Configuring perspective

Perspective in the Tracker object is configured in order to set maximum and minimum object size (in meters) for these sizes to be considered correctly regardless of the fact that small objects can look bigger than big objects in the background. Perspective calibration allow better performance of the Tracker object.

If the perspective setting is active in the Tracker object then sizes specified in the Detection parameters tab are not taken into account. The Width, m and Height, m parameters are used instead.

To set perspective there are to be at least three objects of the same size in the scene that is in the camera’s field of view. The perspective will be calibrated by these cameras. Poles, people, etc. can be calibration objects. Calibration objects are not to be on the same line. For higher accuracy they are to be positioned in all frame grounds: foreground, medium shot and background. Though, in some cases this is not obligatory: for instance, if there is no need to detect objects in the background and objects in the foreground are to be detected, then calibration objects are to be positioned in the foreground. The more there are calibration objects, the higher the accuracy of parameters restoration is.

It is also possible to set points on the underlying level and their coordinates in meters (at least 3). This setting is not obligatory. Points setting allow getting track position in absolute coordinates. Points are to be located on one level. Points are not to be on the same line. The more uniformly the points are, the higher the accuracy is.

Note.

Up to 10 calibration objects and background points are allowable. This number can be changed using the PerspMaxObjects registry key (see Registry keys reference guide).

If the perspective is to be considered when setting maximum and minimum object size do the following:

Go to the Perspective tab (1).
Set the With perspective settings checkbox checked (2).
Click the Stop button to stop playback in the viewing tile (3).
Specify the size of calibration object (in meters) in the Object size, m field (4).
Set the position of calibration objects on the video image in the viewing tile as follows:
Note.
Zoom in on the video preview field for more precise positioning of calibration objects. To do that, right-click the video preview while holding the Shift key on the keyboard. The video opens in a separate window, which can be resized by dragging its borders. Close this window after adding all required objects.

Click the Add object button (5).
Position the object over the calibration object on the video image (6).
Correct the object size by dragging its edges using left mouse button.
Note.
To delete an object click the button next to it.
Repeat steps a-c for all calibration objects in the scene.

In the Width, m group set the maximum and minimum width of detected object (in meters) in the From (7) and To (8) fields (8).
In the Height, m group set the maximum and minimum height of detected object (in meters) in the From (9) and To (10) fields.
If required set points on the background as follows:
Note.
Zoom in on the video preview field for more precise positioning of points. To do that, right-click the video preview while holding the Shift key on the keyboard. The video opens in a separate window, which can be resized by dragging its borders. Close this window after adding all points.
1. Click the New point button (11).
2. Position a point on the video image (12).
3. Click the button. The Position, m dialog box appears.
4. Set the point position in meters and click OK (12).
  Note.
  To delete a point click the button next to it.
5. Repeat steps a-d for all required points.
To save the changes, click the Apply button.

The perspective in the Tracker object is now configured.

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Documentation for Intellect 4.10.4. Documentation for other versions of Intellect is available too.