Knowledge Base

I See Spikes in the Track

This may occur in the Detection Settings, during data acquisition or in Track Visualization, or in the Integrated Visualization. In most cases you need to correct the arena settings and the detection settings.

Here are a few examples:

1. EthoVision XT tracks light reflections as the subject. Remove sources of reflections by using diffuse, indirect light. Watch the video chapter Set Up the Test Environment in Help > Video Tutorial.
2. EthoVision XT detects some noise at the margin of the well. You can do two things:
   • In the Arena Settings, reduce the size of the arenas, so they do not include the margin of the wall where the animal will never be. This should solve most of the issues.
   • In the Detection Settings, increase the Minimum Subject Size so small groups of pixels will not be detected as the subject. If you work with DanioVision, move the Sensitivity slider to the right. See Advanced detection settings: Subject size (one subject per arena).
3. EthoVision XT finds the subject but it considers it as noise (here in orange), while other objects are detected as the subject. In this case it may suffice to increase the Maximum Subject Size in the Detection Settings. The Maximum value should always be higher than that under Current when the animal is detected correctly. See Advanced detection settings: Subject size (one subject per arena).

You can also remove spikes by editing the tracks (not in DanioVision though). See Edit the Tracks.

Mismatch Between System Time and Tracking Time

This could occur if the video camera provides an unreliable (i.e., fluctuating) frame rate. This may cause a mismatch between the system time and the tracking time. This halts data acquisition.

Industrial cameras such as the Basler cameras have reliable frame rates, while IP cameras and web cams often do not. If the camera is faulty or the driver is not installed properly, unreliable frame rates could occur.

I Only See an Orange Blob

This may be caused by one of the following:

• The second animal is of a color that does not match the current detection settings.
• The reference image is not updated.
• The subject in the second arena is larger than the one in the first arena, and it exceeds the Maximum Subject Size currently set in the Detection Settings. See Advanced detection settings: Subject size (one subject per arena).
• The second arena is set to To Skip. Open the Trial List and set the Acquisition Status for that arena back to Planned.

I Do Not See a Behavior Category in the Manual Scoring Screen

This happens when you open the Manual Scoring screen, then open the Manual Scoring Settings to define a new behavior there, and then return to the Manual Scoring screen.

Solution: Close and reopen the experiment.

Subject Visibility While Observing

In some cases the center point of a small animal makes it hardly visible.

Solution: To hide the center point, choose Track Visualization or Integrated Visualization or Track Editor, and de-select the body points on the right-hand pane. Next, close and re-open the experiment.

Missing Subjects in the Manual Scoring Screen

This happens when one or more subjects have been de-selected in the Track Editor or in one of the Visualization screens.

Solution:

1. Open the Track Editor or the Integrated Visualization.
2. In the Track Plot Settings, under Subjects select the items you are interested in.
3. Return to the Manual Scoring screen.

I Cannot Start Acquisition with a Remote Control

The remote control only works after opening the Acquisition screen and adding a new trial.

To activate the remote control, follow the instructions, see Use a remote control to start and stop acquisition. Contact Noldus Information Technology to obtain a remote control.

IMPORTANT: Before using the remote control, make sure that the Video window or the Playback Control window are on focus. To do so, click anywhere on the Video window or the Playback Control window. Then, operate the remote control.

How Can I Randomize the Start Time of My Trials?

For example, start a one-minute trial every N minutes chosen randomly between 60 and 120.

1. Create a batch file that performs a key press Ctrl+F5, which triggers the start of the trial. In this example, a batch (*.bat) file calls a VBS script (*.vbs) in Windows:

   wscript "C:\vbsprogram.vbs"

2. The VBS script contains the following code:

   Set WshShell = WScript.CreateObject("WScript.Shell")
WshShell.AppActivate "EthoVision"
WScript.Sleep 1000
WshShell.SendKeys "^{F5}"

3. In Windows, open the Task Scheduler and create a new task.
   • In the Triggers tab, specify when a trial should start (e.g. with a random delay).
   • In the Actions tab, select the batch file (*.bat) that triggers the key press Ctrl+F5.
   • See also Start and stop the trial at specific clock times.

Notes:

• When the task is enabled, make sure that the EthoVision XT Acquisition screen is open, and there are no other windows or applications open.
• The end of each trial should be set in the Trial Control Settings.
• In the Trial List, create a list of trials with the appropriate settings already assigned to each trial.
• WScript.Sleep 1000 (1 s delay) ensures that the key press is given when EthoVision XT is in focus.

Cannot Open a GLP Experiment

First, make sure that you have a valid EthoVision XT license that includes the Quality Assurance module. See Modules of EthoVision XT.

This issue could occur if you use EthoVision XT 17 or earlier, and you try to open Acquisition with an EthoVision XT software license. In that case you need a license on a hardware key instead. See Types of EthoVision XT license. Contact Noldus when needed.

How Can I Start Data Acquisition on Multiple Computers Simultaneously?

In the following example, we want to start data acquisition (that is, tracking) in three computers. For this you need three USB-IO boxes and EthoVision XT with the Trial and Hardware Control module in all PCs.

1. Connect the first PC (master) to the other two through the USB-IO boxes: TTL port 1 of the master PC to the TTL port 1 of the second PC, and TTL port 2 of the master PC to the TTL port 1 of the third PC.
2. For each PC, configure the hardware in the Experiment Settings.
3. On the master PC, open the Trial Control Settings and modify the Start-Stop Trial rule in such a way that a TTL "high" signal is sent after the start of tracking to both ports TTL 1 and TTL 2 simultaneously. Make sure that the Action boxes and the Operator are at the right of the Start track box.
4. For each of the other PCs, open the Trial Control Settings and modify the Start-Stop Trial rule in such a way that tracking starts as soon as a TTL "high" signal is detected in TTL port 1. Make sure that you place the Condition box at the left of the Start track box.
5. To start acquisition in all the PCs, click the Start Trial button on the master PC.

As an alternative solution, you could devise a push button that sends TTL signals to each of the USB-IO boxes through UTP cables. Contact Noldus if you need this device.

Source: EthoVision XT 19 Help, Noldus Information Technology