Do we need/want an AIS filter?

[rgleason]

Rooie Dirk's suggestion to reduce clutter is based upon a point system which reduces the size of the "contact". I think it makes sense because it accommodates level of risk. IMHO "Yes", to his question.

What other declutter methods should be added?

What can be done about Alarm Acknowledgements?

[rgleason]

OpenCPN AIS Options > Ships > AIS has:

Under CPA Calculation
Check - No CPA calculation if target range is greater than (nm) (Like a Radar Guard range and Proximity setting.)

Under Display
Check - Hide Anchored/Moored Targets, speed maz (kn)

Under CPA/TCPA Alerts
Check - Supress alerts for Anchored/Moored Targets
Check - Play sound on CPA/TCPA alerts...
Check - Enable target alert acknowledge timeout (minutes)

====
So there are just a few additional filters which might be effective {noted above]

[rgleason]

Alarm settings ideas
1. Proximity FS #1881 - Establish a guard zone (distance) as in radar. Include a time element guard zone. -DONE
2. Reduce nuisance alerts FS#807 - Add damping factor adjustable seconds of continued alert conditions before the alert sounds -not implemented
3. AIS Alarm acknowledge shortcut FS#1260 Provide a shortcut key + left mouse to close one or all Acknowledge alerts that are outstanding. -Not implemented, but does have Target Alert Acknowledge Timeout (min)
4. Temporarily Disable Alarms FS#1573 - Provide an Icon Button toggle to temporary stop all acknowlege alerts. - not implemented
Provide audible alarm instead (option) -Has audible alrm checkbox
5. Small AIS enhancements FS #668 - See #5

Alarm Clutter ideas
1. Suppress CPA calc for boats at anchor FS #1826 -DONE- Implemented - Under CPA/TCPA Alerts -Checkbox - Supress alerts for Anchored/Moored Targets (reduces load & clutter, but what happens in fog? hit boat at anchor? or depend on radar?)
2. Make Make targets user definable FS #668 - not implemented, but RooieDirk's idea is more logical and ordered in the way it adjusts the size of the AIS.

Permanent Disable for certain types
FS 1884 AIS Remember "white" list - fleet, disable alarm, proximity - Similar to Vesper.
Hakan implemented "Follower" class which disables alarms, Vesper has some additional nuances.

The suggested filter for SOG max - is Implemented - DONE - Under Display, Hide moored/anchored targets, speed max (kn) .2 user defined.

So the 3 red ones should possibly be implemented. Any thoughts?

[Paul Elliott]

Originally Posted by rgleason

Alarm settings ideas
2. Reduce nuisance alerts FS#807 - Add damping factor adjustable seconds of continued alert conditions before the alert sounds

For what it's worth, NavMonPc has a fixed filter that reduces the chance of transient CPA/TCPA alarms. In my first implementation I had no damping and I would generate alarms as vessels were turning and temporarily creating a CPA/TCPA condition. I now have fairly slow filters with hysteresis that have essentially eliminated this problem. They aren't adjustable, but I haven't personally found this to be a requirement. I don't recall the exact timing, but it's probably about five seconds. I don't consider Rate of Turn in my filtering, but that might be a good idea.

Perhaps OpenCPN already has similar filtering. In any case, I don't see a need beyond a fixed filter.

[rgleason]

Thank you Paul, It does not appear OpenCPN has this filtering, but it may be embedded in the code.

NavMonPC is an excellent tool, and it shows in details like this. If Opencpn does not have this filtering, I'd like to vote for one like this.

Could be implemented
FS#807
FS#1260
FS#1573

Could be augmented
FS#1884

I think we should be closing
FS#1881
FS#1826
FS#668 (after RooieDirk makes his proposed filter).

[rooiedirk]

A first rough version to show what I had in mind. Top is as it now, bottom with the top 10 priority normal and the rest small.
Did a lot of thinking about showing AIS targets last 24 hours. What came up myu mind is the GUI. We have now a button to switch off AIS. Could this button be enhanced to a cycle. So 1 click is targets off, next click SOG=0 off (if enabled in options), next click filter and last click on complete.

[Dockhead]

I will speak up here as I have used the OpenCPN AIS function in a few thousand miles transiting the busiest shipping lanes in the world in the English Channel and North Sea.

First of all, I would suggest being very cautious about tinkering with it -- the OpenCPN AIS function is absolutely superb, head and shoulders above what is built into commercial chart plotters. It would be damned hard to improve on it.

Second: Even in the waters where I sail, I have no need for any filter. The display, especially on a big screen, is well enough presented that clutter of AIS targets is not a problem. I would not like for AIS targets to drop off the screen.

In my opinion, what you should concentrate on is differentiating targets in some other way, than by just dropping them off the screen through filtering.

You could present targets in gray or grayed out according to certain settable criteria (Class "B", not under way, nav status at anchor, CPA more than x, TCPA more than y, etc.).

What would be more interesting would be highlighting targets which are of enhanced interest according to certain criteria. For situational awareness, I would be especially interested in targets which are turning, for example. O already shows arrows at the ends of the COG lines of targets showing turning. Maybe we could set parameters to change colors too, for targets turning at greater than a certain rate?

Then obviously collision risk as determined by CPA and TCPA set according to certain criteria would always be helpful -- red target, flashing red, etc.


Then one AIS function which would be terrific would be an easy way to create sets of parameters from which you can easily choose for different situations -- like "Coastal", "Offshore", "Harbour", etc. So that we don't have to go in an reset the whole set of criteria every time.


But in general these are details and I have to say again -- OpenCPN is the killer AIS app as far as I'm concerned. The last two summers when dealing with very, very difficult traffic situations in hairy places like the Elbe approaches or the Dover Straits -- I left a crewman at the helm and managed collision avoidance from the nav table using OpenCPN and radar -- it was absolutely superb. So no improvement is really urgently needed, as far as I'm concerned, and big kudos to the developers

[Dockhead]

Originally Posted by rgleason

. . .
Alarm Clutter ideas
1. Suppress CPA calc for boats at anchor FS #1826 -DONE- Implemented - Under CPA/TCPA Alerts -Checkbox - Supress alerts for Anchored/Moored Targets (reduces load & clutter, but what happens in fog? hit boat at anchor? or depend on radar?). . .

I've never understood this. What difference does it make, that the vessel is moored or anchored, if you've got a collision risk?

The problem of alarm clutter does not come from moored vessels. The alarms will be valid with regard to moored vessels, unless you are turning.

The main problem of alarm clutter is from vessels maneuvering in channels, where they are turning or will turn. Then you will get invalid alarms.

The other main problem with alarm clutter is changing CPA horizon in different situations. One or two miles CPA and 30 minutes TCPA, say, which is totally appropriate in open water, will produce a constant stream of alarms in coastal waters. But the answer to this is not suppressing alarms, but setting up different criteria, for what is an alarmable collision risk, in different situations.

In harbours and approaches, I switch off ALL AIS alarms -- I don't quite imagine how you can have any useful AIS alarm in such a situation. Collision avoidance works in an entirely different way, when maneuvering in harbors and when following channels.

[rooiedirk]

In my opinion, what you should concentrate on is differentiating targets in some other way, than by just dropping them off the screen through filtering.

I fully agree. That why I started this. There is a possibility to hide anchored and moored targets build in now. We probable agree that this is potential dangerous. Thats why I wanted something to show ALL targets. (Maybe using the word filter was a mistake.)
As for the alarms, I don't know realy. I never use them. If you need an alarm to find out there is a collision danger, you are a terrible watchkeeper. Apart of this when there is a collision danger the last you want is clicking away acknowledgement screens to get back to your plotter. (this is my personal opinion)
Changing color of the targets is just good enough and already implemented.
However for those who do use alarms, a small delay in raising an alarm when there is a course change of the target or of your own ship, could be usefull.

[rgleason]

Rooiedirk, Dockhead
I like the idea of a rolling icon for setting AIS. Ocpn_draw had that for awhile and I think Squiddio has it.
I think Dockhead's observation that at coastal level there are lots of alarms and cpa and tcpa have to be reset due to too many alarms is absolutely true.
I also like his idea to have ocean setting, coastal setting with size declutter and closer cpa tcpa, and harbor setting with alarms off would be good.

If there was a shortcut to acknowledge all alerts and one to shut that off it might be good.

Also I think the idea of having an adjustible alarm dampener time period would help, but neither of you picked up on that.

It's nice to have some say how good the AIS is, but I think it can be better. There are lots of AIS requests from users which suggests that it is still a work in progress.

Thankyou for bringing your experiences and skill to the problem!

[rgleason]

PS I would also like a fourth click on the icon to turn off AIS altogether. Or some key shortcut to do that. I suppose you could do that by filtering the nmea stream or hardware turn off... It might be easier form opencpn, but don't want it to be confusing to people.

[Dockhead]

Originally Posted by rooiedirk

. . . As for the alarms, I don't know realy. I never use them. If you need an alarm to find out there is a collision danger, you are a terrible watchkeeper. . . .

It depends on where you are sailing. On long passages in open water, AIS alarms (and radar guard zones) are an EXCEPTIONALLY valuable enhancement to watchkeeping. In waters where you might not see another vessel for hours at a time, no one is going to be staring at the horizon 60 minutes out of every hour.

AIS alarms are also exceptionally valuable to draw your attention, in crowded waters, to one target out of possibly hundreds which suddenly apears on a collision course with you. There is no way that human watchkeepers can track more than a certain number of targets, even with AIS, and be alert to a collision risk, without an alarm.

Effective collision avoidance demands detection of a collision risk in time to take effective action -- 10 miles off is a good rule of thumb in open water. Without an alarm, in crowded waters, you might have to track hundreds of targets and check CPA and TCPA of each, in order to detect a collision risk in time -- not possible in many real life cases without an alarm.

[rgleason]

RooieDirk I think your visual declutter example is good and should be implimented for coastal and harbor settings.

[rooiedirk]

@Dockhead. As said, that's my personal opinion. As merchant captain on many different ships, which are not familiar to me, you don't want to know how much time I spent on trying to track down an alarm that is sounding on the bridge. Is it the VHF, radar, bilge, AIS, echosounder, engineroom, autopilot, GPS, a nav-light broken, watchalarm, Cellphone or Satphone, telex, navtex or is it just the cook on the telephone asking if I want coffee??

[Dockhead]

Originally Posted by rooiedirk

@Dockhead. As said, that's my personal opinion. As merchant captain on many different ships, which are not familiar to me, you don't want to know how much time I spent on trying to track down an alarm that is sounding on the bridge. Is it the VHF, radar, bilge, AIS, echosounder, engineroom, autopilot, GPS, a nav-light broken, watchalarm, Cellphone or Satphone, telex, navtex or is it just the cook on the telephone asking if I want coffee??

LOL -- I can imagine. I sometimes have such situations even on my little 31 95/100 registered tons vessel.

But considering how many of those alarms you mention can be a matter of life and death -- it's worth tracking them down, isn't it? You wouldn't want to do without a bilge alarm, would you? Or depth sounder? Autopilot? Loss of position data?

Managing alarms is a serious subject and the more centralized and better organized, the better.