On 10/23/2010 10:46 AM, Mike Thompson wrote:
I can't speak in regards to the horizontal error, but in regards to
the vertical error, GNIS elevation is taken from the National
Elevation Dataset (NED). The NED is a gridded dataset (30 meter
posting I believe), and does not contain spot heights, which is what
you want. In other words, the NED contains the *average* elevation
for each grid cell, not the peak elevation.
Mike
So it looks like NPS would be more accurate for vertical. On the other
hand I looked at NAIP imagery which is quite well aligned if I trust the
road tracks I took. On that one GNIS seems to be closer to the ridge
than NPS.
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