[Talk-us] dubious church node

Mark Wagner mark+osm at carnildo.com
Sat Sep 30 17:05:56 UTC 2017


On Sat, 30 Sep 2017 15:11:06 +0700
Dave Swarthout <daveswarthout at gmail.com> wrote:

> "Second, many entries have their coordinates specified using the old
> NAD 27 datum, but somewhere along the line, that fact was lost and the
> coordinates were assumed to be in either NAD 83 or WGS 84.  This
> results in an offset that increases the further you go from central
> Indiana; the offset in Alaska is upwards of a hundred meters to the
> west."
> 
> Wow, thanks for that. If I understand what you're saying, this means
> many of the old GNIS nodes will be positioned about 100 meters east
> of where they should be? Or do I have your statement turned around?

Depending on where in the process the error was made, it could go
either way, but in my experience, the nodes are usually positioned too
far to the east.

-- 
Mark



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