Basic motion question: trees suck

[porkchop]

In front of my place there's a tree. It casts a large shadow on the ground, and when there's wind... there's a lot of movement.

frontcamera.jpeg (51.86 KiB) Viewed 2953 times

I understand that motion detection is really just counting pixel change. So I could solve this issue with a chainsaw or moving to a new place. Changing the zone areas isn't really a good option, because the shadows cover the "interesting" area (not to mention the shadows move with the sun).

Is there any other magic I should be aware of? Will setting a Max Threshold work if I just accept that my camera will be blind on clear sunny days?

[knight-of-ni]

Is there any other magic I should be aware of?

You could split the view up into multiple views. Areas showing concrete could have normal Active zones while all other areas have Inclusive zones. This of course is dependant on what you want are interested in recording, which you have not told us. It also will be far from perfect but possibly better than what you have.

I don't think a preclusive zone will help you because ZoneMinder would ignore all events altogether when the shadows are moving.

Will setting a Max Threshold work if I just accept that my camera will be blind on clear sunny days?

You are the only one who can answer that. What is ZoneMinder telling you regarding how many pixels "moved" when it counted the tree or shadow as an event? You could put a number smaller than that value into the max threshold, as long as that number is not smaller than events you consider normal activity and want to record.

If I were you, I would not spend a lot of time on this. Mess with it a little bit, but generally it is better to record more events than too few. To more quickly find relevant events among the moving shadows, use the timeline.

[mikb]

... Or learn how to trigger ZoneMinder using an external trigger wired to a PIR/Radar/Laser beam etc. so it only records when something happens around the car (without using the camera output for motion detection!).

The only way you'd get out of this is for the motion detection to be smarter. All the "motion" of the tree doesn't, on average, *get* anywhere. It just moves on the spot, drifting slowly through the day due to sun angle.

Now, if you could identify that the tree.shadow was "changing, but not moving" you could separate that from "changing and moving" -- the apparent centre of the blob of motion would move for a person approaching the car, car driving off etc. This is the important stuff.

I've had ZM get all over-recordy when someone dumped a car with the hazard lights left on -- then constant changing illumination triggered it for hours overnight. Until the car battery died.

This is (I think) beyond ZM's current motion detection algorithms, but I'm sure there's stuff out there to do this. OpenCV may have some examples of blob tracking within a video stream.