Knowledge Base

5 Recording Video

5 Recording Video

Video Quality Is Important

Track3D works at its best with high quality digital media files. The video tracking software EthoVision XT must be able to distinguish the image of the animal from the background to calculate its position and measure its behavior. Several factors influence the ability of EthoVision to find and track a moving object, among which the lighting conditions are the most important. In order to optimize detection of the animal, before you carry out your experiments it is wise to record a few trial videos where the animal moves in different parts of the test chamber, and use those videos in EthoVision to see where and when detection is not optimal. Next, adjust lighting and background characteristics to improve detection. Always use the same software to record video for calibration and for video-tracking.

Record Video With Ethovision Xt

With EthoVision XT you can record video from the two cameras to a single video file of resolution 1280 x 480. (640x480 per camera image).

Preparing the experiment for video recording

1. Start EthoVision XT and open your experiment. We advise you to create an EthoVision XT experiment for recording video only. Name this experiment for example Video recording. In this experiment you do not need to adjust settings like Arena Settings, Detection Settings etc., since you use this experiment only for video recording. For video tracking, create a separate experiment (for details see page 48).
2. Make sure that in the Experiment Settings, Video source is set to Live tracking with Number of sources = 2. 5 Recording Video
3. Choose Setup > Arena Settings > New.
4. Right-click the Arena Settings window, just below the Validate Setup button, and select Set pixel calibration on.
5. Click OK. You are ready to record video.

Recording video

1. Choose Acquisition > Open Acquisition.
2. In the Acquisition Settings window, select Save video only, track later. Click OK on the message that appears.
3. Click the Start trial button (Ctrl+F5).

Result

The video is saved in the Media Files folder of the Video recording

experiment. The default file name is Trial 1, Trial 2, etc. Always keep a copy of your videos in a safe place. 5 Recording Video

Record Video With Mediarecorder

With MediaRecorder you can record video from the two cameras to separate video files of resolution 1280 x 960.

Recording video

1. Make sure that the cameras are powered, and that the Video output of each video camera is connected to your PC.
2. Start MediaRecorder.
3. Make sure that Video 1 and Video 2 are selected.
4. Click the folder button next to File location and specify where to save the video files. Make sure that you have enough disk space to save video. On average, one video file takes about 10 MB per minute of recording.
5. Under File base name, type a generic (prefix) name for the two files. For example, CO2 test. The program will use this prefix to name the two video files. 5 Recording Video
6. Start recording by clicking the Start Recording button. Release the animal into the test chamber.
7. To stop recording, click the Stop Recording button. The two files, one per video input, are created.

Result

The name of the video file consists of the File base name followed by

the video input name (you can change this in the Settings window), the

date and the time the videos were recorded, and the number of the video camera. For instance, if your File base name is CO2 test, the date is 11 May 2011, and the time 10:54:43, the video files are named:

CO2 test Video 1 11-5-2011 105443 1.avi (for Camera 1) and

CO2 test Video 2 11-5-2011 105443 2.avi (for Camera 2). 6 The EthoVision XT experiment for Track3D

6 The EthoVision XT Experiment For Track3D

In this chapter you find how to create an EthoVision XT experiment for video-tracking. For creating an EthoVision XT experiment for video- recording, see page 44. Make sure that Pixel calibration has been enabled (see page 24). This section contains only the very basic settings that you must adjust in EthoVision. You can customize your experiment in various ways, for example adding trials and independent variables. For more information, see the EthoVision XT Help.

Experiment Settings

1. In EthoVision Xt, create a new default experiment (File > New). Give this experiment a name.
2. Click Experiment Settings.
3. Select:

• Under Video Source, From video file.
• Under Arenas, next to Number of Arenas select 1.
• Under Subjects, next to Number of Subjects per Arena select 1.
• Under Units, next to Unit of distance select mm.

4. Continue with the next section.

Note

The settings described above make it possible to track from one camera view (= Arena) at a time. If you have the Multiple Arena module, you

could in principle select 2 under Arenas, so you can track from both

camera views at the same time. However, this has the limitation that when you do the tracking, you must use the same Detection Settings for both camera views. In some cases the lighting conditions differ between camera views, so that the same Detection Settings may not 6 The EthoVision XT experiment for Track3D be optimal for each camera. For example, when the contrast between animal and background is lower in one camera. In all those situations we advise to select Number of Arenas =1, and define separate Detection Settings for the two camera views. Then, do the tracking for one camera view at a time.

Arena Settings

Drawing the arenas

1. Choose Setup > Arena Settings > New. Enter a name (for example Camera 1 or Camera 2, depending on which camera you use to draw this arena).
2. Click Browse to select the video file(s) depending on your setup:

• If you make video with EthoVision XT, you have one video file for both camera views. Choose this file.
• If you make video with MediaRecorder, you have one file per camera view. Select the file that applies. Click Grab.

3. Right-click the Arena Settings window, just below

the Validate Setup button, and in the message window Set pixel

calibration on, click OK.

Note - If the message says Set pixel calibration off, it means that

calibration is already set to pixel. Click Cancel. 6 The EthoVision XT experiment for Track3D 4. Click 2. Select Shape and Draw the Arena. Draw the arena and make sure that the label points to inside the arena. 5. Repeat the steps 1-4 for the second camera.

Result

You should have two arena settings in your experiment explorer (and two more for calibration that you created earlier, see page 28).

Notes

If you work with the Multiple arena module, you can draw two arenas in the same Arena Settings. With pixel calibration: The origin of the 2D space is the upper left corner of the video. The x-axis points to the right, and the y-axis points downward. The X,Y coordinates of the tracked subjects will be exported in pixels (with decimals). This is an important prerequisite of Track3D.

For more information

See Arena Settings in the EthoVision XT Help.

Trial Control Settings

Adjust the Trial Control Settings to start tracking immediately when

you press the Start Trial button, for both camera 1 and camera 2. This

ensures that the resulting tracks are synchronized. 6 The EthoVision XT experiment for Track3D

Removing the start track condition

1. Choose Setup > Trial Control Settings > Open (or see 1 in Figure 15).
2. Click the second box in the sequence, named Condition In Zone (1), then press Delete.
3. Point the mouse pointer to the center of the first box (Rule Begin -

Start-stop trial), click and drag to the center of the next box (Action

• Start track). The two boxes are connected again.

For more information

See Trial Control in the EthoVision XT Help. Figure 15 Adjust the Trial Control rule to ensure synchronization between the tracks of camera 1 and camera 2. 6 The EthoVision XT experiment for Track3D

Detection Settings

Premise

In most cases you need two Detection Settings, one for camera 1 and one for camera 2. The reason is that the light conditions might differ slightly between camera views, requiring slightly different detection settings.

Creating Detection Settings for one camera view

1. Make sure that the arena settings for the camera you want to use is highlighted in blue in the Experiment Explorer.
2. Choose Setup > Detection Settings > New. Enter a name (for example, the name of the camera that you are going to use) and click OK.
3. In the Detection Settings window, under Video, click Select Video and choose the video file for that camera view (if it is not already selected). If you make video with EthoVision XT, you have one video file for both camera views. Select this video file.
4. Choose the sample rate. For the best results choose the maximum value attainable. (25 (for PAL) and 29.97 (for NTSC) for analog cameras, 30+ for digital cameras).
5. In the Detection Settings window, click Automated Setup and follow the instructions.
6. If detection is not good, in the Detection Settings window, click

Advanced, then:

• Choose the Detection method (Dynamic Subtraction is recommended; for difficult tracing choose Differencing).
• Adjust the contrast if needed. For example, for mosquitoes filmed under IR light conditions, the subject is white on a dark 6 The EthoVision XT experiment for Track3D

background. Therefore, choose Brighter. When the animal is

detected, it is marked with a red dot. - Under Subject Size, enter the Minimum and Maximum subject size. Specify the values in such a way that all groups of pixels smaller than the subject's apparent size (such as system noise) or larger (for instance, reflections) are not confused with the animal. 7. When the subject is well detected, click Save. Repeat the procedure to create Detection settings for the other camera view.

Result

You should have two Detection Settings:

Notes

Make sure that when the animal is not in the arena, EthoVision does not detect any object as the subject. You can see this at the beginning of the video: if the red track jumps from one point to another in the image, it means that it considers pixels of the arena as the subject. Reduce the contrast range, until the red track disappears.

For more information

See Configuring Detection Settings of the EthoVision XT Help.

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Source: Track3D 2 - Reference Manual (March 2025)