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Re: Re: How do I compute the longitude and latitude of a point at a certain distance?

by Bilbo (Pilgrim)
on Apr 22, 2003 at 08:32 UTC ( [id://252218]=note: print w/replies, xml ) Need Help??


in reply to Re: How do I compute the longitude and latitude of a point at a certain distance?
in thread How do I compute the longitude and latitude of a point at a certain distance?

I think that this is almost right, but not quite. c/360 gives the distance north-south per degree, whereas what we actually want is degrees per unit distance NS, ie 360/c. Similarly for the distance EW. We want the final result to have dimensions of an angle but the equations that you give have inconsistent dimensions (angle + distance^2/angle).

The two equations should be:

  • x' = x +- ( 360 / c' ) * EW
  • y' = y +- ( 360 / c ) * NS

The mean radius of the earth is 6371 km (NASA), so c = 40030 km.

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Re: Re: Re: How do I compute the longitude and latitude of a point at a certain distance?
by zengargoyle (Deacon) on Apr 22, 2003 at 09:06 UTC

    you are so correct! i should have made a units thingy.

    

360 deg  |  EW m    360*EW deg  
---------|------- = ----------
 c' m    |    1         c'
    <
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