Motion - Config Option Threshold

threshold

  • Type: Integer
  • Range / Valid values: 1 - 2147483647
  • Default: 1500
  • Group: Motion Detection

Threshold for declaring motion. The threshold is the number of changed pixels counted after noise filtering, masking, despeckle, and labelling., Threshold for declaring motion. The threshold is the number of changed pixels counted after noise filtering, masking, despeckle, and labelling.

The 'threshold' option is the most important detection setting. When motion runs it compares the current image frame with the previous and counts the number of changed pixels after having processed the image with noise filtering, masking, despeckle and labeling. If more pixels than defined by 'threshold' have changed we assume that we have detected motion. Set the threshold as low as possible so that you get the motion you want detected but large enough so that you do not get detections from noise and plants moving. Note that the larger your frames are, the more pixels you have. So for large picture frame sizes you need a higher threshold.

Use the -s (setup mode) command line option and/or the text_changes config file option to experiment to find the right threshold value. If you do not get small movements detected (see the mouse on the kitchen floor) lower the value. If motion detects too many birds or moving trees, increase the number. Practical values would be from a few hundred to 2000 indoors and 1000-10000 outdoors.
Topic revision: r15 - 07 Aug 2016, KennethLavrsen
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