From: Clyde England <cwe@ii...> - 2004-03-07 01:56:50
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
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
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
Any ideas where I might be coming unstuck here?
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