Lat long to utm conversion?

[stevieray]

Hi,

I'd like to practice using the CDU to add mission points in UTM since that's what JTAC normally gives you. If I put objects on the map in mission editor, is there a way to get the UTM cords or convert from lat long? My goal is to create a mission and try entering the cords for the units I place and try to find them via the CDU. I'll go back and read the manual, any help would be great. Thx!

Steve

[Hansolo]

In the options menu in DCS you can set what coordinates you want to see; UTM, lat/long or lat/long decimal

 

cheers

Hans

[WildBillKelsoe]

You can switch LL to MGRS in CDU (you'll find the RSK on CDU)

[JayPee]

http://www.earthpoint.us/Convert.aspx

[stevieray]

Thanks! One thing I still don't get is the WG84 in the CDU a line above the MGRS line. I think it's the overall grid square reference but how do I know when to change it / what to change it to if the waypoint I'm setting happens to be outside? I know this happens if the distance to the wp is waay off. I'm confused when I look at the map, I don't see WG84 anywhere. Sorry if this is a silly question..

[Yurgon]

Thanks! One thing I still don't get is the WG84 in the CDU a line above the MGRS line. I think it's the overall grid square reference but how do I know when to change it / what to change it to if the waypoint I'm setting happens to be outside? I know this happens if the distance to the wp is waay off. I'm confused when I look at the map, I don't see WG84 anywhere. Sorry if this is a silly question..

 

A new World Geodetic System: WGS 84; AFAIK this information is static, and I'm sure you don't need to change it in day-to-day use.

 

The coordinates being off have to do with the UTM grid zone. Check this visualization.

 

Thus, if you're starting in 37T and your target is located to your east or the other way around with 38T, this is what you'll have to change: 37T -> 38T or the other way around. Just leave WG84 at its current value (TBH I don't know if it's possible to change the value even if you wanted to ;)).

 

Finally, it would be cool if JTACs always included the UTM grid zone, unfortunately that's not the case. Some well designed missions do that, though.

 

TL;DR: As a rule of thumb, if your coordinates are hundreds of miles away, swap 37T for 38T or the other way around. :thumbup:

[stevieray]

Makes sense, thanks for the help!

[StrongHarm]

Attached is a paper that should give you a complete understanding of UTM and MGRS if you're interested.

MGRS.pdf

[Yurgon]

Attached is a paper that should give you a complete understanding of UTM and MGRS if you're interested.

 

Very interesting, but also dry reading. In any case thanks for sharing! :thumbup:

 

I have a question regarding the document. AFAICT from reading it, the easting letter for a 100,000 meter square ranges from A to Z while the northing letter only ranges from A to V (both omitting I and O because these could be easily confused with 1 and 0); see the graphic "Basic Plan of the 100,000 meter Square Identifications of the Military Grid Reference System" on page 3. Why is that?

 

On a side note, the "degree" symbol isn't displayed inside text paragraphs for me when reading the document; that might be a peculiarity of my PDF reader (Foxit reader). If not, that would be rather annoying because some sentences don't make a whole lot of sense with this symbol missing.

[StrongHarm]

Yurgon, my best guess is that there's two reasons: One, the earth isn't actually round, it's ellipsoidal. Two, check out Universal Polar Stereographic(UPS) which changes the lettering at the poles.

 

Here's an excerpt:

The lettering scheme for 100,000 m squares is slightly different in the polar regions. The row letters go from A to Z, omitting I and O. The column letters use a more restricted alphabet, going from A to Z but omitting I, O, D, E, M, N, V, W; the columns are arranged so that the rightmost column in grid zone A and Y has column letter Z, and the next column in grid zone B or Z starts over with column letter A. The restricted column alphabet for UPS ensures that no UPS square will be adjacent to a UTM square with the same identification.

 

Of course it's dry reading.. did you expect they'd throw in some geospatial humor? :)

Edited April 10, 2015 by StrongHarm

[Yurgon]

Yurgon, my best guess is that there's two reasons: One, the earth isn't actually round, it's ellipsoidal.

 

Interesting thought, but it isn't (yet) obvious to me why that would limit the 100,000 meter square Northing letter by 4 letters (W, X, Y, Z).

 

Two, check out Universal Polar Stereographic(UPS) which changes the lettering at the poles.

 

Here's an excerpt:

The lettering scheme for 100,000 m squares is slightly different in the polar regions. The row letters go from A to Z, omitting I and O. The column letters use a more restricted alphabet, going from A to Z but omitting I, O, D, E, M, N, V, W; the columns are arranged so that the rightmost column in grid zone A and Y has column letter Z, and the next column in grid zone B or Z starts over with column letter A. The restricted column alphabet for UPS ensures that no UPS square will be adjacent to a UTM square with the same identification.

 

For several reasons, I don't think this explains it.

• I took the example from grid zone 1Q, which is close to the equator and thus about as far from the poles as possible.
  
• The excerpt states that "row letters go from A to Z". If we're looking at MGRS like a table, the Northing would be "rows", stating the opposite of what I observed in the document.
  
• For the column letters (Easting) it says they're "going from A to Z but omitting I, O, D, E, M, N, V, W", again not conforming to the observation that the Northing letters range from A to V (omitting I and O).
  

 

I don't think this UPS thing has anything to do with it.

 

**************************************

 

But I took another close look at that graphic and things are becoming more confusing rather than less.

 

The graphic depicts grid zones 1N (International Date Line at 180° West longitude, 0° latitude) through 3Q.

The first 100,000 meter square Northing/Easting letters are AA, which is to be expected. But going east, 1N HA is next to 2N JF (where I'd have expected JA instead of JF). Then 2N RF is neighbors with 3N SA (where I'd have expected SL if the Northing letter moved by another 5 letters in the alphabet).

 

This pattern is actually repeated in the DCS mission editor, clearly visible when zooming all the way out.

 

So by now I have two observations I don't yet understand:

• 100,000 meter square Northing letters seem to be limited from A to V (as always, omitting I and O) whereas the Easting letters range from A to Z
  
• Adjacent grid zones appear to toggle the Northing 5 letters up/down
  

 

Of course it's dry reading.. did you expect they'd throw in some geospatial humor? :)

 

Would have been nice. :)

 

My impression was that it doesn't go from A to B to C in a clear line; it's more like going from A to C and then casually mentioning B on a side-note. I didn't expect prose, but I think didactics-wise there's room for improvement.

 

Anyhow, I did learn a great deal about MGRS and I'm grateful for the document. It's just that it opens up a couple of new questions. :smartass:

Edited April 10, 2015 by Yurgon
Fixed square meter vs. meter square