Tuesday, December 9, 2008

New Circle Center Coordinates

I totally forgot about map datums! I had taken the latitude and longitude off the USGS topographical map, which is based on 1927 North American Datum. So, converted to the WGS 84 datum (which is what Google Earth uses), the current latitude and longitude are 31.470006° N, 111.172780°W.

The change in coordinates only affects the circle image I sent out as a .kmz file, moving it some 50 yards to the west. Not a huge difference. The circle as shown in blue on the topo map printouts is correct, as I used Photoshop Elements to draw the circle based on the topo map scale and the actual center ("Center of Section 36 of T 22 S, R 11 E").

Google Earth is a free program you can download to view the earth via satellite photos. It's like an animated version of Google Maps (which uses a simple web browser). If you click the bottom most option in the left column, change your angle with the up arrow on the dial in the upper left part of the screen, then zoom in, it's truly amazing. It's like being able to fly over the terrain.

Download it at Google Earth.

1 comment:

Andrew said...

If you would like to view the count circle in Google Maps (I like the terrain feature, which is for some reason lacking in Google Earth),

click here

url: http://tinyurl.com/atascosa