Vivotek PZ7121 User Manual download pdf (Page 53)

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User's Manual - 53

A green bar indicates that even though motions are detected, the event will not be triggered because the

image variations are still falling under the dened threshold.

NOTE

► How does motion detection work?

There are two parameters for setting the motion detection: Sensitivity and Percentage� In the

illustration above, frame A and frame B are two sequential images� Pixel differences between the

two frames are detected and highlighted in gray (frame C), and will be compared with the sensitivity

setting� Sensitivity is a value that expresses the sensitivity to moving objects� Higher sensitivity

settings are expected to sense a slight movement while smaller sensitivity settings tend to neglect

it. When the sensitivity is set to 70%, the Network Camera denes the pixels in the purple areas as

“alerted pixels” (frame D)�

Percentage is a value that expresses the proportion of “alerted pixels” to all pixels in the motion

detection window. In this case, 50% of pixels are identied as “alerted pixels”. When the percentage is

set to 30%, the motions are judged to exceed the dened threshold; therefore, the motion window will

be outlined in red�

For applications that require higher security management, it is suggested to set higher sensitivity

settings and smaller percentage values�

B D

Percentage = 30%

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Vivotek PZ7121 User Manual Page 53