Dahua NVR21-4KS3 Series User Manual page 277

2) Click
The system triggers an alarm only when the size of detected target is between the
maximum size and the minimum size.
3) Set parameters.
Parameter
Preset
Name
Duration
Sensitivity
4) Click OK.
Step 6 Configure alarm schedule and linkage.
Figure 5-150 Crowd gathering
to draw the minimum size or maximum size to filter the target.
Table 5-38 Crowd gathering parameters
Description
Select a preset you want to use IVS.
Customize the rule name.
Set how long the object stays until the alarm is triggered.
You can set alarm sensitivity. The higher the value, the easier to detect
crowd gathering but meanwhile the higher false alarm rate.
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User's Manual