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Hiker
Posts: 11

Motion detection sensitivity?

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Is there any documentation available outlining what the 1-9 actually means in terms of sensitivity? I'll of course do ample testing, but a better understanding of what's going on just beneath the surface would probably help me understand what the best settings would be in my use cases?

I've dug around the GitHub but haven't really been able to find anything.

 

Is the sensitivity based on pixel size, velocity across the screen, or some secret sauce? Based on the B&W trigger images that are saved I'm guessing it's based off of luma values only?

 

For real world applications I'm working with Arctic Foxes and eagles flying far away from camera, up in the sky, where no PIR sensor can see them. I rather have a couple of false positives than a bunch of false negatives, unless the memory card is filling up in no time.

I've been using my cats and park birds for testing, but am thinking perhaps I'm better off setting up a gopro in front of a computer monitor and use something like after effects to animate different shapes to speed up my understanding of what's going on? Any recommendations would be much appreciated!

 

Thank you!

 

GoPro
Posts: 865

Re: Motion detection sensitivity?

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Yes, it is a luma only.  The system is a gridded contrast change detector.  The image is divided into approximately 64x32 blocks, and a mean square error (MSE) is computed for each block as a delta to the previous frame. There is some logic to reduce the impact of sensor noise. The sensitivity setting is used to scale the MSE   block[i] = blockMSE>>(9-motion_sensitivity);  So it is hard to say in absolute terms what each sensitivity means, other than there is a power 2 between each level.  This is a crude motion detection model, so trial and error is best.

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Hiker
Posts: 11

Re: Motion detection sensitivity?

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Thanks a lot Dan! I can't thank you enough for all the new possibilities that the labs firmware opens up and your amazing responsiveness and helpfulness on the forums! Off to trialing and a lot of erroring. :)