water (not a lake) is not always 0 ft. You can run the Cursor around in Full Screen mode and see the elevation of a point that the cursor points to at screen bottom.

For example a short distance around Vancouver harbour the sea level elevation reads 40 - 70 ft. Should sea level not be at exactly 0 ft? Is GoogleEarth measuring underwater formations?

How does GoogleEarth accurately give elevations? Is the data stored for every point (Lat. and Long.) on the Earth or is it an automatic measurement via satellite?

Another curious point. When I point the cursor onto the roof of a 600 ft high building, I don't get the elevation of that roof as being 600 ft higher than the surrounding sidewalk. Is this an averaging technique?

[ReginaGuy]

Using GoogleEarth I find that the elevation over open water (not a lake) is not always 0 ft. You can run the Cursor around in Full Screen mode and see the elevation of a point that the cursor points to at screen bottom.

For example a short distance around Vancouver harbour the sea level elevation reads 40 - 70 ft. Should sea level not be at exactly 0 ft? Is GoogleEarth measuring underwater formations?

That's just because Google Earth's elevations aren't perfect, and the elevation "resolution" isn't that great, so 40ft is probably the elevation of the adjasent land.

How does GoogleEarth accurately give elevations? Is the data stored for every point (Lat. and Long.) on the Earth or is it an automatic measurement via satellite?
I'm not sure of the exact method they use to get the ground elevation, but I'd be willing to be its from satelites, because Google Earth will still show you mountains on a remote uninhabited island in the middle of nowhere, which I doubt has ever been surveyed.

Another curious point. When I point the cursor onto the roof of a 600 ft high building, I don't get the elevation of that roof as being 600 ft higher than the surrounding sidewalk. Is this an averaging technique?

Once again, thats just because the resolution of the ground elevations is very low, so yes, its due to averaging