Knowledge Base

View the Detection Features on the Video Window

Important: Displaying detection features can use a lot of processor power and reduce the maximum possible sample rate if you are tracking live.

Procedure

1. In the Detection Settings screen, click the Show/Hide button on the toolbar and select Track Features.
2. Select View for the feature you want to view. Choose the color and, for the body points, whether to show the trails.
3. If you have selected to view the body points' trail, choose the number of Samples you want to be shown at a time.
4. Adjust the Line thickness and the Dot size.
5. Click Close and check the result in the Video window.

Detection Features

Nose-point: To check that the nose tip is detected correctly.

Center-point: To check that the center-point of the subject is detected correctly. The center-point is the point whose X,Y coordinates are the arithmetic mean of the X,Y coordinates of all pixels detected as subject. For more information on how the nose- and tail-base points are calculated, see Overview of Nose-Tail Base Detection.

Tail-base: To check that the base of the tail is detected correctly.

Head direction: To estimate at what the subject is sniffing. Select this option especially with Novel Object and Orientation tests.

Body contour: To check that the subject's contour (or the part which should be found) is detected.

Body fill: To check that the subject's body (or part of it) is detected. For example, in a test where it is important to measure the change in the animal's shape to estimate its mobility. If you do not select a color for Body fill, the body contour will be shown as noise.

Noise: To view the pixels that match the criteria for subject detection (depending on the detection method), but other than those detected as subject. We recommend to keep Noise selected. This way you can see which parts of the video image have gray scale values similar to those of the subject(s) to be detected.

Activity: To view the pixels that match the criteria for activity detection (see Activity Settings). This setting is only available if you selected Activity Analysis in the Experiment Settings.

Some of the options above are not available if your experiment is set to Only Center-Point Detection in the Experiment Settings.

Line thickness: This refers to the thickness of the trails, the body contour and the head direction line.

Dot size: This refers to the size of the body points visualized.

View the Detection Statistics

The detection statistics are displayed in the Detection Performance pane, which is, by default, displayed at the bottom of the screen.

If the Detection Performance pane is not displayed, click the Show/Hide button on the toolbar and select Detection Performance.

The Detection Performance pane shows immediate feedback when you change detection settings.

Missed Samples

The percentage and number of samples that were skipped due to lack of processor time. This value tells you whether your PC can handle the sample rate specified (see Sample Rate). See also Missed Samples for tips on how to increase the maximum sample rate handled by the PC.

The value is reset to zero when you load another video file or click Save Changes in the Detection Settings pane.

Interpolated Samples

The percentage and number of missing samples due to missing video frames that were interpolated. This statistic is only available when in the Detection Settings under Smoothing the option Dropped Frames Correction is On. See Dropped Frames Correction.

• What is the maximum acceptable percentage of interpolated samples? Only accept a high value of interpolated samples when you are sure that the tracks represent the movement of the subject reliably. If the percentage is as high as 30% and the subject moves fast or makes sharp turns, the resulting track includes lots of artifacts and the statistics are unreliable. In Integrated Visualization check whether the tracks with high percentages of interpolated samples match the actual movement of the subject.
• The value is reset to zero when you load another video file or click Save Changes in the Detection Settings pane.

Source: EthoVision XT 19 Help - Configure Detection Settings, Noldus Information Technology