[aprssig] Android HUD Development
Stephen H. Smith
wa8lmf2 at aol.com
Fri Jun 10 00:37:03 EDT 2011
On 6/8/2011 3:37 PM, Arnie Shore wrote:
> I'm aware of the TIGER shapefiles; wd that be yr recommended source?
The TIGER files are terrible for real-time GPS applications. They are
intended for use by the US Census Bureau to account for every street in the US
for census-taking purposes, not for precision navigation.
In some rural areas, some roads and side roads are off by as much as a quarter
to a half mile or more, due either to roads being essentially "hand entered" in
their approximate location, or due to inconsistent datums. I.e locations
referenced to NAD 27 or other older datums weren't corrected to the WGS84 datum
used by GPS before being merged into the database.
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