[mkgmap-dev] [Patch] Reduce bearingTo() calculationsFrom GerdP gpetermann_muenchen at hotmail.com on Sun Mar 4 21:05:20 GMT 2012
Hi WanMil, the calculation in bearingTo() involves a lot of rounding errors because of the trig. functions. I verified that no value differed more than 0.5, which is good enough for us since we only use the integer value. See also http://www.movable-type.co.uk/scripts/latlong.html It says: "For final bearing, simply take the initial bearing from the end point to the start point and reverse it (using θ = (θ+180) % 360)." That's what I tried to implement. Gerd WanMil wrote > > Hi Gerd, > > I have checked your patch by comparing old bearing to results with new > results. I got lots of differences as you can see by trying attached > patch. > > Can you please carefully check why there is a difference and which > version is 'better'? > > WanMil > > > >> Hi, >> >> in class RoadNetwork we calculate both p1.bearingTo(p2) and the reverse >> p2.bearingTo(p1). >> I think the reverse value should be calculated from the initial value. >> >> See attached patch. >> >> Gerd >> >> http://gis.19327.n5.nabble.com/file/n5533880/bearingTo.patch >> bearingTo.patch >> >> -- >> View this message in context: >> http://gis.19327.n5.nabble.com/Patch-Reduce-bearingTo-calculations-tp5533880p5533880.html >> Sent from the Mkgmap Development mailing list archive at Nabble.com. >> _______________________________________________ >> mkgmap-dev mailing list >> mkgmap-dev at .org >> http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev > > > _______________________________________________ > mkgmap-dev mailing list > mkgmap-dev at .org > http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev > -- View this message in context: http://gis.19327.n5.nabble.com/Patch-Reduce-bearingTo-calculations-tp5533880p5535815.html Sent from the Mkgmap Development mailing list archive at Nabble.com.
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