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Old 06-05-2007, 09:59 AM   #1
Mav87th
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Default Real Navigation with SH4

Tests of GMT times versus "Base Time" as the clock is called in SH4 shows, that sun sets and raises look to be just as usable as in SH3 even down to minutes.

The only problem that remains are WHAT TIME ZONE ARE BASE TIME ??? and how does it change over time. I know that it does not change when you save the game (im keeping a logbook and times match whenever i go back into a new saved game)


Below an example:

Game date - 22 november 1942 - located on E 144 deg 50 / N 26 deg 50

I started the stopwatch as the game clock changed minutes, so to have seconds available.

in 3D the sun SET was

Lower Limb - 19:15:00 @ 247 deg True

Center sun - 19:29:10 @ 248 deg True

Upper Limb - 19:40:15 @ 250 deg True


From Almanac data (Starcalc) the real GMT sun SET should be 17:05:00 @ 247 deg True

Difference (to center sun) is + 2 hours 14 minutes or - 16 hours and 36 minutes


3d measurement of Polaris were 310 deg True at 31 deg up from horizon at game Base time 19:57:00

The submarine were parked the same spot the whole time.


Now can anyone tell me what timezone the BaseTime is???

or if this corrosponds with my position lat/lng ?
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Old 06-05-2007, 05:54 PM   #2
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bump for reads.... this is (potentially) a realism breakthrough waiting to happen
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Old 06-05-2007, 06:22 PM   #3
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I believe I have a copy of starry night pro, I will give it a shot if you want to make some tests.
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Old 06-05-2007, 09:19 PM   #4
Mav87th
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todays testing showed, that the starmap is correct as far as to the dates (22. november 1942).

I have now rescaled the SH3 mod's Sextant image and printed it on a transparent, thus enabled a measurement of Polaris for Latitude. And this seems to work fine.
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Old 06-05-2007, 10:34 PM   #5
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I believe the time is based on Pacific Standard Time however, the dateline issue isn't implemented therefore the clock keeps ticking away at wherever you start off.
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Old 06-06-2007, 07:11 PM   #6
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Quote:
Originally Posted by Mav87th

Upper Limb - 19:40:15 @ 250 deg True


From Almanac data (Starcalc) the real GMT sun SET should be 17:05:00 @ 247 deg True
I put all data in starry night:

sunset 17:04 @247° (gmt+09:36)
if the game renders the sunset at 19:40, that would be gmt+12:12!

timezone is fubar in sh4
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Old 06-06-2007, 11:38 PM   #7
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Quote:
Originally Posted by kv29
if the game renders the sunset at 19:40, that would be gmt+12:12!

timezone is fubar in sh4
Not necisarily - but the gameclock is just not simple "local time" - i think its based on something els. The trick is to figure out WHAT Base Time is exactly and then just make the calculations from there. It does not matter if you have to say Local time +12 or Base Time +10 - as long as you know that its +10 or whatever it is...
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Old 06-07-2007, 02:07 AM   #8
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I wouldv'e thought that base time was from the base you departed from.

Showing local time would be my preference same as in SH3 but again crossing the dateline is the issue.
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Old 06-07-2007, 08:28 AM   #9
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@kv29 you're right!


after some testings I found:

- base time is real local time of the exact position the sub starts
- that means: there are no time zones in SH4 - there is a continuous displacement of time


If You start at W001°00' your "local time" = basetime ist 4 Minutes behind GMT.

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Old 06-07-2007, 08:31 AM   #10
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So if the clock is ok, time measure should remain accurate for the rest of the mission, or the clock is bad too?
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Old 06-07-2007, 08:36 AM   #11
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Quote:
So if the clock is ok, time measure should remain accurate for the rest of the mission?
Yes!

And we need the time difference (local time - GMT) for every start - location.
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Old 06-07-2007, 08:44 AM   #12
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is there any way to mod the "timezone"?
we need an onscreen sextant mod!
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Old 06-07-2007, 08:50 AM   #13
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there is a sextant for SH3, but it doesn't work in SH4 - i do my best



SH3 Sextant: http://www.subsim.com/radioroom/show...eal+navigation


Edit:
@Mav87th
Sorry didn't read your postings completly
Quote:
or if this corrosponds with my position lat/lng ?
YES!


Does the sh3 - sextant work for you?
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Last edited by Minimax; 06-07-2007 at 09:10 AM.
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Old 06-07-2007, 09:51 AM   #14
Mav87th
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Quote:
Originally Posted by Minimax
And we need the time difference (local time - GMT) for every start - location.
So when one starts in PEARL one needs use PEARL time - TimeDif = GMT at all times while sailing...

Question is, will this be valid as well if one starts outside the harbor, or will it default to your homebase time there as well.....
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Old 06-07-2007, 10:19 AM   #15
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Here's an interesting pic of UL sun just dipping beneath the waves. My location: 28-15N 177-32W. What you see is the orange after-glow. The defined circumference of the sun has just disappeared.

Note the time: 18:45. (The interior "RED" light popped on at the same time!)

Well guess what...it seems that base time in SH4 is at the International Date Line, just west of Midway Is. 180°. All other times must then be computed by the player as they make their way across the Pacific.

18:45 btw coincides with my TI-86(Starpath) ephemeris calc/nav pgm., for SS at my posit also. Don't know if you can see my relative bearing of the sun as he dips, but it's 144° that also coincides with 258° true, the actual azimuth of the setting sun on the RL nav pgm.

Scope: #1 aka Observation scope.
Mod: RFB 1.28

Note: reposted from SH3 Mod forum.
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