Celestial Navigation in SH4

[I'm goin' down]

thanks. I still need help tying stellarium to SH4 training mission. I installed stellarium. Man, that is an amazing program. And I thought the mega mods were good!

[Diopos]

(BTW it's DiOpos not DiPpos)

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[CaptainMattJ.]

i dont get what erxactly this mod does.....? Are you talking about navigating with the stars only? if so, then you should be able to see your sub like you normally would at night, and at day you cant see where you are. thats how they did it back then. all they had was the stars to navigate, and stars can only be seen at night. therefore, it should be a simple (maybe?) mod in the folders. when its take sub marker off map. at night put it back on.

[Pisces]

Originally Posted by CaptainMattJ.

i dont get what erxactly this mod does.....? Are you talking about navigating with the stars only? if so, then you should be able to see your sub like you normally would at night, and at day you cant see where you are. thats how they did it back then. all they had was the stars to navigate, and stars can only be seen at night. therefore, it should be a simple (maybe?) mod in the folders. when its take sub marker off map. at night put it back on.

This mod (actually, it is not in any way a mod-ification, as nothing in the game itself gets changed) gives you an external way to (accurately) simulate measuring the height of celestial objects. The sextant mods sofar made for SH3 and SH4 are just to crude to be usefull. With those measurements you can calculate where you are in the world.


Which star can you also see during the day? Does it not rise and set?

But seriously now, you should also be able to use the planets and moon as targets to take fixes from. If the almanac or ephemerides contains their positions. It's just easier to use the stars as they do not move on their own. Well, not measurable for this purpose anyway. Planets, sun and moon move a little bit every day, so you'd have to recalculate (extrapolate) their position in the heaven every new sighting you do.


The game stores the location of the sub in the savegame (in name_of_savegame.map). The python script reads this location and converts it to a latitude and longitude coordinate for Stellarium. The python script asks for a time and date (as I don't think it is stored in that file, though it must be hidden somewhere I'm sure, but nobody found it) and should generate a Stellarium startup script for it. Actually, to make it work you do not need to enter the time and date of the game. Your current time and date also works, it's just not immersive as you'll see a different sky. In Stellarium you measure the altitude (height) of 3 or more celestial object in question and afterwards you do the numbercrunching (mostly using tables) to develop your position plot. The celestial object positions are in the almanacs that 6SJ7GT generated for those years, or you can use the link I provided some time ago (my last message above) to the new USNO online almanac.

You'll have to keep track of your own movement inbetween skyfixes yourself through the use of deadreckoning. Meaning, plotting your movement on the map based on your speed and course. Whether or not the sub symbol is shown on the map is optional. I don't even think you can switch it on/off at the change of redlight (sunset and sunrise)

[I'm goin' down]

I need a walk through to get set up. Here is where I get lost.

I have installed SH4; and
Opened the Stellarium file on the C drive;
Inserted the file changes to Stellarium directed by the tutorial; and
Started a mission in Sub School (the navigation mission)

When I opened Stellarium the dates are the current date. What file do I open in SH4 (or Stellarium) to insert the the correct dates, longitude and latitude, etc. soo I end up at the right location, date (1943) in the Navigation mission, and, I assume, in Stellarium so when Stellarium is running, it is not opening on the current date? If I have to insert the 1943 date in Stellarium, are you advising that every time I use the program I will have to reenter the date for the 1943 date, or can I save it somehow?

Once the above is corrected, what other downloads will I use on the first tutorial. Stellarium, the Stellarium pdf., and the SH4 tutorial pdf. are the only things I have download so far. I didn't want to download the other items right off the bat, as I did not know when and if I would need them.

[Pisces]

Originally Posted by I'm goin' down

I need a walk through to get set up. Here is where I get lost.

I have installed SH4; and
Opened the Stellarium file on the C drive;
Inserted the file changes to Stellarium directed by the tutorial; and
Started a mission in Sub School (the navigation mission)

When I opened Stellarium the dates are the current date. What file do I open in SH4 (or Stellarium) to insert the the correct dates, longitude and latitude, etc. soo I end up at the right location, date (1943) in the Navigation mission, and, I assume, in Stellarium so when Stellarium is running, it is not opening on the current date? If I have to insert the 1943 date in Stellarium, are you advising that every time I use the program I will have to reenter the date for the 1943 date, or can I save it somehow?

Once the above is corrected, what other downloads will I use on the first tutorial. Stellarium, the Stellarium pdf., and the SH4 tutorial pdf. are the only things I have download so far. I didn't want to download the other items right off the bat, as I did not know when and if I would need them.

Did you use the latest version of this 'mod'? Check this message:

http://www.subsim.com/radioroom/show...6&postcount=52

[I'm goin' down]

I have the most recent pdf downloaded.
Here is what is says re installing, followed by my questions.

We will use the Navigation Mission in Submarine School for this introductory exercise. Start it up and look at
the map, you will see:
Starting Position:
Lat (L) 5o14’N Long (λ) 162o57’E Time 11:00 (21:00GMT)
End Point (Gold Star, Nav Mission Goal)
L 6o24’N λ162o59’E
You will need to install the freeware planetarium program Stellarium. http://www.stellarium.org/
After installing start the program so it creates a config.ini file. There should be a link to this in the Stellarium
startup directory, if not you can find it under C:\Documents and Settings\***Your login name***\Stellarium.
Open this file and find the [localization] section. Change time_zone to =utc
There is a directory called Scripts under the Stellarium program directory. there should be a file called
“startup.sts”
Paste the below lines into the file:
date utc 1943/01/01T21:02:00
moveto lon 162.960510583
moveto lat 5.23516041667
script action end
This is the information the python script gathers from the SaveData.map file and puts into Stellarium. There is
no modification of the game with this technique.

I cannot find the follwing:
After installing start the program so it creates a config.ini file. There should be a link to this in the Stellarium startup directory, if not you can find it under C:\Documents and Settings\***Your login name***\Stellarium.

I have no idea where the Stellarium startup directory is located. I cannot find a file called Documents and Settings in my C drive. I had all hidden files showing when I search for it..

[Pisces]

Then you probably have Windows Vista or Windows 7. The user profiles are stored in the folder "Users" instead of "Documents and Settings".

You should find it in: C:\Users\_Username_\AppData\Roaming\Stellarium

[tomoose]

I've been reading the posts here about celestial navigation and as a complete novice at that art I was curious about how accurate the game would be (i.e. are the stars where they are supposed to be, when they're supposed to be).
I was on patrol off Formosa on 14 June 1943 and headed due South. I noted the time (0010hr, in-game) and took a screen shot (on the left below) of what stars I could see due South.
I then used Stellarium and placed my start point as Taipei, Taiwan (aka: Formosa back in the day) and trying to correct for the time discrepancy in-game I sought to duplicate the time/date from the game (i.e. Taipei is 8 hours ahead of GMT ergo I used 14 June 1943 at 0810hr). Below on the right is the Stellarium screenshot.
It's hard to see the stars in the SH4 shot due to the size restriction of the graphic and the fact that the starfields in SH4 are not as bright and as obvious as Stellarium (is there a modded brighter starfield out there,LOL?). If you look close you'll see the similarity of the constellations (I numbered some of them for clarity).
Result? Pretty damn close allowing for the fact that my sub isn't parked in Taipei harbour etc, LOL. Again, I say this as an easily impressed novice, LOL and perhaps one of the experts will correct me if I'm out to lunch here. Having said all that I'll have to find an online tutorial and figure out how this works!!!!


EDIT: I just noticed that Stellarium shows 13 June vice 14 June but I'm assuming that the stars would still be in the same general location 24hrs earlier or later so I believe I can retain my "wow, cool" sensation!?!?! yes? no? LOL

[I'm goin' down]

I get an old pogo stick. When I get high enough, I check the sky. When I return to the driveway, I run inside and compare what i have seen to Stellarium. I saw Vega. What this? Jody Foster was walking on the beach?
(Why is that van outside bearing the emblem of Happy Dale Sanitorium?)

[I'm goin' down]

Originally Posted by Pisces

Then you probably have Windows Vista or Windows 7. The user profiles are stored in the folder "Users" instead of "Documents and Settings".

You should find it in: C:\Users\_Username_\AppData\Roaming\Stellarium

Okay. I found the file. The localization file was preset to the correct entry, so there was nothing to adjust. I already changed the Stellarium program directory and instructed. Now what. When I open Stellarium, it still shows my location at home where I set it the program to run and uses the current date. What do I do now? Insert the date, time, long and latitude for the practice mission? Are SH4 and the program linked? Or is the sky in SH4 real time (1940 and 1945 and you use Stellarium to figure out where your are and how to plot where you want to go, and then return to SH4 and plot it? I do not have an overview of what is supposed to be done.

[tomoose]

Has anyone done any research into improving the "look" of the in-game night sky (i.e. the stars/constellations) in order to aid in celestial navigation? I'm not talking adding more stars but making the key stars more obvious. Is there a dat file or something whereby you can increase brightness et al? Just curious.

[Pisces]

Originally Posted by I'm goin' down

Okay. I found the file. The localization file was preset to the correct entry, so there was nothing to adjust. I already changed the Stellarium program directory and instructed. Now what. When I open Stellarium, it still shows my location at home where I set it the program to run and uses the current date. What do I do now? Insert the date, time, long and latitude for the practice mission? Are SH4 and the program linked? Or is the sky in SH4 real time (1940 and 1945 and you use Stellarium to figure out where your are and how to plot where you want to go, and then return to SH4 and plot it? I do not have an overview of what is supposed to be done.

I suspect you followed the steps shown on page 1 of the pdf document? Well, the way I read it it is just a description of how you would adjust the location in the file by hand. This isn't really the way to go every time you want to do a starfix. Instead, start with the descriptions on page 5. You need the python programming environment and adjust some lines in the python-script that 6SJ7GT wrote. (every time you go on a new patrol because the savegame folder path changes) Then you can run that every time you need to do starfixes. It wil ask time and date of the save game and it starts Stellarium automatically, and should be with the right location and time.

[Pisces]

Originally Posted by tomoose

Has anyone done any research into improving the "look" of the in-game night sky (i.e. the stars/constellations) in order to aid in celestial navigation? I'm not talking adding more stars but making the key stars more obvious. Is there a dat file or something whereby you can increase brightness et al? Just curious.

I remember someone here (in one of the celnav related threads) wrote way back that the stars are only pixels plotted on a rather small sphere around you. Not proper lightsources that are drawn at infinity. So that would imply you'd even experience some parallax error in your directions if you used them ingame.

[Munchausen]

There was also an old attempt at "improving" the look/brightness of the stars. IIRC, they came out diamond shaped when enlarged.