2009/9/28 Brian Modra <[email protected]>: > 2009/9/28 Malm Paul <[email protected]>: >> Hi list, >> I would like to select data over the north pole inside a polygon of lat/lon >> coordinates >> For selection I create a polygon from theese coordinates >> >> 1) 80, -170 >> 2) 80, 170 >> 3) 75, 10 >> 4) 75, -10 >> >> But is seems that the objects found are from around the pole instead of over >> the pole, it does not find any objects over 80° >> Is ther a way to get around this? > > This is a wild guess, having not looked at the PostGIS code, and not > knowing how your data is stored, but I wonder if you need to put in > more coords, because depending on the prjection, the lines joining > those 4 points could be kind of weird. > > e.g. > 80 0, 80 20, 80 40, 80 50, 80 60... 80 180, 80 -160, 80 -140 ... 80 0
Another question for the experts: what is the inside of the polygon in the above example? Is it above 80, or below 80, or is the polygon joined up as a straight line at 80 degrees? I.e. with zero area? maybe a better polygon would be: 80 -170, 80 -150, 80 -130 ... 80 150, 80 170, 75 170, 75 150, 75 130 ... 75 -150, 75 -170, 80 -170 > >> Kind regards, >> Paul >> _______________________________________________ >> postgis-users mailing list >> [email protected] >> http://postgis.refractions.net/mailman/listinfo/postgis-users >> > > > > -- > Brian Modra Land line: +27 23 5411 462 > Mobile: +27 79 69 77 082 > 5 Jan Louw Str, Prince Albert, 6930 > Postal: P.O. Box 2, Prince Albert 6930 > South Africa > http://www.zwartberg.com/ > -- Brian Modra Land line: +27 23 5411 462 Mobile: +27 79 69 77 082 5 Jan Louw Str, Prince Albert, 6930 Postal: P.O. Box 2, Prince Albert 6930 South Africa http://www.zwartberg.com/ _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
