Distance formula from Long/Lat Coord

D

DellaCroce

Does anyone here have the formula for calculating distance give two pairs of
Longitude/Latitude coordinates? Please share this with me if you would.
 
T

Tom Dacon

Convert the latitudes and longitudes to radians, observing that latitude is
positive in the northern hemisphere, and negative in the southern
hemisphere, and by convention among astronomers east longitude is positive
and west longitude is negative (why? No one knows).

Let's call one point the 'start point' and the other one the 'end point.

Let L be the start point latitude in radians, and D be the end point
latitude in radians.

Let LHA be the difference between the two longitudes, in radians.

Then the sine of the distance angle between the two points, measured from
the center of the earth, is:

sin(distance angle) = sin(L) * sin(D) + cos(L) * cos(D) * cos(LHA)

and the angle in radians of the distance angle is:

da = asin(distance angle).

Convert this angle to degrees.

On a theoretically spherical earth, an angle of one degree subtends 60
nautical miles. So multiply the distance angle in degrees by sixty, and you
have what's called the "Great Circle Distance" between the points in
nautical miles of 6000 feet. To convert to land miles, multiply by
6000/5280.

Regards,
Tom Dacon
Dacon Software Consulting
 
D

DellaCroce

WOW!! That is exactly what I needed! Thanks, Tom.

Tom Dacon said:
Convert the latitudes and longitudes to radians, observing that latitude is
positive in the northern hemisphere, and negative in the southern
hemisphere, and by convention among astronomers east longitude is positive
and west longitude is negative (why? No one knows).

Let's call one point the 'start point' and the other one the 'end point.

Let L be the start point latitude in radians, and D be the end point
latitude in radians.

Let LHA be the difference between the two longitudes, in radians.

Then the sine of the distance angle between the two points, measured from
the center of the earth, is:

sin(distance angle) = sin(L) * sin(D) + cos(L) * cos(D) * cos(LHA)

and the angle in radians of the distance angle is:

da = asin(distance angle).

Convert this angle to degrees.

On a theoretically spherical earth, an angle of one degree subtends 60
nautical miles. So multiply the distance angle in degrees by sixty, and you
have what's called the "Great Circle Distance" between the points in
nautical miles of 6000 feet. To convert to land miles, multiply by
6000/5280.

Regards,
Tom Dacon
Dacon Software Consulting


DellaCroce said:
Does anyone here have the formula for calculating distance give two
pairs
 
U

user

Dim AdjLatDist, dif, xdist As Double

DegLatDist = 111.13295-0.55982*Cos(2*lat1)+0.00012*Cos(5*lat1)

dif = Abs(lon1 - lon2)

xdist = Acos(Sin(lat1)*Sin(lat2)+Cos(lat1)*Cos(lat2)*Cos(dif))

return xdist * (180/pi) * DegLatDist

' Result in KM - for mile multiply by .6214

Denis
 
O

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DellaCroce said:
WOW!! That is exactly what I needed! Thanks, Tom.
 

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