Knowledge Base

Set Up an Experiment

3.1 Start CatWalk XT

Turn On the CatWalk System

Prerequisites

• If you upgrade from CatWalk XT 8/9, you need the CatWalk Control Unit. Contact your nearest Noldus representative for information.
• If you upgrade from CatWalk XT 10.0, you need to upgrade the firmware of the Control Unit. Contact the Noldus Help desk.
• See the CatWalk XT Assembly Instructions on the installation disc to install the CatWalk system and the Control Unit.

Procedure

1. Check that the on-off switch of the walkway (located on the left side) is turned on. The Control Unit must be connected to the camera, walkway and illuminated ceiling. The Control Unit must also be connected to the CatWalk XT computer via a USB cable if you want to acquire data. For this, your computer must have a USB-C port. Make sure the Control Unit is not connected to the mains socket yet.
2. Connect the Control Unit to the mains socket, and on the Control Unit, turn the switch on. The red lights busy/alive and power on the Control Unit turn on, and the busy/alive light starts flashing. When the Control Unit is finished configuring the LED lights, both red lights turn off. The green and red LED lights of the CatWalk system flash until the correct intensity levels are reached.
3. Make sure you turn on the CatWalk system at least 15 minutes before you start using CatWalk.
4. To turn off the CatWalk system, turn the switch off on the Control Unit.

Start CatWalk XT

After turning on the CatWalk system, it can take a couple of minutes for the camera to be detected. This is indicated by the Acquiring Network icon in the Windows task bar. Note that the yellow triangle does not mean that something went wrong — it means that the PC has not found a network; however, the camera has been detected. Do not start CatWalk XT before this icon appears.

To start CatWalk XT, double-click the CatWalk XT icon on the desktop.

After starting CatWalk XT, you may get a message that the firmware of the Control Unit needs to be upgraded. Contact the Noldus Help desk.

3.2 Set Up the Walkway

This section describes how to configure the software to ensure that recordings will have high quality. Make sure that the camera is in the correct vertical position before proceeding.

Setting up the walkway involves these three steps:

1. Focusing the lens of the camera.
2. Calibrating the walkway so that CatWalk can convert pixels to real-life dimensions.
3. Defining the layout of the walkway by outlining the area inside the corridor that you want to record.

For the first two steps, a dedicated tool is used: the calibration card. It must be placed in the walkway, separated from the corridor walls and positioned somewhere in the middle of the glass plate.

All three functionalities can be accessed via the Setup menu or the Setup Walkway Tasks.

Focus Assist

The camera lens has two rings that can be turned: the aperture, which controls brightness, and the focus ring, which controls sharpness.

Before focusing, make sure:

• The aperture of the lens is fully opened so that the image appears bright and cannot be made brighter.
• The calibration card is placed somewhere in the middle of the walkway.
• You can see the PC screen when the camera is being focused.

To start the Focus Assist, do one of the following:

• In the Application Startup Tasks window, click Setup the Walkway and then Focus Assist.
• Choose Setup > Focus Assist.
• Click the Focus Assist icon in the toolbar.

The top image shown is the original image from the camera. The bottom image shows only the sharp parts of the original image and is therefore a good indication of overall sharpness — the more white it shows, the sharper the image is.

The crop buttons can be used to crop or uncrop the images. They have no effect on the reported values, colors, or sharpness indicator.

The sharpness indicator shows the percentage of the maximum reachable sharpness. If the focusing procedure was disturbed in some way, it may be impossible to get the indicator to reach nearly 100%. In this case, the procedure must be redone: turn the focus ring slightly out of focus, close the dialog, then reopen it and repeat the procedure.

Calibrate the Walkway

After focusing the camera correctly, the walkway must be calibrated. Keep the calibration card in the same position in the walkway as it was used to focus the lens.

To start the calibration, do one of the following:

• In the Application Startup Tasks window, click Setup the Walkway and then Calibrate the Walkway.
• Choose Setup > Calibrate Walkway.
• Click the Calibrate Walkway icon in the toolbar.
• Click Next in the Focus Assist dialog.

In the Calibrate Walkway window, click Auto Calibration. If no error warning occurs, the calibration is created automatically. Press OK to save it, or Next/Previous to go to the next or previous step of the setup. Note that pressing Next or Previous also saves the calibration. Pressing Cancel discards the changes.

If an error is shown:

• Make sure that the calibration card is in the center of the walkway and is the only object on the walkway.
• Make sure the red light is working correctly.
• Make sure the camera lens aperture is fully opened.
• The calibration can be set manually, but it is highly recommended not to do so. In general, if auto calibration fails, something is wrong with the setup. A message appears indicating what is wrong and how to fix it.

Define the Layout of the Walkway

To define the walkway layout, do one of the following:

• In the Application Startup Tasks window, select Setup the Walkway and then click Define the Layout of the Walkway.
• Choose Setup > Define Walkway.
• Click the Define Walkway icon in the toolbar.
• Click Next in the Calibrate Walkway dialog.

In the Define Walkway window, you see the full camera image. If you do not see an image, open the camera's aperture and make sure the camera is focused correctly.

1. Press Detect Walkway. When no errors are reported, the walkway sides are found and a walkway covering 70% of the length of the walkway is defined automatically. You can make the walkway rectangle longer and reposition it. In general, moving or enlarging vertically should not be needed. If walkway detection fails, a message is shown. Failure of detection can be caused by other objects on the walkway, sub-optimal lighting conditions, or side walls of the corridor that are not aligned with the camera or with each other. These errors must be fixed before proceeding.
2. If desired, the walkway definition can be changed manually. Position the mouse pointer over the rectangle so it becomes a four-headed arrow, then drag the rectangle to the top-left corner of the area you want to outline.
3. Position the mouse pointer at the bottom-right corner of the rectangle so the pointer becomes a resize pointer. Drag the bottom-right corner to the bottom-right corner of the area of interest on the walkway. Make sure that all sides of the rectangle are visible within the camera view. Press OK to save the changes or Cancel to discard them.

General Remarks on Setup

When all three parts of the setup are successfully completed, the setup is correct: the camera is focused, the walkway is calibrated, and the walkway definition is specified.

For an experiment with a specific hardware configuration, you only need to set up the walkway once, unless something changes to the hardware setup (for example, the camera was moved or the width of the corridor was changed). When you close an experiment, the layout of the walkway and the calibration are stored within the application. The next time you open CatWalk, the Application Startup Tasks window shows the last date and time the walkway was defined and calibrated.

In the walkway calibration and definition dialogs, buttons for Previous and Next are available. When pressed, the changes are stored.

After setting up the walkway, the side walls can still move slightly during normal use. Opening and closing the red light cover, or accidentally touching the side walls, can relocate them. When data acquisition is started, an additional check for the walkway is offered.

Create a New Experiment

1. To create a new experiment, do one of the following:
   • In the Application Startup Tasks window, click Create a New Experiment.
   • Choose File > New Experiment or press Ctrl+N.
   • Click the New Experiment icon in the toolbar.
2. In the New Experiment window, enter the name of the experiment. The name cannot contain any of the following characters: / : * ? \ " < > | ' & . ;
3. Select a Setup Profile from the list.
4. Optionally, browse to the location where you want to save your experiment. Do not save your experiment to a USB stick, as this might result in a corrupt experiment.
5. Optionally, add a description and edit the name in the Created By field.
6. Click the Create Experiment button.

3.3 Specify the Experiment Settings

Experiment Settings Screen

In the Experiment Settings screen, you define the animal type, time points, treatment groups, and run criteria. These variables and values remain constant throughout the experiment but can potentially affect the outcome of the experiment.