Mercator Meters

[+user13371]

Lowrance GPS units store coordinates internally in Mercator Meters - not to be confused with UTM (which is different and much better documented).

 

Though I've found a couple of sources online documenting how to convert between Mercator Meters and degrees decimal, I can't find anything that explains where this coordinate method comes from, why Lowrance uses it, what its distnct advantages might be, etc...

 

Has anyone else ever studied this?

Edited September 11, 2004 by lee_rimar

[+tirediron]

Sounds like some kind of oddball offshore currency! Nope, never heard of it, but if you get more info, pls post it. Sounds interesting!

[gm100guy]

Try for your answer here

 

I did this search and the third link down explained it to me pretty easy.

 

I love google.

 

Edited September 12, 2004 by gm100guy

[+user13371]

Try for your answer here

 

I did this search and the third link down explained it to me pretty easy.

 

I love google.

Right, I know how to use Google too; did my own searches a couple weeks ago. But you're either reading something differently than I am, or you didn't understand my original question. In particular, the "third link down" when I ran your search was this one:

 

http://www.nysgis.state.ny.us/inventories/cscic.htm

 

...which doesn't mention Mercator Meters as used by Lowrance at all. The SECOND link looked more promising,

 

http://home.cfl.rr.com/genecash/eagle.html

 

...since it actually DOES talk about Lowrance, but only discusses conversions and doesn't address my original query.

 

Could you point to what you thought explained it "pretty easy"?

 

---

 

Things I already knew, before posting my question in here:

 

- Lowrance GPSRs store coordinates internally in Mercator Meters

- Mercator Meters are not the same as Universal Transvere Mercator coordinates

- How to convert from Mercator Meters to decimal degrees (and back again)

 

What I don't understand is if there is some distinct advantage to this coordinate system. Does it offer some shortcut trick for calculating distances between waypoints? Is it the most efficient way to store coords in computer memory (4 bytes for lat, 4 for lon)? Or is it just something engineers at Lowrance made up and they like it because it's their own creation?

 

Is the answer lurking in Google somewhere, or in the collective knowledge of this forum?