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Old 11-19-18, 11:43 AM   #1
Front Runner
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Default Base Time 2018

UPDATE Base Time 2022

Base Time is as drifty as a Seaman Recruit on their first day at Great Lakes Naval Training Center!
Many of us have difficulty in making our Base Time adjustments from Zone to Zone when traveling east-west. Sometimes, the Sun or Moon Rise/Set times are so out of whack with our observations, even when making careful adjustments to our Base Time, that we just give up on it all. The following may explain why and what is happening. [EDIT] It appears that Careers starting in Pearl Harbor are using the Midway Base time. Midway is 11 hours west of GMT (UTC). Pearl Harbor Time is 10 hours west of GMT (UTC) but is physically 11 hours west of GMT (UTC). I checked Sunset and Sunrise times using the Almanac link below. I'm looking for verification. Thanks.

I've made many observations while remaining in the Brisbane Base Time Zone. My subs Base Time clock indicates what the local time is in the Brisbane Time Zone, 10 hours east of Zulu time. For my observations I did not transit east-west, outside the Brisbane Zone. I transited only from Brisbane north to the Bismarck Sea. I used the US Navy Sun or Moon Rise/Set Table for One Year as my Almanac times. (1944)

NOTE !!! Sept. 23, 2022 - GOOD NEWS! The below link is now back in operation. US Naval Astronomical Applications Department Data Services
https://aa.usno.navy.mil/data/index

NOTE: The NEW US Naval Astronomical Applications Department page allows adjusting time within a zone. So you may choose between 11 hours west, 11.25, 11.50, 11.75 incrementally refining your Sunrise/Sunset predictability while on station.

NOTE: Alternate Sunrise/Sunset Calendar. - https://www.sunrisesunset.com/custom.asp - You may create your own custom calendar using Lat/Long, Sunrise/Sunset, Moonrise/Moonset for a particular Month and Year.

I use the US Naval Astronomical Applications Department Sunrise/Sunset, Moonrise/Moonset Almanac to check my celestial sphere during gameplay.

I'm releasing my findings and observations about 1x play and how it affects the synchronization of the celestial sphere when using 2018 computer hardware.
It takes a long time to make observations at 1x, but I have nearly completed a series of observations which reveal some interesting side effects which absolutely affects gameplay, even when using typical time compression. After all, we have to go to 1x when making or avoiding attacks, sometimes for hours at a time. Typically though, players will constantly use a combination of 1x and time compression during these times.

Simply put....
When playing at 1x to 1024x time compression, the game is REMARKABLY accurate when rendering sunset and sunrise! (Compared to Almanac times.) A bit less accurate when rendering moonset and moonrise. However, when playing ONLY at 1x, a cumulative error occurs which offsets the synchronization of the celestial sphere so that the sunrise, sunset, moonset, moonrise times are out of sync with the Base Time clock, even when not traveling outside (east-west) of the Base Time zone.

OK, now here is the interesting part. The error seems to be directly related to the Vertical Sync setting in the Graphics Options. When Vertical Sync is selected on, there is a cumulative and noticeable error of the offset of sunrise, sunset, etc. (when played at 1x speed. I'm observing 60 fps with Vertical Sync clicked on.)
When Vertical Sync is un-selected, (I'm averaging 240 fps), the error offset is very much greater (when played at 1x speed). The difference is in many hours over a period of a few days.
That is why I posted my original message in the FOTRSU thread inquiring why my sunset, sunrise was off by many, many hours even though I was still in my Base Time meridian range. It was dark, but should have been daylight.

http://www.subsim.com/radioroom/show...postcount=6716

I'm arriving at the conclusion that with our modern computing hardware running balls out fps, a celestial sphere synchronization error is introduced (and cumulative) that affects the timing of certain events and may answer questions about strange behaviors. When it is visually midnight, but the Base Time clock says it should be daylight, you may think you are making a night attack, but, from the enemy's perspective, it is broad daylight and they can actually see you. (Even aircraft.)

I have repeated my series of tests and my observations are repeatable.

Try this, select Vertical Sync on (requires game restart), start at Brisbane, Jan. 3, 1944, outside the harbor. Steam (15 knots) directly to the 154 deg. 0 min meridian at 1x and thence directly north on the meridian until sunset (remain at 1x the entire transit). You start at about 1300 hours and sunset will occur approximately at the predicted almanac time of 1840 at 154 deg. 0 min E, 26 deg. 0 min. S.

I've observed sunset at 1824 (middle of sunset) 1827 (upper limb set). So, slightly early. (The next morning sunrise is 30 min. late, and the following sunset is 37 min. late at 1x (15 knots, proceeding north along the meridian.))

Now do the same thing, only with Vertical Sync off (requires game restart). I'm observing sunset on 01/03/44 at the same lat. long. quite a bit later (37 minutes) at 1904 (upper limb set). This is after only about 5 hours of 1x play! After 24 hours at 1x play the error becomes significantly greater!

Now do the same thing, Vertical Sync on (requires game restart), using typical time compression (1x-1024x) and you will see that the sunset occurs within a few minutes of the predicted Almanac time. After several cycles of testing this observation, day after day, sunrise and sunset, as I proceed to my Patrol Area (Bismarck Sea), I have to offer kudos to the Original SH4 devs. Essentially, they got this right! Sunset, sunrise, moonset and moonrise are within minutes of the Almanac predictions for each different lat. long.

When I play at 1x to 1024x with Vertical Sync on, the sunset/sunrise times are remarkably accurate, sometimes exactly at almanac predicted times! I've made these observations over a period of days from Jan. 3, 1944 to Jan. 10, 1944. I have yet to run a test with Vertical Sync off and 1x to 1024x play for comparison.

So, my conclusion, so far, is that it is best to play with Vertical Sync on, which minimizes the celestial sphere synchronization error when the game is played using 1x to 1024x (I have not tested anything more than 1024x because I saw no difference between 512x and 1024x observations. I'm assuming there is very little difference when using time compression above 1024x.) The error is very apparent when the game is played only at 1x speed. The error is greater when Vertical Sync is off.

This may explain why, after a long patrol, in and out of 1x play, we see such great discrepancies from what time we observe it should be, to what time the Base Time clock aboard our boat indicates it is, especially when playing with Vertical Sync selected off.

I have a few more observations to make and then I will post my results in a somewhat orderly sequence.

I am making four discrete observational tests.
(1) Playing at 1x with Vertical Sync on making observations at 1/3/44 Sunset, 1/4/44 Moonset, 1/4/44 Sunrise and 1/4/44 Sunset.

(2) Playing at 1x with Vertical Sync off making the same observations as in (1) above.

(3) Playing at 1x-1024x with Vertical Sync on making the same observations as in (1) above.

(4)Playing at 1x-1024x with Vertical Sync off making the same observations as in (1) above.

I would appreciate any others who wish to duplicate this series of tests in order to see if my observations can be duplicated.

Thanks!

[EDIT] See linked post....
http://www.subsim.com/radioroom/show...67&postcount=8


[EDIT] When using the US Navy Complete Sun and Moon Data Almanac, or, the Sun or Moon Altitude/Azimuth Table, when you are based out of Pearl Harbor, use ""11 hours west" of Greenwich"" to obtain the correct Base time (ie Sunset), and, when you are based out of Midway, use ""12 hours west" of Greenwich"" (ie Sunset) to obtain correct Base time.

See top of message for US Navy Link
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"Only the dead have seen the end of war" - Plato

Gone but not forgotten, RIP Dave "LeoVampire".

Last edited by Front Runner; 09-23-22 at 10:10 AM.
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