Obtaining accurate speed estimates from map plots
 

I'm a 100% realism player. That means absolutely no map contact updates to form torp solutions. When I use the stadimeter to obtain two range/bearing readings, then click the clock icon for speed/course, I usually get values that are off a good deal in accuracy. So unless I'm firing from close proximity, I don't have very good hit percentages. Now when I use map tools to plot stuff, there's a margin of error there too, which doesn't affect the course so much as the differences in range throws the speed calculations way off. Is there any way to obtain accurate speed estimates?

How much time do you allow to pass between readings? I think that the estimate is better the longer you wait between readings.

If you're plotting it out, use more than two data points. I usually get a fix at 0:00, get another fix at 3 minutes, another at 6, then 10 minutes, with a fix every 5 minutes afterwards. If I detect a zig, I start over with three minute plots. I usually base a speed estimate on 15 to 20 minutes of plots.

I also enter everything into the TDC, and check to see how well the data matches with observations. If you've got a good idea of his course, that can help you refine the target's speed. I don't know what mods you might be running, but I love the 3D TDC mod for this.

I would go along with what razark said. I use multiples of 3 min. as this is convienent. That is 6 or 9 min. intervals when the target is distant or you have plenty of time, and 3 min. when the target is close and you intent to shoot soon. The clock button inaccuracy is a known issue; I never use it anymore. The visual plot is, as you found out, is subject to error. It was the same way in real life. I would think in terms of half a dozen to a dozen points for a plot. IMO, you can't expect a good level of accuracy, from 2 or 3. Really, a good plot is part art, and part science. It is also desirable to be able to make visual estimations of the AoB, and not rely entirely on stadimeter ranges for your plot.

Agree with this 100%. This, I believe, is one of the things that made the TDC such a powerful tool.

agree with the other comments.

In addition, when trying to manually plot a manual solution, it is important to use all the tools available in game to double check your results. For example:

-manually plot target bearing/distance on map and use game stopwatch to calculate speed. Crosscheck against speed estimated by TDC stopwatch;

-after you input your solution into the TDC, track target using scope/sonar and see if it matches with the TDC.

If the results are close, you are on the right track. If they don't, go back and recheck everything.

Also don't forget to use your common sense, if you calculate a speed which is unusually low or high, i.e. a freighter moving at 17 knots, there is a good chance you made a mistake somewhere.

Hi, gi_dan. I was just answering another post of yours when I ran across this one.

I too am a 100% realism player. I learned back in my SHIII days how to plot contacts on the map with no help from the computer. Thanks to guys like Wazoo who developed the process of map plotting using a hand held tool similar to my AoB Calculator found HERE. The difference in the calculator Wazoo used and the one I developed, is a third "compass" dial that helps in turning "relative" bearing into "true North" bearing. If you're playing the German side, the calculator is extremely important in providing an accurate plot on the nav map. On the American side of play, knowing what the Position Keeper/TDC dials do and how they relate to one another takes the place of a hand held calculator.

To be brief, I won't go into the details of explaining what the PK does, how to use the dials to plot a targets position on the nav map, or use the plot to estimate speed and AoB. But, my "High Realism Tutorial" does. It's showing it's age (I should update it to comply with the work I've done with the Optical Targeting Correction mod) however, the process of making a plot and making a good firing solution from it still holds true.

One other quick point, my first frustrations with the game came when I discovered (much like you), why was I missing a target after doing a fairly good job in making the estimates required to complete a firing solution? I found out the games target mast height measurements were not even close to what they should be. Some so far off, that at a true 1200 yard distance the stadimeter would read a 500 yard error into the range figure! Some of the problems are indeed due to what I've discovered through the Optical Targeting Correction thread where I've pointed them out (like the stadimeter not being centered on the sub; allowing a 10 to 20 yard difference in range finding, in less than 1000 yards distance, depending on which direction the reading is taken. The error growing much larger, the further away the target is). But, the mast heights are really the problem with many of the Recognition Manual entries.

In my opinion, I'll accept a miss due to realistic running torpedoes, or a calculation error I put into my plot, or estimated data. But, to have the game measurements so far off that the only way you could hit some of these targets is to be close enough to ram it shouldn't be one of them. It's like going into a gunfight, knowing your weapon shoots to the left by twenty feet. Not realistic at all.

I use this formula .. lenght of the ship / sec on the clock X 1.9 = speed of the target ship . However the stock book does not have data about the lenght of the ship . So I have been asking for information if there is a Mod that has better data in sh4 .. I play sh5 and The SOAN book has this contained in the recon, book :damn:

I noticed you asked the same question in another thread, but I'll answer you here.

Yes, Optical Targeting Correction has the length of the ships in its Recognition Manual. The correct height and lengths are both given in the RM. OTC doesn't rely on using the mast height for determining ALL ships height. Some, as the following image shows, use the funnel as the stadimeter "reference point". Some other targets may use it's national flag as its reference point, or the top of its bridge; all ships are marked with a red pencil at its reference point, or have its national flag added to the picture to show where the reference point is.

http://i175.photobucket.com/albums/w.../AoBTest_1.jpg

As I pointed out earlier in this thread, just adding heights and lengths isn't enough to correct some of the inconsistency. Optical corrections need to be made to allow heights and lengths to measure accurately. If 3 feet doesn't add up to a yard then what's the purpose of having heights and lengths added to the game? They won't matter if the dimensions can't be measured in an accurate way.

First off I appreciate the useful knowledge of people on this forum. I believe subsim.com is well moderated and has an excellent, professional, and polite user community. Not many can boast the same. Now to personally thank you, CapnScurvy for taking the time to answer my questions in the most efficient and timely manner possible.

Your suggestion makes absolute sense as to why I cannot obtain accurate measurements with the stad/dials, since the error margin increases exponentially with every yard of distance.

Thank you for that formula. I will log it into my notes. This is also the fixed wire method correct? Do I have to be stationary for this to work?

One of the things I loathe the most about SH4 is its inherent sloppiness of engineering and programming. Ubi clearly was not focused on accuracy at all. IMO I feel that they made the game under the guise of "simulator" but actually intended it to be played mostly with auto-targeting turned on. With that in mind, that's why I feel they took little effort in actually making the measurements correct for manual targeting. On the note of going into a gunfight knowing your weapon shoots twenty feet to the right, sadly enough, some people would be that ill-prepared. :shucks: DRAW! :shucks:

I usually take a reading every 5 minutes or so if I have the time to do so. I then add up the total reading time over the total distance to gather accurate info. I once laid waste to a small single-string convoy of three targets by observing them for the better part of an hour over radar.

Now my next question though... Unless I play with map contacts on (which I really hate to do) I notice that the built-in error margin on the map measuring tools throws much of the information off for the solution, especially speed. This is a pain in the rear for sure :-?. Now if I can't rely on my map tools, and I can't rely on my periscope and my stad/dials, what can I rely on? Active and passive sonar? Give me a break, I don't want an early watery grave :dead:

Believe me, this is a dead horse around here. We've chewed this topic so much, our jaws hurt. I don't blame the developers at all. They had a project of turning a German campaign into an American one, with the producers (UbiSoft) expecting it to be a simple transformation. A deadline was set by UbiSoft to start profiting from SH4, and they held the developers to that date, ready or not. I believe UbiSoft had planned all along to update SH4 with the German Missions files. They figured patch 5 was good enough for the "fixing", now let's bring to life files that were laying dormant in the game, and add a few mission files. UbiSoft's plan to squeeze out a bit more money from us sub loving junkies was probably planned well before the spring 2007 release date. They made money off our expectations of the "next best thing", which turns out having more loop holes than a New York lawyer.

To give the developers credit, they realized they hadn't finished what they had set out to do. When the game was first released, this American Campaign used only metric measurements!? No feet or yards, all metric. This was corrected with patch 1, no sooner than the game was released. It however spoke volumes of the rush to release a product that wasn't ready. Most all who bought it KNEW this was so, within the first few minutes of play. Eye candy, we got a boat load. Completed details, where hard to come by.

You mentioned the error factor that's built into the measuring tools on the nav map. I'm assuming you're referring to the ruler tool that only produces a measurement every 50 yards. If you check, the measurement is very accurate at the point where the dimension changes to the next 50 yard figure. The tool holds this figure until the next 50 yard increment, before it changes again.

To be honest, this really isn't too bad considering what the original game provided. It was either patch 3 or 4 that the ruler tool changed measurements to read in yards instead of 10ths of nautical miles!! Yep, 10ths of nautical miles. Who the heck figures measurements in 10ths of nautical miles?? To give credit to the developers, who used to look-in on us here at the SubSim forums. They heard our calls for a better measuring tool and changed it to what we have now. Believe me, you don't want to use nautical miles for measuring a simple distance.

To the point of figuring distance with the ruler; knowing the "spot" where the measurement in 50 yard increment changes, and estimating where the next 50 yard measurement change will be, can put you fairly close to what can be considered an accurate measurement. It's not perfect, but as we used to say, "close enough for government work"!

-Yes I understand how they basically copy/pasted SH3, made a few tweaks, and bam! SH4. This is apparent in the non-active German ports in Vanilla SH4 v1.4. You can hear the ghosts of the German band playing as if it was SH3. When I saw that, I just started laughing because it had then dawned on me as to what they had done. They were trying to squeeze more juice out of the same orange.


-Well what gets me is the bearing dial that's centered around the sub in TMO says one distance while the ruler says another.

Re question answered
 

DGiDan yes you must be stationary , the average speed of merchants is between 5-12 knts , Now warships are a different story , This is a very quick method .. Very accurate indeed ! I suggest that you have a caculator near your desktop/laptop . to get the quick results .

Here you go:
Slide Rule Targeting for SHIII/SHIV

A method that requires nothing more than a pencil, a scrap of paper, and a stopwatch. Oh, and a slide rule. Everyone has a slide rule, right?
(There are some links to solve that problem.)

The thing I really like about this method is that it not only works, but it is a method of doing it with physical tools. No drawing on the map to do. It doesn't rely on an in-game re-creation of tools, you can do it with the actual tools available to the real skippers in your hands. You give it time, ranges, and bearings, and it gives you everything else you need to enter into the TDC to hit your target. Toss in a real stopwatch, and targeting the enemy is a completely new game.

Build your own Submarine Attack Course Finder Mark I Mod. 3:
http://www.hnsa.org/doc/attackfinder...ca/iswas-1.bmp
http://www.hnsa.org/doc/attackfinder...ca/iswas-2.bmp
http://www.hnsa.org/doc/attackfinder...ca/iswas-3.bmp
http://www.subsim.com/radioroom/showthread.php?t=106923

The manual for this device:
http://www.hnsa.org/doc/attackfinder/index.htm

Use a slide rule online:
http://www.antiquark.com/sliderule/s...lide-rule.html

Go buy your own:
http://www.thinkgeek.com/gadgets/tools/be12/

Yes, slide rules. Slide rules are awesome. Slide rules raised skyscrapers, launched ships, and landed men on the moon.

You only need to be stationary if the periscope is turned away (not exactly on) from 000 or 180. If it is pointed straight ahead or aft then your speed has no influence on the result! This does however require that you turn your course to a little bit infront of the target. And it is best to be submerged, as the sub is less likely to make course deviations due to wave action. Turning is definitely a no-no.

As you can see there are several ways to figure speed using various tools (Slide rule, calculators, specific formulas, the Nomograph). All can do the job, and all are accurate enough for a firing solution. Lots of different ways to immerse yourself into reality play.


Yes, you're quite right.

Depending on what game resolution/aspect ratio you use the Navigation Map Bearing Tool will NOT provide accurate measurements. Below is an example of the TMO Bearing Tool.


http://i175.photobucket.com/albums/w.../1000yards.jpg


The image clearly shows a ruler measurement of 1000 yards being taken (always measure from center to center), with the overlaying TMO Bearing Tool having the target centered on the 800 yard line. The ruler is the accurate measurement.

This illustrates two things.

1. The problem the game has regarding adjusting it's resolution/aspect ratio settings to provide the same optical size (which throws off dimensions and measurements) for all possible resolutions. They are different. This illustrates why Optical Targeting Correction is needed for the periscope's/TBT optical views. The same problem exists; of not rendering an image (the scope views) correctly for all resolutions.

2. Attempting to use "one size fits all" images (like the TMO Bearing Tool) will only work with the particular resolution/aspect ratio it was made from. Using other game resolutions will produce an error in size when the image is not rendered correctly, causing the type of measuring error you see here.

In the "Downloads" menu of this forum you'll find 16 different "3000 Yard Bearing Plotter" mods, each specific for a resolution a player may use as his computer setup is configured. The only way to get the Bearing Plotter to read range correctly was to make a specific Plotter for the different resolutions used, and for the different Imperial or Metric measurement option one may choose. Here's a link to the "1024x Imperial" 3000 yard Bearing Plotter. Choose whatever resolution and unit measurement option that fits your setup.

Let me warn you though, the 3000 Yard Bearing Plotter can be a memory hog at some of the higher resolutions. For the image to be rendered correctly, the Bearing Plotter image I used will be measured in feet, not inches, in over all size! This can make it a possible "drag" on your system. Those having a lot of horsepower under the computer hood may not see a problem, others may. Something I could do is make a smaller version of the Plotter, say at 1500 yard distance. That would cut the size of the image a great deal, allowing for less memory to be used.

In the updated version of OTC for TMO 2.5, I have removed the range rings on the Bearing Tool. Using the games Nav Map ruler tool will give you the correct range, given its limitations of increments reading every 50 yards.