Transformation between Latitute- Longitude to X-Y in meters.

This is infact `transformation between ECEF and Flat-Earth Coordinates` and it can be a messy work to transform a latitude (degree) to meter in order to conduct analysis in body-fixed frame. Because I have encountered lack of explanation and solution about this issue when writing codes for autonomous surface ships, I have decide to post this article.

Here, I provide an explanation that show how to find distance of a position (lat,lon) from origin (0,0) in meters.

We need to find x an y (z is for altitude, we ignore for now).

The required paramters are;

`l` stand for longitude and `u` stand for latitude. However, it is important to note that the result (x,y) refers (east,north) which means x in the distance in west-east direction and y is the distance in north-south direction. Below you can find a Python Code that makes the calculation;

I have validated this transformation with pyproj package transformer module.

Sources: Fossen, Thor I. Handbook of marine craft hydrodynamics and motion control. John Wiley & Sons, 2011.