Re: New openGIS functionality in MySQL available for testing

[Daniel Zburivsky]

Hi,
I'm testing new GIS functionality and would like to know how the DISTANCE function is currently implemented. Particularly, does it calculate distance on the Earth's surface?

As an example I used the following:

Coordinates of Ottawa are: Lat:45.424, Long:-75.695, coordinates of Los Angeles: Lat:34.051, Long:-118.254.

To calculate distance I've used a calculator found here:http://www.movable-type.co.uk/scripts/latlong.html . It uses Haversine formula. The result is 3802 km, which seems to be true.

Now let's calculate the same distance using MySQL function:


SELECT DISTANCE(GeomFromText('POINT(-75.695 45.424)'), GeomFromText('POINT(-118.254 34.051)'));
+-----------------------------------------------------------------------------------------+
| DISTANCE(GeomFromText('POINT(-75.695 45.424)'), GeomFromText('POINT(-118.254 34.051)')) |
+-----------------------------------------------------------------------------------------+
| 44.052396189084 |
+-----------------------------------------------------------------------------------------+

This gives us quite strange result. Which even doesn't correspond to the result of a simple math formula calculating geometrical distance between two points sqrt((x2-x1)^2+(y2-y1)^2), which gives the number of 194.

Thanks in advance!