UTM projects a spherical globe onto a cylinder. Zones are chosen to achieve a certain level of accuracy of distances between points. This accuracy decreases as you stray from the zone, but is not too bad as long as you're not too far past the edges of the zone. "Too bad" and "too far" are inter-dependent and also depend on your uses of the data. If you need cm-size accuracy, you don't want to extend half-way into the next zone, for instance. There is a mathematical relationship between accuracy and distance from the central meridian of the zone.
Tim Glover Senior Environmental Scientist - Geochemistry Geoscience Department Atlanta Area MACTEC Engineering and Consulting, Inc. Kennesaw, Georgia, USA Office 770-421-3310 Fax 770-421-3486 Email [email protected] Web www.mactec.com -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Corrie Curtice Sent: Thursday, October 08, 2009 12:13 PM To: [email protected] Subject: [R-sig-Geo] location points that span UTM zones Hello, I have some location data points that span two UTM zones. I'm using the points to estimate home ranges, using a couple of home range tools (NNCH, HRT for ArcGIS). Can I just project them to the left most zone, and run the home range tools on that data set? I'm curious to know what the negative impacts of this might be. These are points around the west coast of Mexico, so UTM 12/13 and 13/14. Thanks, Corrie _______________________________________________ R-sig-Geo mailing list [email protected] https://stat.ethz.ch/mailman/listinfo/r-sig-geo _______________________________________________ R-sig-Geo mailing list [email protected] https://stat.ethz.ch/mailman/listinfo/r-sig-geo
