[UW-GIS-L] DNR Ortho vs. USGS Ortho accuracy

[Harvey Greenberg]

I have seen an occasional DNR orthos where the township line matches
a road centerline badly.  We have also seen mismatches up to 10'
in adjacent USGS orthophotos.  Aside from other problems, inaccuracies
of the DEM can cause substantial inaccuracies in the corners of a
wide-angle photo.

Are the DNR photos on the HARN datum?  I understand that arcGIS (I
don't know about version 9) has had trouble with HARN.

harvey

Derek Stuart wrote:
> Does anybody have any general comments regarding horizontal accuracy of
> orthophotos?
> 
> I have been comparing 1998 WADNR orthophotos with USGS orthophotos (Using
> ARCMAP 9) and there appears to be a 10' x and 10' y shift.  Is this a
> limit of the horizontal accuracy of the photos or is this simply a
> registration error?
> 
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	Harvey Greenberg
	University of Washington
	Department of Earth and Space Sciences
	Condon Hall (Box 351310)
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