Motion Detection - Oject size exceeds

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Camera properties -> Motion/Trigger -> Object detection - Edit: Reset detector when: Object size exceeds

Use the Object size exceeds setting to reset the motion detector when very large objects are detected. This will help to prevent false positive triggering in the event of scene or major lighting changes.

Maybe I'm a bit slow on the uptake, but I have only just noticed this setting. I have however noticed that when the cams switch from day to night mode they no longer set of a motion alert, with the exception of the one cam which isn't using object detection.


It looks like 67% is set as the default for any cam with object detection enabled. I'm assuming that the % relates to the entire image, rather than the active mask/s area. If anyone knows for sure please say.


This could be a great feature for eliminating false alarms due to lighting changes etc, but I'll be watching it closely to see how it affects alerts in general. I suspect some cams it will be ideal for, but others, where you want to catch someone walking past very close to the camera for instance, it might cancel wanted alerts.


Of course it won't be of any use to those who choose not to use object detection in order to have maximum motion sensing sensitivity.

 

[pozzello]

this feature (checkbox and % level) was just added to BI in response to reports of
large objects moving thru the frame NOT setting off motion detection.

it was previously hard coded to ignore changes greater than 67%
(2/3 of the pixels in the frame 'changing', i guess). dunno if it considers any configured mask.

I've bumped it up to 85% and I'm still seeing BI not trigger on cars going by (even tho
it seems to catch every bicycle) so I'm not convinced this new frob is addressing the reporting problem,
but it's nice to have things to tweak. I'll be testing with the box unchecked next...

 

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It's certainly drastically changed the behaviour of motion detection for me, even if I change nothing and if it was a default previoulsy. For instance, I can now walk in front of a cam, momentarily obscuring it completely, that I only want to detect motion in a mask at a distance (relatively small object size) and it doesn't trigger. Excellent.

A long time ago now I asked Ken if he'd consider an optional "maximum object size" for this reason, so this fits the bill for that, and helps eliminate some false alarms.

Although your issue with the passing cars sounds a worry. Do they fill the screen suficiently to take up at least 85% of the view if you combine the frames taken to capture them drive by? I wonder over what time, or how many frames, the percantage is determined. I'd sort of assumed it might be "if on any one frame the object fills at least xx% then..." but maybe that's not the case.

 

[105437]

I'm very interested in this setting. I just set it for 85% and now day -> night mode doesn't trigger and alert. Nice!

 

[djmt99]

I actually JUST emailed Ken as to what the percentage refers to. It would make sense if it were the whole frame, but I just want to verify.

Funny part is that I had started my email yesterday, along with a few other questions that I've been adding to it as to not bombard him with multiple emails. At the time, this post hadn't existed.

 

[MikeyOnline]

I was the one (followed by another user) having issues with object detection on a telephoto camera, where larger vehicles swept the whole frame. Found out from Ken that when an object exceeded 67% of the frame, it reset the motion sensing. He made this an option and now when I uncheck that box, I can use object detection and it fixes the full frame sweep issue for me. When Ken emailed me, he used the term "upper limit of 67% of the frame" so I assume he meant that the motion sensing is reset (canceled) when the object exceeds 67% of the entire frame: now adjustable. I'm not 100% sure though that it means 67% of the entire frame... versus just 67% of the height or 67% of the width. I think it refers to the entire frame (X*Y).

Mike

 

[BPet]

Anybody ever hear back definitively from Ken on whether this refers to the 'frame' or the total of the zones? I think that Blue Iris ignores areas that are not in Zones and so if you don't create a large mask zone - then I'm thinking that it is only going to take into an account the pixel change in the total of the smaller zones? Definitive clarification would help with falses

 

[BPet]

I emailed Ken and he confirmed that the Object Size Exceeds percentage refers to the "Total Image Size", not just the active pixels. Hope this helps someone in the future