> From: Andrew Guertin [mailto:[email protected]] > Subject: Re: [Imports] Vermont Town boundaries from VCGI > > Interestingly, on the US- > Canada border, most of the nodes seem to be exactly the same--OSM has > them marked with survey point reference numbers, so this would make > sense--but shifted a few centimeters. Probably something to do with > projections.
The Canada-US border is defined by the IBC which considers their list of survey points and turning points to be public domain so me and another user have done some work at using their positions to update the OSM data. Their turning points are defined and accurate to within the limits of their NAD27->NAD83 conversion, plus the error between NAD83 and WGS84 which is minimal. Their survey points are accurate within the limits of good survey equipment. I don't know if the other user has gotten to where you're looking at, but if they have that could explain the closeness and reference numbers. And I believe both of us are Canadian, so we can call it the Canada-US border. :) _______________________________________________ Imports mailing list [email protected] http://lists.openstreetmap.org/listinfo/imports
