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<body class='hmmessage'><div dir='ltr'>Hi all,<br><br>I am still trying to find a better solution for the problem<br>posted by Roger Calvert:<br><a href="http://gis.19327.n5.nabble.com/Incorrect-compilation-of-grid-lines-tp5809502.html">http://gis.19327.n5.nabble.com/Incorrect-compilation-of-grid-lines-tp5809502.html</a><br><br>We are using some approximations to speed up calculations,<br>most of them work fine as long as distances are rather short.<br><br>On the other hand, mkgmap doesn't check if distances are short,<br>so in some cases we have rather large errors.<br><br>I found two sources for formulas:<br><a href="http://www.movable-type.co.uk/scripts/latlong.htmlhttp://www.movable-type.co.uk/scripts/latlong.html">http://www.movable-type.co.uk/scripts/latlong.html</a><br>and <br><a href="http://williams.best.vwh.net/avform.htm">http://williams.best.vwh.net/avform.htm</a><br><br>The latter gives an example to verify the code. I've coded<br>some lines in Java and got similar results as in the "worked example".<br>I've then tried to verify the example in JOSM,<br>esp. the cross-track-error.<br>Unfortunately, when I try to draw a (nearly) perpendicular<br>line from point A to line LAX-JFK, JOSM says the line is ~27.7 km <br>long, while the example calculations are near 13.8 km or<br>about 50% of the JOSM value.<br><br>What am I getting wrong?<br><br>Gerd<br><br> </div></body>
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