Distance between points by EPSG coordinates

Question

I have a points with coordinates EPSG Projection 3059 - LKS92 / Latvia TM. I need to compute the distance in meters between two points.

It is easy to compute euclidean distance between two points, but I am not sure if the resulting distance is expressed in meters?

PROJCS["LKS92 / Latvia TM",
 UNIT["metre",1,
 PARAMETER["scale_factor",0.9996],

The unit is 1 meter, but should the scale factor taken into account? Maybe 1 unit in this system is not 1m but 0.9996 meters?

Answer 1

No, the scale factor in a map projection is integrated in the projection calculations. The purpose of the factor is to minimise overall distortion as the easting from the central meridian (24°E) increases. 0.9996 is a common factor when transverse mercator (TM) is involved.

Once projected, the resultant coordinate is in metres (in this case), no further scaling is needed, and you can use a simple Pythagorean hypotenuse calculation to determine a distance.