A cross line detection tool is a VMDA detection tool that triggers when the object trajectory in the camera FOV crosses a virtual line.

To configure a cross line detector, do the following:

1. Go to the VMDA detection object settings panel.
   
2. Select a line type (straight or polyline) the crossing of which leads to a detector triggering. Only one line can be added. The first line will be deleted if there is an attempt to add a second one.  
   
   1. If a detector is to trigger while crossing a straight line, click the Add line button (1).
   2. If a detector is to trigger while crossing a polyline, click the Add polyline button (2).
3. In the Video preview field (4), set the end points of the line, by clicking left mouse button, which crossing leads to a detector triggering.
   

4. Make the necessary operations with a line. The operations are shown in the table.

   Operation	Result
   Left mouse click in the video surveillance window	Creation of a line’s end point
   Hover to an end point and holding the left button pressed move the mouse	Shift of a line’s end point
   Hover to an end point and click the right mouse button	A line’s deletion

   
   

5. To select object type for which the detector will be enabled, click the  symbol. Available object types are:

   1.  Any object. Detector triggers when the line is crossed by any object
   2.  A human. Detector triggers when the line is crossed by an object which width is less than height.

   3.  Vehicle. Detector triggers when the line is crossed by an object which width is greater than height.

      Detection of the following object types can be configured using scripts and registry keys: a human, a group of humans (with a possibility to count the number of people in a group), a vehicle, noise, an object carried into the area, an object carried out of the area, other objects. See also CAM_VMDA_DETECTOR VMDA detection section of the Guide for creating scripts (programming). More precise objects classification can be performed using the neural filter (see Configuring the neural filter).

      
      

6. To set the object color to be triggered by the detector, click the  icon. The color picker palette will open. Circle the required color range with the left mouse button.
   

   To reset the selected color range to the default value, right-click in the palette area.

7. By default, the detection tool triggers on line crossing in both directions. Click the left mouse button upon one of the arrows to ignore crossing in one of the directions. The arrow will be colored gray.

   When just added, the arrow has minimum length.

   
   The approximate speed of detected objects as a percentage of the frame per second is displayed near the arrow. Change the speed by moving the arrow head with pressed left mouse button and changing the arrow length. The detection tool is triggered when an object crosses the line in the selected direction with a speed that is approximately the same as the specified speed. At minimum and maximum value of speed the "?" sign will display and the fact of line crossing will be detected regardless of the speed.
   In order for the detection tool to be triggered when object speed is less than the specified speed, specify the id of the detection tool in the VMDA.useSpeedLimitTypeLessThan parameter (for details on the key, see Registry keys reference guide).
   In order for the detection tool to be triggered when object speed is greater than the specified speed, specify the id of the detection tool in the VMDA.useSpeedLimitTypeMoreThan parameter (for details on the key, see Registry keys reference guide).

   For more information about working with the registry, see Working with Windows OS registry.

   
   

   The same VMDA detector id can only be specified for either the VMDA.useSpeedLimitTypeLessThan or the VMDA.useSpeedLimitTypeMoreThan parameters. The simultaneous operation of both these parameters for the same VMDA detector is not allowed.

   
   

   It is necessary to set at least one object direction across the line.

   
   

   If both directions are set, the detector will trigger at line crossing by an object in any direction.

   
   

8. Set the Generate alarm on camera checkbox (5), if the camera alarm should be generated when the detector triggers.

9. To display the tracks of objects detected by the cross line detection tool regardless of whether the corresponding setting of the Tracker object is enabled, set the Show event on screen checkbox (6).
   
10. If the video in the preview window is too distorted, set the Show actual video aspect ratio checkbox (7). In this case, the video may not occupy the entire area of the preview window.

11. To save the changes, click the Apply button (8).

    To clear the preview field from a visual element (a line), click the Clear button (3).

    
    

A cross line detector is configured.