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[FIXED] Possible BUG - Radar and land mass clutter, terrain masking

 
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[FIXED] Possible BUG - Radar and land mass clutter, ter... - 8/30/2017 11:47:29 PM   
giantsquid

 

Posts: 211
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From: Milan, Italy
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I played First contact scenarios in editor mode and I noticed the attacking formation, composed of Russian ships and helicopters had no problem at detecting the Norwegian ships even when they are very close to the coast.
According to Harpoon4 board game rules, for example, you should have a 50% radar range reduction when ships are very close to the coast, and it makes sense. Some ships can be placed very close to the coast in specific locations with camouflaged nets and be probably undetectable with radars.

I was wondering which kind of radar land mass clutter degradation are modeled in CMANO simulation. I run a test and it looks the detection range of a surface radar vs ship in open water and one within half a mile from the coast look same.

Thanks for the excellent work so far, as always.

Francesco


< Message edited by Dimitris -- 9/2/2017 9:45:59 PM >
Post #: 1
RE: Radar and land mass clutter - 8/31/2017 1:41:14 PM   
thewood1

 

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Joined: 11/27/2005
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Quick search of the forum on the word "clutter" or "masking". Some have a direct bearing on your question, some are more indirect. Note the dates as many changes have happened to the radar models.

http://www.matrixgames.com/forums/tm.asp?m=4135097&mpage=1&key=clutter�

http://www.matrixgames.com/forums/tm.asp?m=3947287&mpage=1&key=clutter�

http://www.matrixgames.com/forums/tm.asp?m=3717219&mpage=1&key=clutter�

http://www.matrixgames.com/forums/tm.asp?m=3406111&mpage=1&key=clutter�

http://www.matrixgames.com/forums/tm.asp?m=3929396&mpage=1&key=masking�

http://www.matrixgames.com/forums/tm.asp?m=3436001&mpage=1&key=masking�


I think there was also a mention in FAQ about terrain masking

(in reply to giantsquid)
Post #: 2
RE: Radar and land mass clutter - 8/31/2017 1:49:59 PM   
thewood1

 

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Joined: 11/27/2005
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btw, if you really want some help, post a save. There are 4 different versions of First Contact and its impossible to see if there is any issue if you don't post a save.

(in reply to thewood1)
Post #: 3
RE: Radar and land mass clutter - 8/31/2017 3:10:15 PM   
thewood1

 

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Joined: 11/27/2005
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OK, I built a test scenario because this area seems to have mutliple posts over the years for issues lilke this one.

I have the red side with one Osa II missile boat and blue side with three of the same. I place one blue boat in relatively open water, one behind a 600ft hill in a fjord, and one snuggled up in an inlet close to the shore facing out to the North Sea. They are pretty close together (within 5nm). I have the red boat coming in from the sea radiating its radar. It detects all three at the exact same distance with no variation...11.7nm.

This is a fairly old radar set that I expect would have difficulty picking up the Osa in the inlet against the terrain around the inlet. I would expect it would be near impossible to pick up the Osa behind the hill. But it picks up all three at exactly the same distance. I am no expert in radar or terrain masking of radar, but this seems odd.

Play as red, just hit start and watch the blue units pop up and note the distance.

btw, ver 1.12.6

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< Message edited by thewood1 -- 8/31/2017 3:28:16 PM >

(in reply to thewood1)
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RE: Radar and land mass clutter - 9/1/2017 11:29:07 AM   
giantsquid

 

Posts: 211
Joined: 9/8/2014
From: Milan, Italy
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Hello thewood, thanks for your help.

I run your test, changing ship position too, but the result is always the same... The radar model doesn't consider the landmass and detects target in the fjord behind mountains 300 ft high. It should detect the ship in the inlet at half the distance (my guess from Harpoon boardgame) or less and NOT detect the one behind the mountain.
This last is odd, because in CMANO terrain masking works for planes and cruise missiles. I mean, you can use terrain to hide your approach from radars.

Given the amazing work done by devs with CMANO details should not be too complex to fix it. It can really ruin most littoral warfare scenarios.


(in reply to thewood1)
Post #: 5
RE: Radar and land mass clutter - 9/1/2017 11:40:00 AM   
thewood1

 

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Joined: 11/27/2005
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A) Don't use a 20 year old board game as the reference for how radar should work. For Harpoon boardgames, it was a guess and they basically had to abstract it. Do you really think its an even 50% for all ships?

B) Never tell anyone developing an application, especially one as complex as Command, that a fix is easy. You don't know how the radar function works at all. Even in real life detecting objects against clutter is completely different for ships and planes.

C) We really don't know how its supposed to work. You can try this scenario in other areas and see if it effects ALL areas or just the fjords. Maybe its just these close-in land masses.

IOW, what is showing has been pointed out before. Declaring it broken and easy to fix without you yourself providing any real help, like what actual scenario you are using or a save file, will not win you much credit.

(in reply to giantsquid)
Post #: 6
RE: Radar and land mass clutter - 9/1/2017 8:47:29 PM   
apache85

 

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From: Melbourne, Australia
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If I'm following correctly, this thread goes like so:

giantsquid: I have a problem
thewood1: here's a bunch of links, newest of which is a year old, most are > 3 years old and not all relate directly to your question
thewood1: provide a save
thewood1: actually I reproduced your problem, the behavior is indeed unusual
giantsquid: thank you for your help, it does appear to be a legitimate bug, hopefully the devs can fix it
thewood1: 3 point scolding

Internet forums, this one in particular, don't need to be places of drama. Treat people with respect.

(in reply to thewood1)
Post #: 7
RE: Radar and land mass clutter - 9/1/2017 10:03:50 PM   
thewood1

 

Posts: 4081
Joined: 11/27/2005
Status: online
Thanks for your help on this issue.

(in reply to apache85)
Post #: 8
RE: Radar and land mass clutter - 9/2/2017 12:11:49 AM   
thewood1

 

Posts: 4081
Joined: 11/27/2005
Status: online
So I decided to test this on some Pacific islands. Same set up, except I am using a red unit with longer-ranged radar. The red unit seems to detect all units in open, in front of terrain, and hidden by the island...at 17 nm regardless of position.

I have included two files; the Pacific file is set up before I hit start and the Pacific 2 file is after it ran and initially detected the Osa behind the island at 17 nm. On the surface, it appears that terrain masking isn't working at all, but it is 99% of the time. The issue is at the radar detection range, any unit is immediately detected, whether in open ocean, in front of terrain, or behind terrain. But if you really watch what happens, after that initial detection, it loses the terrain masked unit, never to reacquire it. You can tell by looking at the timer on the detected unit. It times up to 3-4 hrs and then contact is lost. Unless you turn the red unit around and head back away. As soon as it hits that 17 mi initial detection range, it gets that one detection and then the detection times starts as the red unit speeds away.

So something happens at the initial detection range that causes an initial detection, no matter what. But then the game goes on and seems to use terrain masking properly. This is on units behind terrain. I am trying to get at the terrain clutter issue, and it might be the same thing.

My uneducated guess.

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(in reply to thewood1)
Post #: 9
RE: Radar and land mass clutter - 9/2/2017 2:47:29 PM   
mikmykWS

 

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Added everything relevant to bug fixing to list.

M

_____________________________


(in reply to thewood1)
Post #: 10
RE: Radar and land mass clutter - 9/2/2017 3:28:30 PM   
Dimitris


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Thanks everyone, looking at this ATM to determine if there is any bug/issue. The design of the radar model most certainly includes clutter from nearby landmass as a factor.

_____________________________


(in reply to mikmykWS)
Post #: 11
RE: Radar and land mass clutter - 9/2/2017 9:45:17 PM   
Dimitris


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There was indeed an issue with surface-based radars (airborne systems worked correctly). Fixed for the next update release.

_____________________________


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Post #: 12
RE: Radar and land mass clutter - 9/4/2017 10:41:40 PM   
giantsquid

 

Posts: 211
Joined: 9/8/2014
From: Milan, Italy
Status: offline
I have been away for some day. Thanks to thewood for the nice and clear examples and to the devs for the prompt answer.

Here is another example involving an airborne radar: a helicopter closing to the coast trying to detect enemy patrol boats (switch to India, it’s part of a biggest scenario I’m building). It looks the airborne surface radar is behaving in the same way as shipborne radar, detecting the small enemy ships behind a 500 ft hill, even at moderate altitude.
After initial detection, as thewood mentioned, after some second the airborne radar looses contact and behave as normal, acquiring the ships again only if the helicopter establish a “real” line of sight to the targets.

About the ground clutter: in the simulation I didn’t manage to discover any range/detection degradation by surface radar against ships very close to the coast: I guess more modern radars being less affected by ground clutter than older model. I don’t know about airborne and shipborne radar limitations. The generic 50% range reduction for ships within 1 nm from the coast cited in my previous post is just an abstraction, because Harpoon boardgame has no “radar generations”.

Hope this helps. Save uploaded
Thanks again for the amazing work done so far

Francesco


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< Message edited by giantsquid -- 9/4/2017 10:42:05 PM >

(in reply to Dimitris)
Post #: 13
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