CCTV SURVEILLANCE 101: Risks of recording on motion detection
Whaaaat? Yo want to tell me that there are risks? Well consider the following:
The most common way that video management systems are set to record is when motion or pixel changes occur in front of a camera.
- Someone may enter and leave a room before the video motion detection kicks in to start recording, so no evidence is collected.
- There may be big chunks of time missing in the database without recordings that cannot be explained this is due to no-motion occurring in that time period, it could also mean that footage is missing or been deleted or cameras are not functioning.
- Someone may walk to the middle of the camera view then all of a sudden disappear, because the motion detection no longer picks up a pixel change until he is close to the camera, typical for long passages or perimeters.
Suggestions on how to get round this:
To ensure continuity in the database and prove that a camera is always online, the following setting can be made:
- The current camera should be configured to constant recording at a very low frame rate (e.g, 1 frame of video every 1 to 3 seconds).
- When motion is detected, increase frame rate to the desired level, eg, 8 to 12 fps (frames per second).
- 1 to 3 seconds pre- and post-buffering of the recordings will mean the system will write up to 3 seconds of extra footage pre- and post-motion detection.
With this there will be no discrepancies on cameras going offline or the database being deleted or not recording.
However, the above method might have an impact on the amount of data stored.
Video motion detection considerations
The sensitivity level of video motion detection and the amount of pixels that should be detected need to be considered as well. These factors are also influenced by light, image quality and the light sensitivity of the camera.
Mask out areas for detection with irrelevant or interfering motion, such as traffic outside a window. Masking from the camera side will limit the amount of pixels the system needs to process, but may also block necessary information.