Hi Y'all, Martjin has added self-intersection checks to the coastline error checker. :-) That's what those purple dots are. Of course since we've never looked for them before there are now about 6000 new errors.
If anyone ever finds a false positive self-intersection, please email me, I will investigate. The intersection math is floating point so it could fail for very near "grazings" but given the size of the earth and the limits of double-precision floating point, a near-miss that triggers the coastline is probably creating an insanely small "pinch" of water, smaller than would be useful. (The coastline generation process also reduces data density, which has the potential to collapse such a small pinch.) Currently self intersections do not create total map rendering failures. The major map renderers appear to use a "toggle" policy toward polygons, thus a figure 8 closed polygon is filled in its two enclosed areas. Self-intersections render the notion of "one side is wet, the other is dry" impossible of course. There are self-intersection tests in some of the other quality-assurance tools, but I think a lot of them are available only in Europe. (Perhaps that is why the US coast has so much more purple than Europe?) cheers Ben -- Scenery Home Page: http://scenery.x-plane.com/ Scenery blog: http://xplanescenery.blogspot.com/ Plugin SDK: http://www.xsquawkbox.net/xpsdk/ X-Plane Wiki: http://wiki.x-plane.com/ Scenery mailing list: [email protected] Developer mailing list: [email protected] _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev
