Philmont KML file for Google Earth - improved coordinates


Date: Tue, 22 Aug 2006 13:59:29 -0700 (PDT)
From: Carl T Osborn
Subject: Philmont KML file for Google Earth - improved coordinates

This last weekend I found the time to pull coordinates from the 2005-06 Philmont maps prepared by the Philmont GIS Department. It's my understanding that these maps are based on actual on-the-ground GPS- location of Philmont assets by the GIS Department and represent the most accurate positional information to date. After scanning, I brought the maps into ExpertGPS, georeferenced the images to the UTM-NAD83 grid printed on the maps, digitized the locations of current camps, features, etc, and then output the coordinate information in decimal latitude and longitude in the WGS-84 datum. The same process could have been done manually with a UTM roamer applied directly to the maps, but doing it by computer was faster, and less prone to error.

I had gone through the same process several years ago with the old Philmont wall map. With the exception of just a few camps, I found that the positions on the old map were "off", in some cases by a significant amount compared with the postions from the new 2005-06 maps. Ute Gulch Commissary was one of the locations that was pretty inaccurate on the old map. There was no consistent pattern in the positional errors contained on the old map. [...]

Tim Osborn


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