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copied!<p>You could at least rule out a large number of candidates with a naive box check in map coordinate space. There are probably three main cases here. Either there's a pole is in the rectangle or there isn't. If the pole isn't visible, either the rectangle crosses the +/-180 degrees line or not. There can't be any +/-90 line, because that would put together north and south pole and you're not working with a 4D map, are you? ;-)</p> <p>Case 1, a pole is visible: If it's the north pole, figure out which of the corners has the smallest latitude. Any latitude smaller than that is likely off-screen. If it's the south pole just reverse the logic, i.e. use the largest latitude and exclude any items with a greater latitude. I know, having the pole in one corner and the equator in another means you still include an entire hemisphere. But at least you can cheaply exclude the other half.</p> <p>Case 2, no pole, not crossing the +/-180 longitude line: Find the min/max longitude and latitude values and use those for a simple box check. Anything outside the box is off-screen.</p> <p>Case 3, no pole, but crossing the +/-180 longitude line: Same as above for latitude. For longitude, find the longitudes furthest away from +180 and -180 respectively. Exclude any items with a latitude outside the min/max or between the two furthest longitudes you found.</p> <p>The cases 2 and 3 should be able to rule out enough candidates to make a brute-force check for the others feasible. Case 1 may require further post-processing, but I'm afraid that part is a bit too complicated for me if you want something sophisticated. I suppose you could somehow find an off-screen point closest to the pole if the pole is further away from the center of the screen. Then somehow construct a triangle-like shape with one corner at that point and make it as large as possible without touching the screen rectangle.</p>

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