[OSM-newbies] Standard gps bounds notation?
bill.n1vux at gmail.com
Sun Feb 7 03:44:47 GMT 2010
On Sat, Feb 6, 2010 at 9:37 PM, Donald Campbell II
<donaciano2000 at gmail.com> wrote:
> at1 lat2 lon1 lon2
> but perhaps
> lat1 lon1 lat2 lon2
> is preferred?
frequently. that is both a list of two corner points or a tour around
the four sides.
> lon1 lat1 lon2 lat2?
those who rigidly think x y sometimes prefer that
> Maybe there's 2 or 3 common orderings and they have specific names so you
> know which you're dealing with?
i haven't run across names either.
> Also, as it stands I'm only using a rectangular bounds since it's easy to
> check if a point is inside it with a simple lat1 <= newpoint <= lat2
well, pseudo rectangles in spherical coordinates.
luckily the longitude wrap-around occurs mostly in wet territory so
you won't often if ever want to include lon +-180 or either pole
inside your box.
> but I should really use a better way of checking so that skewed boxes or
> arbitrary shapes could be used. Does anyone know where I could find an
> example of how to do that? There's probably a library that does this
> already somewhere.
Only worth doing if you get a library, as doing this right and fast is
Much skull sweat expended in 20thC computer graphics and mapping
research to get it right. The Graphics Gems series of books contains
much of this knowledge.
But a mapping code library will convey this received wisdom more efficiently.
n1vux at arrl.net bill.n1vux at gmail.com
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