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Old 05-08-20, 09:59 AM   #1
XenonSurf
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Default Visual detection by enemy

Hi,
Currently I'm playing with the stock icons on the map, which means it displays blue, red icons + the visual detection rings for enemy ships.
I will however turn these 'cheats' off shortly.


From the enemy ship's behavior I have noticed that it hardly makes a difference wether you have little aspect angle towards the enemy or not in order to be visually detected. I had little aspect angle at dark night and yet i was detected at a fairly big distance away on the surface. This would make night surface attacks generally very difficult. I have never seen these 'enemy circles' change their size which they should depending on my sub's visibility (or they did and I didn't notice?).


Take these situations:


------->


i
i
i


Where the first line with the arrow is the enemy ship moving with an AOB of 90° to my sub below (vertical line). This should be an ideal aspect angle to avoid detection at least at maximum detection range noted by the enemy 'circle'. Instead you would immediately be detected in such a situation if too close:

------->


___


with the below line being my sub presenting all the aspect angle to the enemy.


I wonder if this is simulated in SH4. Of course to answer this sort of question (and also the sonar question in my other thread) I could simply consult the sim.cfg file, but this would spoil the game for me forever, which I don't want, so I'm never going to look in this file. I only want to know if this is accounted at all in the game, yes or no, and with all important mods like TMO, FORTSU. I guess in RFB, the most realistic mod, this is surely simulated.

Thank you to let me know!



XS

Last edited by XenonSurf; 05-08-20 at 10:42 AM.
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Old 05-08-20, 12:58 PM   #2
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Quote:
Originally Posted by XenonSurf View Post
Hi,
I wonder if this is simulated in SH4. Of course to answer this sort of question (and also the sonar question in my other thread) I could simply consult the sim.cfg file, but this would spoil the game for me forever, which I don't want, so I'm never going to look in this file. I only want to know if this is accounted at all in the game, yes or no, and with all important mods like TMO, FORTSU. I guess in RFB, the most realistic mod, this is surely simulated.

Thank you to let me know!
XS
in my experience, yes, your subs aspect plays a part in being detected.
also, darkness, wave activity (high wind speed), fog, rain, and most importantly, enemy ability.
please keep in mind that there are four levels of competence for each enemy ship...even the merchies, who will fire on you if they "see" you and if you are within range of their limited but lethal weapons.
would write more but i have to get back to work.
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Old 05-08-20, 01:14 PM   #3
XenonSurf
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Quote:
Originally Posted by KaleunMarco View Post
in my experience, yes, your subs aspect plays a part in being detected.
also, darkness, wave activity (high wind speed), fog, rain, and most importantly, enemy ability.
please keep in mind that there are four levels of competence for each enemy ship...even the merchies, who will fire on you if they "see" you and if you are within range of their limited but lethal weapons.
would write more but i have to get back to work.

Thanks very much KaleunMarco, that's very good news for me who sometimes like it to be realistic.


Cheers,
XS
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Old 05-08-20, 05:44 PM   #4
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Previous discussions;

https://www.subsim.com/radioroom/sho...d.php?t=240550

https://www.subsim.com/radioroom/sho...d.php?t=210786

In the stock game, the visual in the sensors/dat file is used by all enemy ships, the listings for generic radar and sonar are not used by any of them. Instead they use different radar and sonar models based on the .sns file for each ship.

In the sensors.dat file the max range is given, and the circle displayed on the map is actually the average range, not the max range. "Average" works out to about 0.58 converting from meters to yards, so if the max range listed in the sensors.dat for any given detection system is 10,000 meters, the ring will have a radius of 5800 yards. That means you can still be detected outside that ring, rule of thumb is a bit less than twice the radius of the ring for safety. They might not detect you inside the ring for a while, depends on the skill level of the crew and how much rum the lookouts drank.

Further complication, in the notes under "Sensitivity" it says "The sensity of the sensor. At (Sensitivity * MaxRange) distance we have a double detection time. If 0, then the value from sim.cfg file is taken."

Look in the \Cfg folder for sim.cfg, plain text file;

[Visual]
Detection time=0.5 ;[s] min detection time.
Sensitivity=0.1 ;(0..1) min detection threshold double detection time.
Fog factor=1.0 ;[>=0]
Light factor=2.5 ;[>=0]
Waves factor=4.0 ;[>=0]
Enemy surface factor=50 ;[m2]
Enemy speed factor=25 ;[kt]
Thermal Layer Signal Attenuation=1.0

The light factor is what changes the sensitivity when it's dark outside, some of the other data is still open to debate - there's no thermal layer factor if you're running on the surface, so why that was included is a mystery.

Experimenting with the light factor I found that increasing the number also affects daytime detection range, dunno why.
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Old 05-08-20, 06:28 PM   #5
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I noticed too when I made a simple mission, as stated above ships have different capabilities, like novice to elite, so you might have met a convoy with some elite DD's as escorts.

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Old 05-09-20, 11:07 AM   #6
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This should answer most of your questions on when the AI will detect you:

https://www.subsim.com/radioroom/sho...52&postcount=1

obviously what mods you have installed will have a big influence on when you will be detected.

The circle you see around ships seems to be the max detection range. You can on occasion go well within that circle without being detected.

Night surface attacks are a weak point in SH4. However, with the stock SIM.cfg file, it should be possible to sneak up to 2,000 yds before the AI detects you at night in good weather. I managed once to get within 1200 yds before I was detected.

Note also that if any ship in a TF detects you with radar, every other ship is automatically alerted. Many late war IJN warships are equipped with some kind of radar.

One tactic you can use, although some consider it to be gamey, is to go "decks awash". You can still man the bridge, but the game considers your sub to be submerged and therefore harder to detect.
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Old 05-09-20, 12:47 PM   #7
XenonSurf
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Thank you folks, I highly appreciate your answers. I forgot about different enemy skills, so I must have been out of luck in my last night attack mission. Also I didn't account for my sub continuing to drift if I stop engines after flank speed, so I probably got much closer than I wanted.



I'm actually surprised by the numerous factors involved in getting you spotted, I find that's rather good!



Greetings,
XS
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Old 05-09-20, 07:31 PM   #8
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"The circle you see around ships seems to be the max detection range."
Somebody didn't read my post. Maximum detection distance is about 175% of the ring radius.
"You can on occasion go well within that circle without being detected."
True, depends on several factors including crew quality and numbers in the sim.cfg file. Dark night heavy weather low visibility rain you can pretty much run head on into an enemy ship and he still doesn't see you. Daytime flat calm an elite crew will start dropping accurate fire on you way outside the ring.

I agree with most of Ducimus's guesses (note the disclaimer at the beginning), but he's wrong about the speed factor;

"- speed factor in this case means that you must be doing 15 kts or more for the AI to notice you."

If that was true the S class would always be completely invisible. I think what it means is when the enemy is going fast he's less likely to see you, same applies to sonar. My testing shows full speed surface running by the sub makes no difference at all in detection range, we can see the bright white spray kicked up by the sub, the enemy AI can't see that at all. Same with muzzle flashes, in real life you fire the deck gun at a destroyer from 4 miles away he wouldn't see the sub in the dark, but he would see the bright light from the muzzle flash and start firing at that. The game doesn't simulate that, until you actually hit him he's blissfully unaware that he's being shot at.

One trick I use often;

https://www.subsim.com/radioroom/sho...d.php?t=211613

Flooded down to 25 feet the diesels still run, so at flank speed you can run at 12 knots or more, get to within 3000 yards in the daytime and 1500 yards at night without being seen since it's a smaller profile. The spray kicked up should be visible to the AI but it's not.

If you don't like the detection programming you can make a backup copy of sim.cfg, then tinker with the values (it's a standard text file), and/or use S3D to play with the numbers in the AI_sensor.dat file. Either way be aware that the whole thing is a variable, and a wise skipper will err on the side of caution.
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Old 05-10-20, 09:48 AM   #9
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Quote:
Originally Posted by Sniper297 View Post
"The circle you see around ships seems to be the max detection range."
Somebody didn't read my post. Maximum detection distance is about 175% of the ring radius.
well actually, it seems to depend on what mods you are using and other factors. I just checked my TMO instal, max range of escorts visual sensors is 12,000 yds, but the circle in daytime tops out at 11 nm, i.e. 22,000 yds, so obviously other factors are in play.


Quote:
"You can on occasion go well within that circle without being detected."
True, depends on several factors including crew quality and numbers in the sim.cfg file. Dark night heavy weather low visibility rain you can pretty much run head on into an enemy ship and he still doesn't see you. Daytime flat calm an elite crew will start dropping accurate fire on you way outside the ring.
It is actually easier to see what is going in under the hood when playing SH5, there you see that the visual detection circle expands and contracts in real time based on various factors, including the "alert" state of the crew. There seems to be at least 3 alert states, i.e. "asleep", AI does not expect you to be around so circle may only cover the ship itself; "alert", AI knows you are around and will start to look, circle gets bigger; "detected", one ship has spotted you, alerts other ships who start to spot you, circle expands to max extent.

Quote:
I agree with most of Ducimus's guesses (note the disclaimer at the beginning), but he's wrong about the speed factor;

"- speed factor in this case means that you must be doing 15 kts or more for the AI to notice you."
Agreed. I think the speed factor refers to something other than straight speed. Note that the sensors cfg file also impacts visual detection.

Quote:
My testing shows full speed surface running by the sub makes no difference at all in detection range,
actually the game does consider those factors and you can see it in SH5. The visual detection circle is at its smallest when your sub is motionless and bow on to the target, but expands as you increase speed and/or turn parallel to the target.
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