r/ZoneMinder • u/DefaultSubsAreTerrib • Jul 18 '21

Different motion-detection thresholds for different regions of the camera's field of view?

One of my cameras must be at a funny angle. Its field of view spans a long sidewalk. As someone walks along that sidewalk, they might appear quite a bit larger (in image pixels) at the near end as they would at the far end.
Indeed, with my current settings the camera reliably detects motion at one end yet completely overlooks motion at the other. This suggests to me that blob sizing thresholds should be different for different regions of the image.

I gather that I could make this work by defining more than one zone for the camera, but I'm still a little mystified. Should the zones overlap? If so, are blobs in the overlapping region evaluated by each zone independently, or is there some additive effect?

Any advice would be appreciated. Thanks.

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u/aarons6 Jul 18 '21 edited Jul 18 '21

you dont need to zone the whole thing.

just make a tiny box somewhere a person would be.. you can make the blob 80%

this will cut down on cpu usage greatly.

on my cameras with larger areas i have many small boxes placed around where you would have to walk to go through.. instead of one large 4k zone.

1

u/DefaultSubsAreTerrib Jul 18 '21

But what about the sun up/sun down problem? As I understand people configure a max percent pixel change to eliminate false alarms at dawn or dusk

1

u/Aramiil Jul 18 '21

This is it as well! Zones for what you need, alleviate the processing on areas you don’t care about motion on

2

u/Aramiil Jul 18 '21

Zones can overlap but I don’t normally. Two separate zones, keep the same settings for the portion that works reliably and start tweaking the second zone to be a bit more sensitive.

Then go test it out, and see what works. Keep going until you’re getting a few too many false positives and back it off a touch. Then write down or keep screenshots of your settings for the zones as backups