When sonars are sufficiently powerful that they can make bottom bounce detections or convergence zone detections then you need some kind of model of how sound travels in the ocean. In the second world war, from what I've read, they mostly only made direct path detections. If I recall correctly, the big advance of the SQS-26 over World War II sonars was that it could make bottom bounce and convergence zone detections.

If all one is worried about is direct path energy, though, then "cookie cutter" range laws are fine with detection.

Yes, we're probably saying the same thing here. My point is that even a "range only" model should be more realistic and not allow contacts to be heard from 15 nm away no matter the conditions. Also, the inclusion of surface noise wouldn't be bad either.

I like SH3 but I love DW
Nedless to say, but I always learn something new from you people and the excellent discussions in this forum.:up:

I could take it or leave it, honestly. In WWII sonar was so crude that it's not really clear how you would deal with much variability. Additionally, there was very little (if any) real attention to quieting. Everything was loud loud loud. That was an age where there were barely even industrial regulations on noise levels, let alone stealth considerations. You only really need to worry about the details of ambient noise or whatever else when the signal gets down near that level.

The Germans were the first to really start thinking about how to make their boats quieter. The innovations they sparked didn't really have an impact until after the war, though.

I can see that you have quite a strong opinion when it comes to people complaining about sensor accuracy or demanding more from the sim. Your arguments surely make sense and since I agree that having a tactical mind is the key to sims, I will leave it at that. :ping:

"In tactics, the most important thing is not whether you go left or right, but why you go left or right" A.M. Gray

Well... the thing is... I'm not sure that including more and more details for the sake of adding details is giving you a better simulation. I suppose for a certain type of techno weenie it is, but I'm not that person.

The thing about all simulations is that their instructiveness tends to hinge on whether or not they capture the essentials of a given phenomena. My experience in both professional wargaming and in the hobby is that there is too much emphasis on including every little detail. None the less, as computers have become more powerful, it seems like the tendency has been to include greater and greater detail simply because the computational capacity is there. The thing is, I've spent many many days tweaking the knobs on these sorts of simulations with every gorey detail in them, only to discover that they didn't matter anyhow, usually for a good reason. A simpler model usually would have sufficed, and provided more insight more quickly. Often the values associated with the knobs in question are subject to such great uncertainty that it's questionable whether one can quantify their impact anyhow.

What I do wish they would do in computer simulations is make them more transparent. I'd really like them to say in the manual, "here's how we decided to model our sonar," for example. From what I can tell in DW, for example, it really just generates a very simple family of transmission loss curves, but it took someone else's experimenting to figure it out. If they made it more transparent, it'd be easier to figure out exactly what the scope of the model was, so one could make scenarios that were more challenging, given what it represents. I don't really care what assumptions they make so long as I know what they are and I can work with them.

:yep:

The only thing about that SeaQueen is, and I'm sure you're aware, is that if they even got a small fraction of anything classified in their sonar model the US Navy and any other nation they provided software for will have them for lunch.

This has been my stance eversince Sub Command and DW's early start. We don't know how much classified material they used for any of their modelling and can't make judgements as such.

DW sound simulation is deep in public area of knowledge. At the moment I could write the same simulation myself based of my measurements (although there may be details I missed, like recently discovered bottom type influence). I mean I could do that in a weekend, it really is simple. My sound propagation utility, based on public information (Ulric's book mostly) has all DW has (minus bottom) and much more.
Simply said .. sound propagation is public, including methods of simulation. Well maybe they have some super-simulation somewhere used for sonar design and so .. but DW is not in this class, by a big margin.
Classified things may be actual noise levels of ships, and sensor sensitivity, lets say 'parameters of actual military warfare' .. but that can be seen from the game itself.

Btw. don't get me wrong. Since 1.04 I think DW sonar modeling is more or less appropriate, considering how many receivers it can simulate in real-time (sonobuoy fields I mean).

Hm .. I thought about it .. why would I not make my sources public .. here are some reasons:

- I can't. Some contract does not allow that. For example I buy some module, I extend it, so it is crucial part of my new product. But I usually can't make public what I bought somewhere, even if I modify it.
Edit: also often when you do your project for someone (the navy), then use the same sources for other project (game), you are usually not allowed to make it public.

- I don't want to. For example I still use that code for my other projects, which I sell.
Also exposing your source codes is like exposing your soul. Also most source codes looks terrible and are far from 'how source code should look like', even in projects which are open source from beginning.

- I don't care. Making sources public .. why ? Will it make my name better ? Better than 'army contractor since 1973' ? Will it bring us more money, more projects ?
Isn't making naval simulation source codes public even in conflict with security policy of the state ? Should we risk it ?


Now all that could apply with SCS. Adding new playables would be little different. It could be trouble, if they plan to make DW 2. But if they don't plan (as I think), there is no reason for that anymore. They could allow that. Only difference would be that those mods, which exists I think, would be posted here, and would meet more audience.

SCS could base DW 2 on a totally new codebase, keeping secret the core engine while at the same time providing modding tools for inserting new models, new database entries and why not a plugin architecture so that for instance the graphics engine is decoupled from the core naval engine.
Keep the secret stuff secret for their institutional customers, and let the game community have access to "public interfaces".
But this will never happen since all their games are based on the same old old old last century old code. :nope:

I don't see how something "classified" could be allowed to reach a commercial market, especially from a military contractor (who plays by the rules). It all looks more like marketing strategy or business arrangements between the companies that brought DW to the market (its not just SCS).

Instead of a conspiracy theory about secret hidden codes maybe we should just accept the fact that business decisions are made according to profit and government contracts are more promising than computer games.

So, just another product that gets abandoned. It has happened before.

OH PUH-LEASE!!!! There's nothing classified in DW. If there was, everyone here would need a clearence, and your hard drive would be stored in a safe. You couldn't play DW over the Internet either, you'd have to use the SIPRNET. Oh, and the window behind your computer? You need to put some blinds on that. And nobody talk about the game, for heaven's sake without turning on the white noise generator! That'd be a classified conversation. People have been saying things implying that a given subsim contains classified information since Microsoft's Red Storm Rising. They didn't have anything then, and they don't have anything now.

Somehow, they draw on a small family of TL curves and use it to compute a very simple signal-to-noise ratio. There's nothing classified in that. Even the Navy's official sonar models are unclassified. At most they're maybe FOUO. The database feeding values into them is the classified part. Here's some screenshots of their sonar models:

http://www.d-a-s.com/imat.html

Hmm .. this terrain influence sound propagation .. looks more interesting then I expected :hmm: I wonder if this could be done realtime. Will try, you know me ..

Sound in the ocean is REALLY complicated. People in video-game land don't always seem to realize it, though, because they have ray traces stuck in their heads of convergence zones, surface ducts, and bottom limited environments. The thing is, ray traces are not the best way to model sound in the ocean. They're only really good for relatively high frequencies and they don't really take into account things like interference.

What you really need to do is compute the normal modes of the parabolic equation. There's different algorithms for doing that. There's a book called Computational Ocean Acoustics which is all about just that.

Most of what you see on the web page is a graphical representation of transmission loss as a result of computing the normal modes of the parabolic equation.

As for real time.. it really depends on what you mean by real time. Once every few minutes? I think you could do that. I doubt you could use the parabolic equation for a video game, though. It would take a lot of horsepower. It'd be neat if you could, though. People would definitely find it a lot harder to estimate how far they could see because it could vary so much for no obvious reason.

Hmm .. this book is on google books . Awfully incomplete, as usual. You cost me a lot SeaQueen, you know that ? :rotfl:

Well I know raytracer is not enough. But I'm having troubles finding the differences. Let's say comparison between raytrace and other methods, on pictures, side by side.

For the game all this level is not needed. We just would use some of the features, like fluent changes (compared to steep changes), changes in time, sound channel, more effects of the bottom in active sonar, and some other stuff.

First we must select what effects are important and needed. Then we can talk about how to do it. I can do the later. I hope you SeaQueen will help me a bit with the former.

:doh:..okay.

Now can we enhance the passive sonar detection capability:rotfl:

According to most publications, RL detection range is far shorter than in DW now. So, NO.

Really? I just tried a test with DW. This time a Type 42 DD at 2900 yards only shows up as thin line in 688i's normal BB. I went to NB to try to classify it and it was classified as either 2 torpedoes...weird.

In the end the DD detected me much faster than I did and launched 2 torpedoes at me missing me because I was too close.......

So I say most publications LIE:D. DD more quiet than a sub?

I have some screenies but too lazy to put them:rotfl:
I was travelling at 5 knots bottom at 9,000 somethin probably feet. No thermal layer.

The biggest difference I've noticed is that raytracers tend to be pretty good approximations for TL in the thousands of Hertz range, and awful in the tens and hundreds of Hertz range.

There's also some lecture notes that go well with that book on MIT's OpenCourse website.

It's like I said, the phenomenta that are important are frequency dependent. The sonic layer depth might matter a lot for a sonar operating in the thousands of Hertz band, but have an almost immeasurable effect on a sonar that operates in the hundreds of Hertz. How to capture that in the game, is tough, though, because you'd have to solve the parabolic equations somehow (See the book I recommended).