On Tue, 01 Sep 2009 20:20:41 +0200 Christian Willmes <[email protected]> wrote: > Maybe I don't understand what you talking about the necessity to use > local coordinate systems, so can one please clarify to me, why one > can't (or should not) model - as precisely as you just want - every > single (not moving) point on earth in a Geocentric Spatial Reference > Frame [1]?
I'm not following this thread as closely as I should be, but another good reason to use local coordinate systems is that sometimes you know where points are relative to some local reference, but you don't know where that reference is very precisely in global terms. For instance, take a picture of something, there may be ways that you can pull information out of that picture with millimeter precision, but if you used a consumer GPS device to log where that picture was taken from, then the accuracy you get is good to ten meters or so. Dan _______________________________________________ Geowanking mailing list [email protected] http://geowanking.org/mailman/listinfo/geowanking_geowanking.org
