I recently turn my Raspberry 3 into a surveillance camera with the official camera. Whenever a motion is detected I receive an email with the video. It works pretty well but I realized that I received mails without any motion. After a closer look it seems that the light triggers the event.

It's the only thing that changes according to me ...

So I've got two questions. Does it possible ? And if yes, is there a parameter to handle this ?

I don't attach my conf file because I don't know if it's useful but I will if it's needed :)

Some help would be appreciated,

Thank you !

  • I'd guess it detects motion by comparing the current frame with a reference frame on a pixel by pixel basis. So I think light would make a difference. Does your motion software have no documentation? Perhaps use different software. – joan Mar 11 '18 at 13:52
  • Thanks for your answer. I’m gonna see on documentation, I hoped someone already had this issue – Hurobaki Mar 11 '18 at 18:16

So I found the solution. The problem was the threshold value by default at 1500. I increased it and it solved the problem.

My configuration is the following, I'm using a RPI 3 model B. I chose to use the software Motion to perform the detection due to many tutorials and documentation. For the camera, I'm using the official RaspiCam.

The threshold option is the number of changed pixels in an image in comparison of the previous one. Because of the light, pixels changed and it causes the event to be triggered. By increasing this value, it avoids detection of the light augmentation.

By default, this value is set to 1500, I turned it to 3000. It needs to perform tests to be sure that the camera still detects real motion. For example, with the new value the event is still triggered by sunrise. But it solves the problem, I have to make adjustments to find the good value.

Here's the official documention of Motion : http://www.lavrsen.dk/foswiki/bin/view/Motion/ConfigFileOptions

If this answer could help someone with the same issue ...

  • +1 I think it's great that you found the solution and posted the answer here as well. There's nothing wrong with accepting your own answer as well, since this can help other people in the future find your answer. However, it would be even better if you added a few more bits of information to your question or answer. How does you system detect motion? Are you using OpenCV? Is there a link to the script you are using? It's hard (for me at least) to know what the threshold means without some kind of reference to where it's used. Thanks! – uhoh Mar 13 '18 at 10:06
  • 1
    Thank you for your feedback Im gonna edit my answer to be clearer ! – Hurobaki Mar 13 '18 at 10:32

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