How to find distance between two points using latitude and longitude

Question

I have a ROUTES table which has columns SOURCE_AIRPORT and DESTINATION_AIRPORT and describes a particular route that an airplane would take to get from one to the other.

Answer 1

This would have probably been a better question for the Mathematics Stack Exchange, but I’ll provide some insight here. If you are relatively farmiliar with trigonometry, I’m sure you could understand the implementation given this resource: https://en.m.wikipedia.org/wiki/Haversine_formula. You are looking to compute the distance between two point on the surface of a sphere in terms of their distance across its surface (not a straight line, you can’t travel through the Earth).

The page displays this formula: https://wikimedia.org/api/rest_v1/media/math/render/svg/a65dbbde43ff45bacd2505fcf32b44fc7dcd8cc0

Where
• φ1, φ2 are the latitude of point 1 and latitude of point 2 (in radians),
• λ1, λ2 are the longitude of point 1 and longitude of point 2 (in radians).

If you data is in degrees, you can simply convert to radians by multiplying by pi/180

Answer 2

I think you're about 90% there in terms of the solution method. I'll add in some additional detail regarding a potential SQL query to get your answer. So there's 2 steps you need to do to calculate the distances - step 1 is to create a table containing joining the ROUTES table to the AIRPORTS table to get the latitude/longitude for both the SOURCE_AIRPORT and DESTINATION_AIRPORT on the route. This might look something like this:

SELECT t1.*, CONVERT(FLOAT, t2.LATITUDE) AS SOURCE_LAT, CONVERT(FLOAT, t2.LONGITUDE) AS SOURCE_LONG, CONVERT(FLOAT, t3.LATITUDE) AS DEST_LAT, CONVERT(FLOAT, t3.LONGITUDE) AS DEST_LONG, 0.00 AS DISTANCE_CALC
INTO ROUTE_CALCULATIONS 
FROM ROUTES t1 LEFT OUTER JOIN AIRPORTS t2 ON t1.SOURCE_AIRPORT_ID = t2.IATA 
               LEFT OUTER JOIN AIRPORTS t3 ON t1.DESTINATION_AIRPORT_ID = t3.IATA;

The resulting output should create a new table titled ROUTE_CALCULATIONS made up of all the ROUTES columns, the longitude/latitude for both the SOURCE and DESTINATION airports, and a placeholder DISTANCE_CALC column with a value of 0.

Step 2 is calculating the distance. This should be a relatively straightforward calculation and update.

UPDATE ROUTE_CALCULATIONS 
SET DISTANCE_CALC = 2 * 3961 * asin(sqrt((sin(radians((DEST_LAT- SOURCE_LAT) / 2))) ^ 2 + cos(radians(SOURCE_LAT)) * cos(radians(DEST_LAT)) * (sin(radians((DEST_LONG- SOURCE_LONG) / 2))) ^ 2))

And that should give the calculated distance in the DISTANCE_CALC table for all routes seen in the data. From there you should be able to do whatever distance-related route analysis you want.

Answer 3

There is a formula called great circle distance to calculate distance between two points. You probably can load is as a library for your operating system. Forget the haversine, our planet is not a perfect sphere. If you use this value often, save it in your routes table.