http://academic.brooklyn.c

hec",)

Solved

Posted on 2006-05-25

If I have a latitude/longitude value and DISTANCE value, How can I compute the latitude/longitude which is at “DISTANCE” miles from the given latitude/longitude value?

10 Comments

http://academic.brooklyn.c

hec",)

Assuming the world is a sphere and “DISTANCE” is measured along a great circle.

“DISTANCE” =

arcsin(sqrt(

(sin(latitude1)-sin(latitu

+ ((sin(longitude1)*cos(lati

+ ((cos(longitude1)*cos(lati

)/2)*circumfrence of earth/pi

If the latitude value is 14.52 degrees, I need the latitude delta value within 50 miles of distance.

I know the result would be around ~0.01 degrees

Imagine a point on the Earth. Now draw a circle around this point with a radius of "distance". The corresponding lat/long values that you're looking for could be _anywhere_ on the circumference of that circle.

And even if you specified one of the values (either lat OR long) for the point you're trying to find, it would still be ambiguous; as a circle is a many-to-many function, and you'll end up with 2 possible solutions.

You need to have some more info.

(a little more near the equator, a little more near the poles)

But I need exact value for longitude, how can I figure out the exact difference as distance in 1 degree of longitude differs at equator and poles.

Approcimating the earth as an ellipsoid http://kai.er.usgs.gov/ftp/PROJ.4/proj.html

R' = a * (1 - e^2) / (1 - e^2 * sin^2(lat))^(3/2)

where a is the equatorial radius, b is the polar radius, and e is the eccentricity of the ellipsoid = (1 - b^2/a^2)^(1/2).

Title | # Comments | Views | Activity |
---|---|---|---|

Delphi Mdi application Child forms get behind control | 7 | 74 | |

wefewf | 2 | 28 | |

How Complex Is This Java Course ? | 9 | 52 | |

delphi parse string to params | 3 | 49 |

Join the community of 500,000 technology professionals and ask your questions.

Connect with top rated Experts

**21** Experts available now in Live!