New Astronavigation Mod (ANM) – A Conception

[Vanilla]

Accorind to my measurments the sun does not follow a real-world pattern (or any sensible pattern for that sake) on the SH5 skies, you can see it for yourself using sextant from TDW UIs mod. This invalidates the whole sky height measurement process. More to that there is a strong possibility that the sun position is dependent on the screen resolution. Even if there is a pattern, I doubt it is possible to see the horizont and the sun simultaneously given the tools we have.

[silent marshal]

@ Vanilla: you're exactly right: SH5 doesn't reflect realistic sun behaviour. The process I use is totally independent from SH5 and that's why it works absolut correctly. There must only be a script which prevents the use of the sextant-UI at heavy weather when the sun can't be seen (or at night of course) - but this for realistic gameplay only.

The crucial point of the process ist this:
If you know your exact position, you can calculate the hight of the sun. I do this as the first step (using SH5's exact position data which the player doesn't know) and now you can calibrate your sextant's scala this way that the (dummy) sun touches the horizont with the exact angle - and this for every second of a year.

See the result below: delta [Pos] ist the distance from the exact position of SH5.



I make some tests and the results are awsome. Depending on the accuracy of your input data your graphically located position is in a radius of a few hundret meters (well only if I use the exact calculation values; for real life conditions the accuracy will be 1km up and more - like it is in real world navigation).


I forgot to upload the nautical yearbook which will be written by a routine for a 1-hour period depending on your data input on the sextant-UI.



Here only the period from Minute 00-30 is shown. There will be a second page with the second half of the hour. Still in progress.

It works pretty well, belief me!

[urfisch]

very interesting stuff!

[Vanilla]

Oh, I see now! Sorry for being dumb in the first place. That's a very interesting idea!

[don1reed]

Excellent work, silent marshal. Very much looking forward to try it out.

[tonschk]

Indeed very intresting

[quink99]

As one who has done a bit of RW celestial navigation in both sailboats and aircraft this would be the ultimate in immersion, challenge, and fun.

My congratulations, Silent Marshal! It won't be easy but it will be worth the effort. Good luck!

[ETsd4]

Originally Posted by silent marshal

It works pretty well, belief me!

Sorry to say that, but that's not true.
A "graphical solution" for finding the FIXposition depends on Length/distances and arcs. The SHunter-world has different distances and different arcs. THere is a mismatch between the varying mercator-projection of the real world and the constant mercator-projection of SHunter.
The only places where SHunter and the real-world is fairly equivalent is near the equatorial region (real world= 60nm, SHunter= 64.79nm). There will be never ever a "graphical solution" you will draw with SH5 map-tools which your picture implies here ...

[silent marshal]

Originally Posted by ETsd4

Sorry to say that, but that's not true.
A "graphical solution" for finding the FIXposition depends on Length/distances and arcs. The SHunter-world has different distances and different arcs. THere is a mismatch between the varying mercator-projection of the real world and the constant mercator-projection of SHunter.
The only places where SHunter and the real-world is fairly equivalent is near the equatorial region (real world= 60nm, SHunter= 64.79nm). There will be never ever a "graphical solution" you will draw with SH5 map-tools which your picture implies here ...

Hello ETsd4!

Thank you for your critical comment. You figured out, what is the difficult part of the problem. It seems that SH5 uses some sort of UTM (Universal Transverse Mercator) coordinate system. That means, that the higer to the north or south you are, the mote distances (width only) are streched. You can check this when you compare distances from SH5 with the ones in google earth. (I know, you are firm with all this, but maybe there are some readers who aren't.) For simming this means that you are travelling a greater distance as you would do in real world.

I have factored in this fact and that's what the "Horizontalversatz" is doing: it corrects the sphere/plane geometry of the "Höhendifferenzmethode" to the UTM system.

How my method works:
The calculation bases on a spherical system. Because of the great distances, we can transform it to a plane system, where circles are lines - that's what you are doeing in real world also. I can do this at the nav-map but consider not the coordinates of default SH5. Now I have to transfer the intersection point - which is the exact position at the sphere - to UTM of SH5 and this is done with the "Horizontalversatz".

I will make some more tests but I wonder if there are any errors left.

Critical comments always welcome! If I am wrong, ashes to my head and I will submerge into the deep of www. If I am right, SH5 will be more exciting.

[don1reed]

Both SH3 and SH4 have MapFiles. In SH3 it's located:

C:/Documents/SH3/data/cfg/Careers/skipper's name/0/_____.Map

In SH4 it's located:

C:/Documents/SH4/date/cfg/SaveGames/00000000/SaveData.Map

There isn't a "Map File" for SH5. (That I know of.)

An amateur mathematician, Celestial Navigation Enthusiast and practicianer; not to mention, an all-around nice guy, Michael Jones, created a script file using Python and Stellarium to take the data from the SH4 Map file and convert the numbers found therein into Geo Coords. Numbers such as:
-1198199.13, 6006413.50,0.00

by dividing these numbers by 120000.

i.e., -1198199.13 / 120000 = -9.9848993. The (-) sign indicates West Longitude and South Latitude. The quocient then becomes: 9°59.1'W.

6006413.50 / 120000 = 50°3.21'N.

Everytime a "save" is done on your computer while playing, it auto-updates your true position on the game chart, even if your boat's icon is hidden.

Alas, SH5 does not have a MAP file that I know of.

And, of course, the Python/Stellarium method of celnav was used because the celestial canopies in SH3 and SH4 are not accurate, whereas, Stellarium's canopy is true.

Once Python obtained your true coordinates, it pulls up Stellarium and presents the correct celestial canopy you would be viewing if you were in fact, at that location. All that was left to do was to take of round of virtual sights of altitude and azimuths of selected bodies and have Nories, or HO Pubs 211, or 229, or 249 and almanac at hand to do the sight-reduction...five times per day, as in real life.

Then again, the next problem was the matter of the Mercator Projection Chart. None are true in the SH games. They're charts meant to fit the resolution of your display. So...forget Dead Reckoning as well.

When Navigators purchase charts from authorized chandlers, the charts they buy are printed to very precise specification and are miniature ratios of the real world, i.e., 1:1,000,000 scale. This is an extremely precise ratio, which means it is accurate to the length of one Toyota Prius to 1M Prius, or 1 nm to 1M nm, or 1cm to 1M cm, etc. One could say it's etched in stone. The chart in these games...not so much.

Edit: I'm looking forward to see this come about and wish you great success.

Cheers,

[Nico71]

After so many attempts to get real nav to work in SH by the community - with variing success - I'm inclined to give up on it. I did it successfully in FSX, with sextant, weather ships and whatnot. That being said, I really hope that you get this to work! That'd be really awesome!

[Sartoris]

Sounds like there are some problems to overcome, but man, it would be so amazing if you could pull this off!