Motion Detection Questions

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wildneg
Posts: 3
Joined: Wed Jan 11, 2012 2:21 am

Motion Detection Questions

Post by wildneg » Wed Jan 25, 2012 1:03 am

I'm not sure if anyone has even come close to mastering the Zone Settings and Motion Detection or not.

I've spent a little over a week trying different settings and trying to understand. No matter what settings I choose, I'm always getting tons of false alarms (some settings more then others) and then missing simple things like someone actually walking. So it seems to only pickup the not so obvious yet not pick up the obvious.

I have a shot of my Garage from the house (2 car garage, drive way and walk way).

I've been through many of the settings but just as an example of my last attempt....
Units: Percent
Alarm Check Method: Blobs
Min/Max Pixel TH: 11/0
Filter Width/Height: 3/3
Min Max Alarm: 6/4
Min/Max Filtered: 4/0
Min/Max Blob Area: 4/0
Min/Max Blobs: 1/0

I originally started with the Preset "Best High Sensitivity" and like you would expect, it was pretty sensitive. I would get some false alarms, not to many though. The thing it was missing was obvious things such as the garage door opening and some cars pulling into the drive way. It wouldn't even pick me up walking across the driveway to the other side.

I've adjusted the settings down a little to make the area to view/% smaller to trigger an alarm. I do get just about ever vehicle that comes into the drive way, but i'm getting tons of very simple false alarms. Its strange too because they are the gravel drive way spots. And the change is not even noticeable to the naked eye.

It still wont pick anyone up walking though. So something so obvious (someone walking across the screen) doesn't get detected but something so tiny as a small part of my drive way's gravel color changes (barely notice to the naked eye) it detects.

Anyone have any insight on the issue? I just think something is majorly wrong that it detects very tiny subtle things yet misses the big items I want to capture!

Thanks.

bb99
Posts: 943
Joined: Wed Apr 02, 2008 12:04 am

Re: Motion Detection Questions

Post by bb99 » Wed Jan 25, 2012 1:45 am

I have very few false alarms but am not a master by any means. I'm guessing that you didn't get your source::general::Reference Image Blend %ge and source::buffers::Alarm Frame Count set correctly before messing with the zone settings. Wiki covers them both and without them set for the monitors environment zone settings are much more difficult.

edit: Don't forget about "Overload Frame Ignore Count" on the zone settings page.

wildneg
Posts: 3
Joined: Wed Jan 11, 2012 2:21 am

Re: Motion Detection Questions

Post by wildneg » Wed Jan 25, 2012 2:44 am

Based on all the reading, increasing the %ge to higher then the 7 I have in there now, would prevent less 'false alarms' but would do nothing to detect actual big moving objects, again, like a human walking across the screen. Anything I adjust would make it less sensitive but even with this 'false alarm' detects, i'm still not getting the main movements. That is what is baffling me to no end. With such high sensitivity and all these false alarms, wouldn't you think I would get the very obvious?

I went in and adjusted the %ge a little higher and adjusted the alarm frame count to 2. I had these types of settings before but it didn't do any good. It did lower my false alarms, but it would pick up nothing major what so ever. Even at night, a car drives in the drive way with the lights on, that is a huge amount of change and it wont even detect that.

I almost think I have to make it MORE sensitive, less %ge so the change is greater/quicker, and alarm count back to 1 to get the big obvious movements I want. Only problem, instead of getting over 100 alarms in 12 hours, I'll probably have 200 and MAYBE catch the obvious.

I'm probably just missing some obvious settings :/

Most I read online about setting up, always suggest the High Sens / Fast at default settings. But nothing seems to work well for me.

I'll try adjusting the %ge a little and the alarm frame count to 2. Going through some data today, even the false alarms had 2 or 3 frames in a row of a very slight color change in the rocks due to shadow from a tree or something. So maybe the %ge will help this a little.

Thanks for the info though. I'll let all know if it makes any difference (more/less alarms and if it catches the obvious).

bb99
Posts: 943
Joined: Wed Apr 02, 2008 12:04 am

Re: Motion Detection Questions

Post by bb99 » Wed Jan 25, 2012 3:37 am

Alarm Frame Count and Overload Frame Ignore Count are your friends in a sensitive environment. Reference Image Blend %ge eliminates subtle shadow triggers which are difficult otherwise. I have a monitor watching an outdoor path to the house which gave me the fits (sun, shadows, trees, birds, dogs, distant flashes, you name it) until mastering these three settings. Then defualt zone settings worked fine. Doesn't miss anything now with dang few false alarms. I should mention: 6mm lens on 1/4" CCD sensor analog camera; effective detection, maybe 30-60'. Don't ask the imposible of your equipment, it won't work. Goodluck!

bb99
Posts: 943
Joined: Wed Apr 02, 2008 12:04 am

Re: Motion Detection Questions

Post by bb99 » Wed Jan 25, 2012 4:01 am

Sorry I didn't address your whole post. Large objects will alarm many frames (depending on fps and distance) so increasing alarm frame count would be useful here. Shadows, no better tool then increasing Reference Image Blend %ge. Sudden changes to the enviroment, no better tool then Overload Frame Ignore Count. Your fps determines these settings but at 10 fps with Overload Frame Ignore Count set to 4 only ignors .4 seconds. The only other suggestion I can make is to change blobs to pixels, then you're on your own plus you lose alarm frame highlighting in stills for debuging.

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