Map calibration with Google Earth. How good is it?

The following article shows that it can be rather good:

http://www.gps-practice-and-fun.com/map-calibration.html

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Andreas van Hooijdonk
http://www.gps-practice-and-fun.com

In sci.geo.satellite-nav Andreas van Hooijdonk <ahooijdz@scarletz.bez


I have used the same method to match a photo that had property boundaries
on it. I intended to proceed and calibrate the photo, but once I had a
few waypoints, I had no further need.

On the page there is a note:
"In September 2001, one week after the 9/11 attacks in the US, we found the
reservoir at the Mavrokolympos dam almost completely empty."

Is that merely chronological coincidence, or was the reservoir emptied
for some reason?

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Clarence A Dold - Hidden Valley Lake, CA, USA GPS: 38.8,-122.5

the

This was indeed chronological coincidence. That holiday in Cyprus was great,
but the panic at airports and in the whole aviation world spoiled a bit of
our pleasure. That is why we remember this date so well.

Andreas

You might want to avoid the edges of the hires images because they are most
likely to be off. Some points might have two sets of coordinates on the
Google Earth screen due to poor image splicing and/or orthorectification.

Examples:
The shift of the road at about 31° 59' 46.5"N, 110° 59' 42"W. At
51° 02' 32"N, 114° 04' 27'W, the Calgary train station is visible.
Just a little to the northeast it's visible again at
51° 02' 38"N, 110° 04' 11.4"W.
Note the shear of the river to the north, too.

Rich
Untie the return address to e-mail me.

most

Rich,

I played many many hours with Google Earth and had never seen such an
important error.

Something else that could be interesting for you and others: I have a very
large 24" screen. In the older versions of GE the extreme left and right
parts of the image were always of much lower quality. I would say that only
a square in the middle was right. In the latest version 4.0.1693.0 this is
corrected, but the Calgary train station and the river still seem to have
been struck by something unimaginable.

Best regards

Andreas