[Xastir] 2004 Tiger Files

[Gerry Creager N5JXS]

OK.  Thought for the day.  Comparing TIGER files against the 2003/2003 
version isn't a good check based on some of the research I've done.  In 
fact, TIGER is probably *not* a good datasource, as those files are 
taken from USGS SDTS (although that's not what Cesus claims, but that's 
another story), and munged to accommodate the needs of Census. 
Technically, they shouldn't be releasing the munged dataset claiming it 
meets National Map Accruacy Standards, as their changes take nominally 
good data and redefine it based on data that are interpolated from a 
variety of sources, including hand-written notes and mileage estimates 
from folks' cars.

So: The short form is Caveat Cartographer.  Be careful with that data.

A better comparison, and one I intend to do locally, is to drive the 
area and see where the GPS points lie.  The common GPS accuracy today 
lies between 6-10 meters horizontal, and thus is better than the 
accuracy of the TIGER maps at their base.  If reality (via GPS) is 
consistent with TIGER, the maps are OK.  Verifying maps against maps 
with known problems isn't verification.

Pedantically academically yours,
Gerry

Reuven Z Gevaryahu wrote:
> Derrick J Brashear wrote:
> 
> 
>>The batch is running reliably at this point, and I think I can rerun the
>>whole country in maybe 8 hours. Someone want to check a sample
>>http://www.dementia.org/~shadow/www/PA_Allegheny_County.zip and see if
>>it looks right?
> 
> 
> (You need to take the "/www" out of that link)
> 
> The file looks fine as compared to the 2003 version of the file and
> terraserver.
> 
> --Reuven (KB3EHW)
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