Radio updates lat & long.

[RoaldLarsen]

Originally Posted by Pisces

In any event each degree is 120km in length, either way.

This cannot be correct, or the Earth would be a cylinder with a North and South circle instead of poles. The distance between degrees of longitude approaches 0 as you approach a pole.

[A Very Super Market]

Obviously, but the game map considers it to be a cylinder.

[RoaldLarsen]

Originally Posted by A Very Super Market

Obviously, but the game map considers it to be a cylinder.

Yes, the coordinate system (metres from 0°N,0°E) is effectively cylindrical, but the Kriegsmarine grid squares are not all the same width on the game map, not even at the same latitude, so I doubt one should assume a rigid 120km distance between degreees of longitude everywhere on the game map.

[Pisces]

Originally Posted by RoaldLarsen

Yes, the coordinate system (metres from 0°N,0°E) is effectively cylindrical, but the Kriegsmarine grid squares are not all the same width on the game map, not even at the same latitude, so I doubt one should assume a rigid 120km distance between degreees of longitude everywhere on the game map.

Who says the KM grids should be all of the exact same size? Or aligned to the same degrees? It is more appropriate for the KM to align those grids to actual shorelines. There's no point in having halve of a grid covered with real-estate where you can't swim.

In any event if you measure the distances of several cities or shoreline-features to the Greenwich meridian and equator you'll see that 120km number appear quite accurately once you divide the lengths by the actual lattitude/longitudes in Google Earth for example..

[Sailor Steve]

Originally Posted by Pisces

Who says the KM grids should be all of the exact same size? Or aligned to the same degrees? It is more appropriate for the KM to align those grids to actual shorelines. There's no point in having halve of a grid covered with real-estate where you can't swim.

Actually they did exactly that. Check out any of the maps here:
http://www.geocities.com/germangrid/eindex.html

[Pisces]

Yes, more or less. On the same parallel (equal lattitude) they have the same with. But higher up north/south they have different width. The big 2-letter grids fall out of step with each other. Which makes sense as a degree of longitude becomes smaller as you approach the poles. And so you make up for the area they contain.

I.e. that AG grid (see link below) is a weird one. My point was they fudged the borders (clipped some of the inner grids) a bit to make them fit better to the shores.

http://www.geocities.com/germangrid/enorthenteat.html

[RoaldLarsen]

Originally Posted by Pisces

Who says the KM grids should be all of the exact same size? Or aligned to the same degrees? It is more appropriate for the KM to align those grids to actual shorelines. There's no point in having halve of a grid covered with real-estate where you can't swim.

In any event if you measure the distances of several cities or shoreline-features to the Greenwich meridian and equator you'll see that 120km number appear quite accurately once you divide the lengths by the actual lattitude/longitudes in Google Earth for example..

I think we are talking at cross purposes here.

You are absolutely correct that the game models 1 degree of latitude or longitude anywhere on the map to be 120km. So to convert a Lat/Long position in a radio message to a position on the game map, just multiply by 120 and measure from 0/0 which is somewhere down in quadrant FG.

When I said "This cannot be correct..." I did not mean you were incorrectly describing how the game map works. I meant that the game map incorrectly models the real world. Therefore one cannot get real world positions or distances by multiplying latitude and longitude by 120. One cannot assume a real world 120km / degree.

For instance, if you measure the distance on the game map from Narvik to Reykjavik, you get a distance of about 4745km. In reality, those two locations are only about 1780km apart.

The Kriegsmarine quadrants were, AFAIK, designed to be about the same actual size, so their width in degrees was bigger at higher latitudes. This means that the real world distance across a KM grid square was approximately the same anywhere on the KM map, but the in-game distance across a KM grid square on the game map varies greatly with latitude.

Narvik and Reykjavik are in AG1152 and AE4811 respectively, which is a horizontal displacement of 157 squares and a vertical displacement of 42 squares. If we take corresponding positions near the equator, for instance FG1152 and FE4811, and measure those on the game map, we get 1950km. This is much closer to reality, but still too big. This is in part because the 120km/degree approximation that the game uses is too big, even at the equator. A more accurate approximation for a degree of longitude at the equator or a degree of latitude anywhere is 111km.

[Pisces]

Ok, in my post I should have made more clear that I was only talking about in-game relation between km and degrees. Sure, a degree on the real earth isn't 120km in length. 111km is closer but not even that since the real earth is a bit of a flatened sphere. BTW real kilometers, as wel as nautical miles, actuallly originated from a division of lattitude, not longitude. Anyway I am playing the game, so I focus on the size of the world in there. Too bad the sub endurance doesn't reflect real endurance anymore.

Originally Posted by RoaldLarsen

When I said "This cannot be correct..." I did not mean you were incorrectly describing how the game map works. I meant that the game map incorrectly models the real world. Therefore one cannot get real world positions or distances by multiplying latitude and longitude by 120. One cannot assume a real world 120km / degree.

For instance, if you measure the distance on the game map from Narvik to Reykjavik, you get a distance of about 4745km. In reality, those two locations are only about 1780km apart.

Distances 'as the crow flies' (point to point), agreed, those would be distorted since the map is stretched at the poles. But locating real Lat./Long. positions by converting to kilometers by multiplying by 120 DO represent the actual locations. Just think of those Sh3-'kilometers' as being halve arcminutes.