Thread: [Gpsbabel-misc] Polygon Filter
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robertl
From: Clyde E. <cw...@ii...> - 2004-03-07 01:56:50
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GPSBabel Windows, V 1.22 02222004 I am having trouble getting a polygon filter to work as I would expect. Although I suspect the problem is only 3 foot from the keyboard here is my issue: I selected 4 caches as the basis for my polygon (a very skewed looking rectangle). When I run the filter against a bunch of caches, only one of the 4 caches I used to set up the polygon get into the result set. I would expect all or none. I have checked that the coordinates for the 4 points and the incoming gpx file that contain these 4 points match exactly. Perhaps some rounding thing when doing the calculation? My other issue is when I look at this polygon on the map I can see 3 caches that I believe should be inside the polygon, yet only one comes up in the result set. Although not specifically stated in the documentation I also suspect the order of the points creating the polygon is significant. I say this because I tried all sorts of permutations changing the order of the coordinates and did manage to get a different number of points returned in the result set at times. However, at no time did I manage to get a result set that contained ALL the caches I believe should be in the result set. In all cases I made sure the first and last point were the same. That is, there were always a total of 5 points in my polygon coordinate file. I can provide input file, polygon coordinates, and command syntax, if needed. However, I thought I would hold back on this because it may just be something obvious or my limited understanding of how the polygon filter works. Any ideas where I might be coming unstuck here? Thanks Clyde |