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<DIV><FONT face=Arial size=2>I'm working with some NEXRAD radar data and reading
the binary data and drawing it on a map. I'm using Mapserver on the
backend to produce the map. What i'm basically doing is calculating 124
nautical miles (142 statute miles) from a center point (the radar) and then
drawing my radar data on top of that. I found this nifty little formula on
the net that supposedly converts nautical miles to statute miles but it doesn't
seem to really be working as expected.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>The formula is as follows:</FONT></DIV>
<DIV><FONT face=Arial size=2>(((sm * 0.0254) * 63360) / 1852) / 60 =
nm</FONT></DIV>
<DIV><FONT face=Arial size=2>where sm = statute miles and nm = nautical
miles</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>At that point I take the value that I receive above
and do the appropriate + or - calclations from the radar's location (lat/long)
and get the extent for the map which is pushed through the URL. What I've
noticed is that the latitude seems to be correct but the longitude always falls
short 20 or 30 miles from what it should be (almost cutting off a county on
either side). Has anyone else experienced this? I've checked the x
and y distances and they are both equal. I'm producing a 460 x 460 GIF
image that uses the nationalatlas.gov SHP files. I'm using the county and
states sets.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I can post my .map files and anything else that
might be helpful (including sample images).</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Thanks</FONT></DIV>
<DIV><FONT face=Arial size=2>Kelly Koehn</FONT></DIV>
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