Re: Offset threshold problem

Erik Hofman wrote:

> For what I've seen so far the STRM data incorporates terrain elevation 
> due to stables, farm houses, trees (or rather small woods), tall 
> buildings, etc.
>
> So in reality the data is too accurate for our needs.


Yes, when you start digging into this stuff it get's complicated quick.  
What we *want* is the elevation of the ground for the entire earth.  
What we get is radar reflections off of what's ever there ... often we 
can see evidence of objects in the data.  Are we getting the tops of 
trees or the bottom?  The further you dig into this stuff, the harder it 
get's.  With some sensors you might get a primary reflection off the top 
of trees, a secondary reflection of the lower level bushes and once in a 
while a 3rd refelection off the ground.  Now try to sort that out. :-)

Curt.

-- 
Curtis Olson        http://www.flightgear.org/~curt 
HumanFIRST Program  http://www.humanfirst.umn.edu/
FlightGear Project  http://www.flightgear.org
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