View Full Version : Great Circle Nav Routes?

06-29-2005, 11:25 AM
Just out of curiosity...

Anyone checked to see if great circle routes work in the game? ...or is the map already sufficiently skewed to account for that with straight line routes?

Seems to me I did notice some patrol zones larger than others. I think they got the line of site correct (ie. ships appear low on horizon due to curvature of Earth, etc).

06-29-2005, 09:24 PM
Measure across square FC right at the equator. Then measure acreoss square DS right at the top. If both lengths are the same then I would say no to great circle routs.

06-30-2005, 02:10 AM
No, they did not get the line of sight correct - they are just faking it. Try looking through the periscope at some ships which are just showing their masts. If you raise the periscope you dont get to see more of the ships as you should. Silent Hunter II did this correctly, with the periscope raised you could see further over the horizon.
As to the great circle distances...I havent tried, but I would be REALLY surprised if the gameworld in SH3 would be a sphere. It´s easy to test, though. Set a course straight to east or west (the further north you are, the better this works) Travel for a couple hundred miles, and see if the heading indicated changes. If it does, you are traveling on a orthodrome, the great circle. If it doesnt, you are on a flat world. If you are traveling on a constant heading in the real world its called a loxodrome, which is actually a curved line.

06-30-2005, 12:36 PM
Well... I kinda just figured raising the parascope wasn't REALLY enough of a change in POV to make that big of a difference.

Maybe it is faked, but at least they've got something... and I think the 5 mile (8000M) visible range is close to correct for a LOS.

I'll play with it a bit, but yeah, I would indeed be surprised if great circle holds true. Imagine the typical gameboy response they'd have to put up with, "Hey, there's a bug here, a longer route is a shorter travel time!"

06-30-2005, 12:44 PM
Originally posted by lecek:
Measure across square FC right at the equator. Then measure acreoss square DS right at the top. If both lengths are the same then I would say no to great circle routs.

Well, not necessarily. Depends if the flat map is a Mercator projection. (I shoulda checked...)

I'll look when I get home, it should be obvious on the world map when looking at Greenland vs. South America (in reality S. America is 7x the size of Greenland). On a Mercator, Greenland looks a tad bigger than S. America.

06-30-2005, 01:15 PM
You don't need to check the size of greenland to see what kind of projection it is. The map shows the lat long grid in perfect squares.

On the map FC and DS are directly north and south of eachother and are the same size. However DS is much farther north and SHOULD be smaller.

My point is independent of the map, that is the glob may be correct but the map is still Mercator so that great circle routes work.

One way to check is to see if the same length of east to west line reports the same length on the map regardless of how far north it is. If the line reports the same length then you know it is modeled wrong. (BTW it does report the same length.)

06-30-2005, 01:26 PM
Bare with me, I'm no cartographer.

The map is not all perfect squares.

OOOPS! edit:
Yes, I'm an idiot... You are correct it is perfect squares lat & longitude. I was looking at those silly quadrants.

Looks like they used the mercator and skewed the land and sea masses considerably.

Just trying to get a feel for what kind of size is the ocean I'm playin in.

Was also curious if I could sail East to get to West. (Is there even a sub to test that with?)

06-30-2005, 01:37 PM
Apparently we play in a mercator world with a larger than reality ocean. Or am I just a complete map moron?

Lemme see... that means direct north-south routes are accurate but east-west is only correct on the equator. Is that right? Or is it just whacked either way?

06-30-2005, 03:31 PM
Could be that the map is most accurate at 45 north/south lat. Places closer to the equator are shown smaller then they really are and opposit poleward. This would give most accurate distances closer to homewaters where we opperate most. That is how I would have done it.

However I suspect that you are correct, our ocean is oversized.

If you take a sub with the most range (D2?) and set its spead to 3 or 4 kts you have the best chance of going around the world. you don't have to make it all the way. Just better then 50% one way and then the other. I know you can't measure through 180.

07-01-2005, 01:19 PM
As for raising the periscope: If you raise the periscope for 5 meters you will be able to see 5 meters more of the ship (from the mast down). So even a few meters could make the difference between being able to spot masts and or even some superstructure. But with the ridiculously short viewing range in this game it doesnt matter that much.

07-01-2005, 01:57 PM
...and you guys are sayin that they didn't model it so it works that way?

I actually felt a little silly cruising around on the surface with the parascope fully extended. Hehehe... I recall on at least a couple occasions, after accelerating time on the map for several hours to pass, I wandered up on deck and noticed the scope fully extended. In which case I started yelling at my XO who was standing right there looking a slight bit embarrassed. "Perhaps we should light off some fireworks, too? Who keeps leaving this @#%#%! scope extended? You guys have been up here for 4 hours and not one of you noticed this huge flagpole? Must I issue a command for anything to get done around here? LOWER SCOPE! ...and if I forget to mention it, use the toilet."

Aside from the physics model in this game, anyone know if any U-boat commanders would actually do something like that in real life to see farther???