Knowledge Base

7 Video-tracking

7 Video-tracking

Important Things To Know

Prepare the experiment

Before you acquire data, make sure that the EthoVision experiment you use for video tracking is optimized for Track3D: The measurement unit is mm (see page 48). The arena is set to pixel calibration (page 49). Trial Control does not have the start track condition (page 50).

Trials vs. tracks

In EthoVision XT, each data acquisition session is called a Trial. You start a trial when you click the Start trial button. The set of 2D x,y coordinates of the animal's center point in each arena during one trial is called a track.

How many trials per subject?

It depends on how many Arena Settings you defined. Here we assume that one subject is tracked at a time. If you defined two Arena Settings, one for each camera view (where each Arena settings containing one arena; recommended), then you acquire two trials per subject. - One trial for camera 1, using the Arena Settings for camera 1. - One trial for camera 2, using the Arena Settings for camera 2. Each trial contains one track for that camera view. In most cases you also use different detection settings for different camera views. 7 Video-tracking If you defined one Arena Settings profile with two arenas, then you

acquire data from both camera views simultaneously, in one trial

per subject. The trial contains two tracks, one for Arena 1 (camera 1)

and one for Arena 2 (camera 2). Figure 16 Typical scenario when using two arena settings profiles. Figure 17 Example of using one arena settings profile. 7 Video-tracking

Tracking multiple subjects in the same chamber

If you have two subjects in the same chamber (for example, bat and moth), then you have two tracks per trial.

Video-tracking Procedure

1. Choose Acquisition > Open Acquisition.
2. Make sure that the correct Arena Settings, Trial Control Settings and

Detection Settings are selected in the Acquisition Settings window

(for example, Arena Settings Camera 1 if you are about to track from

the video of camera 1). To activate a settings profile, right-click it in the Experiment Explorer and select Set as Current. 3. If necessary, add a trial. 4. In the Acquisition Settings window, click

the button next to Video to select the

video file you want to use (if that video file not yet shown in the Video window). 5. Position the video to the time or frame where you want to start. You

can do this by using the Step forward/backward

buttons to play the video frame-by-frame. Take note of the time/frame number when the subject becomes visible in both videos, and use this as starting point. After tracking from the video of camera 1, when you open the video for camera 2, make sure that you position that video exactly on the same time or frame number, otherwise the two tracks will be out of sync when you combine them. - You can check the time/frame number in the lower right corner of the Video window. - To show frame numbers, right-click the Video window and select Position in frames. 6. Make sure that the option DDS is selected in the Playback Control window. 7 Video-tracking 7. Click the Start trial button or press Ctrl+F5 to start acquisition. 8. To stop acquisition, click the Stop trial button or press Ctrl+F6. The trial stops automatically at the end of the video file. 9. Repeat the procedure from step 2 for the video of the other camera.

Notes

After you have acquired data, the Arena Settings, the Trial Control

Settings and the Detection Settings used for that trial become

read-only to prevent accidental changes to the settings that would invalidate your data. If you want to edit the settings, make a copy of them. Right-click the settings profile in the Experiment Explorer,

select Duplicate, and rename the new settings profile. Next, make

the necessary changes to the settings.

To visualize the tracks in 2D, from the Analysis menu select Results,

Plot integrated data. To delete a track, delete its trial. In the Experiment Explorer, under Acquisition, Acquired Trials right-click that trial and select Delete.

Visualize The 2d Tracks

To visualize the 2D tracks, choose Analyze > Results > Plot Tracks. For more information on how to analyze tracks in 2D, see the EthoVision XT Help.

---

Source: Track3D 2 - Reference Manual (March 2025)