Chris Metzler wrote:
OK, so to make sure I get it, I was incorrect about an FAA obstruction database being used; you do use the FCC ASR database. The correlation with tall buildings is simply because some (most?) tall buildings have antennae on the top. Is this right?
Yes.
If so, are their altitudes simply
set to ground level? Are the antenna heights used determined by the
height of building + antenna?
The FCC database reports ground level, elevation of the top of the tower, and height of the tower. Usually these are self consistant.
How reliable are the latlong coordinates in this database?
I have no idea. There does appear to be evidence of guessing and human error in the data.
I recently
modelled a 40-story building I wanted to put in its real-life location;
the latlong I'd dug up for the building didn't match any of the antenna
locations, so I didn't know what to substitute for.
You used to be online mapping services that would (directly or indirectly) get you the lat/lon of things on the image, but I think they realized the usefulness of this and I haven't found anything for free lately ... even mapquest seems to have gotten rid of their aerial photo feature.
If you live in the area you could drive over with a gps and survey the building yourself ... drive around the block a couple times and record the track? Gps's don't work well in down town environments because the satellites are often obstructured, but maybe you can get lucky enough to get a decent idea of the location.
What work have you already thought of that needs to be done? I'm trying to come up with scenery stuff to contribute these days; but I'm also interested in hearing about problems that need to be solved that don't involve lots of C++ coding (since I dunno how).
Presumably some of the work involves figuring out stuff like this:
http://www.speakeasy.org/~cmetzler/aerial_aerial.jpg
Yes. There are floating towers, there are extremely tall towers in the middle of some runway approaches, there are towers that have multiple antennas mounted to a single structure so you can have double towers on top of each other. It would be nice to calculate a FG ground elevation for each tower so none of them are blatently floating. There is a lot of sanity processing that needs to be done and perhaps some hand checking for blatent cases that interfere with runway approaches.
Regards,
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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