[TowerTalk] terrain profile algorithm
jimlux at earthlink.net
Sat Jun 16 06:21:22 PDT 2012
I'm looking for an algorithm for my "generate all profiles for HFTA" app..
I've taken a couple trivial shots at this, but I'm pretty sure someone
out there knows of a "better way".
here's what I want..
I have an array of heights vs distance at fairly close post spacings (on
the order of 10 meters) maybe 1000 points or so, representing the
profile along a particular radial. What I want to do is "compress" that
into about 100 or so segments that are connected (e.g. HFTA input).
That is, I want to convert that to a series of x,y coordinates connected
by straight lines that "adequately" represents the terrain.
I started with a simple "if the adjacent point is within X meters in
altitude, then collapse the two into one", but that produces profiles
that somehow don't look right (and I can't say much about their HFTA
fidelity). If the underlying terrain were a ziggurat or mesas with
valleys, it would probably work, but it turns a gentle slope into a
This is a classic problem in cartographic generalization, and, as it
happens, this kind of profile is well represented by a fractal, but not
that this helps me much. I was hoping that someone out there knew of a
clever way to do it.
Preferably in Python, since that's what I've written everything else in,
but I can convert anything.. so if you have one written in COBOL, that's
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