Negative sensitivity area in motion detection to suppress recording




  • Official comment
    Norman Graafsma

    Hi Harald, 

    Great suggestion to improve our VMS. 
    I submitted your ticket to our support portal to share your suggestion with our dev team. 

  • Avatar
    Tuli Dem



    You can acheive that just by selection that area in the motion menu and setting it to 0.

  • Avatar
    Harald Klein

    no, that wouldn't achieve the same. I can't set a sensitivity of 0 to the whole image, because then no motion would be detected. But if pixels change in that specific "negative" area, it is for sure the ceiling light switching on or off, and not somebody walking in front of the camera. 

    From the Zoneminder Wiki:

    But hey what's that preclusive zone in your image at the start of this article?

    ZM allows us to specify a zone where should an alarm occur, it suppresses alarms in that zone and all other zones in the monitor. I've set it to cover my recess lights. So if someone turns our lights on, I won't get an alarm.

    That worked a treat with ZM for my use case. Now I'm searching for the same feature in NX Witness. A negative sensitivity would allow to define such preclusive areas. Movement there would suppress movement detection in the other areas.



  • Avatar
    Tuli Dem

    You didn't "read" what I wrote... I said that you could set 0 sensitivity to a "specific" area. That should achieve what you are requesting.

  • Avatar
    Harald Klein

    I did read what you wrote. But I'm unsure if you do understand the objective. The ceiling light, when being turned on, will change *all* pixels in the image. So just having a specific area set to 0 sensitivity, will not prevent motion detection to trigger. You can try that on your own system. Enable motion detection for a specific area, and then turn the light on at night. It will trigger. Having a specific area high up on the wall - where usual motion does not occur -  set as "preclusive" area, e.g. by sensitivity -1, would prevent motion detection in other areas set with different sensitivity. Did that explanation clarify things?

  • Avatar
    Glen Harrison

    Hi Harald

    yes I agree , mobtotix cameras have this option , to qualify a small region somewhere where motion is not expected.

    Great for controlling motion when sun goes behind clouds and rain etc . 

  • Avatar
    Sergey Bystrov


    Here is another idea. 
    So there are false positive based on lights on/off or camera goes to day/night.

    Based on our observation, such events trigger luminance(brightness) change across all image. 
    So would it be better if we ignore MD if luminance changed across all image?

Please sign in to leave a comment.