On Sat, Feb 6, 2010 at 9:37 PM, Donald Campbell II <[email protected]> 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. > Or... > 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 non-trivial. 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. http://www.indiebound.org/book/9780122861666 But a mapping code library will convey this received wisdom more efficiently. -- Bill [email protected] [email protected] _______________________________________________ newbies mailing list [email protected] http://lists.openstreetmap.org/listinfo/newbies
