Land navigation #2

Today was a rest day from any physical activity thus taking some time of doing theory. I spent some time watching youtube and reading articles on the internet. Unfortunately I am not at home where I have my book Ultimate Navigation Manual which I started to read a few weeks back, but so far I really like the book.


I mainly focused on maps and coordinate systems tonight and in this post I will try to summarise shortly what major information I learned / refreshed from earlier.

  1. Latitude and longitude: the equator is the 0° angle horizontal parallel (reference parallel to measure latitude) and the prime meridian is the 0° vertical line passing through Greenwitch, England (reference parallel to measure longitude). For example, the north pole is 90° N latitude and Stockholm about 18° E longitude.
  2. Geodetic datum: a (reference) system and a set of reference points in order to associate points on earth. Every coordinate system depend on which model of earth is used, e.g. the geodetic datum WGS84 is the reference system used in GPS. In Sweden we use SWEREF99.
  3. Grid system: converting the longitude and latitude on a sphere shape of earth down to a 2-dimensional surface is done by map projection, using a grid system. UTM and MGRS are the ones I will learn more about (as well as the old Swedish system called RT90). UTM is using the WGS84 datum.

Next time I will do some drills in taking out points in UTM and MGRS on a map.


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