Knowledge Base

Prepare Data Acquisition

Preparing Data Acquisition involves specifying:

• Detection settings – To distinguish between paw prints and background noise. See below.
• Acquisition settings – To specify settings for acquired runs. See the Acquisition Settings section.

Detection Settings

The aim of the Detection Settings is to achieve an optimal intensity range for the paw prints and to filter out background noise. This is done by putting an animal of average weight on the walkway and then adjusting the Camera Gain and Green Intensity Threshold. Additionally, you can adjust the intensity of the Green Walkway Light and/or Red Ceiling Light. You can have multiple Detection Settings Profiles, for example, one for mice and one for rats.

Note: Please make sure you turn the lights off before configuring the Detection Settings or turn on red ambient lighting.

To configure the Detection Settings:

1. First, put an animal on the walkway and make sure that it stays within the camera view. Also make sure the illuminated ceiling is lowered.
2. In the Detection Settings window, click the Reset Prints button to 'clean' the Prints view.
3. Click the Start Auto Detect button. The program now automatically adjusts both Camera Gain and Green Intensity Threshold in consecutive steps to achieve the optimal range. Adjustment of the Camera Gain results in a value for Maximum Green Intensity between 197 and 203 based on the prints in the Print view. Adjustment of the Green Intensity Threshold ensures that prints that do not contain pixels with an intensity above the Minimum Green Intensity are removed from the Print view.
4. When Auto Detection is finished successfully, a message appears. If detection of the toes is important (if you want to classify toes in the Interactive Footprints Measurement to calculate the Sciatic Functional Index), check whether manually adjusting the Camera Gain and Green Intensity Threshold might result in even better detection of the toes.
5. Optionally, increase the intensity of the Green Walkway Light and/or decrease the intensity of the Red Ceiling Light (with steps of 0.1) to further optimize detection of paws. Now re-do auto detection (step 1). As a rule of thumb, the Camera Gain value should be between 5 and 12 dB.
6. Click OK when you are done.

Acquisition Settings

Choose Setup > Acquisition Settings. In the Acquisition Settings, you can set the following:

Background Image

Here you can view the Background Image that you snap in the Acquisition pane.

Run Settings

• Auto abort runs when the duration exceeds ... seconds – When you select this option, data acquisition is automatically stopped when a run exceeds the set number of seconds. This option is different from the Maximum run duration in the Experiment Settings. When an animal exceeds the Maximum run duration, acquisition is not aborted but the run labeled 'non-compliant'.
• Discard auto aborted runs – When you select this option, runs that are automatically aborted are removed.
• Discard user aborted runs – When you select this option, runs for which acquisition was manually stopped are removed.
• Discard runs not compliant with the Run Criteria – When you select this option, runs that do not comply with the Run criteria are automatically removed.
• Discard incomplete prints at the start and end of a run – An incomplete print can result from a paw that is put on the edge of the defined walkway, either at the start or end of a run. This can result in incorrect data: for example, the calculated print area of such a paw underestimates the actual print area. When you select this option, incomplete prints are not included in the classification. See the section Run Settings in the CatWalk XT 11.0 Reference Manual for more details.

Sound Feedback

• Run start (1 beep) – When selected, you get one system beep when acquisition starts.
• Run stop (2 beeps) – When selected, you get two system beeps when acquisition stops.
• Error (3 beeps) – When selected, you get three system beeps when an error occurs (for example, if the camera connection gets lost).

When you are finished with the Acquisition Settings, click OK.

Proceed to Acquisition by clicking >> Open Acquisition at the bottom-right corner of the screen or choose Acquire menu > Open Acquisition.

Acquire the Data

We recommend that you acquire the data with the lights in the test room turned off, or under ambient red light conditions. Make sure that the red light is not situated straight above the camera. Also make sure the illuminated ceiling is lowered.

To carry out Data Acquisition, do the following:

1. Under Trial Selection, select an existing trial or create a new trial. You can also select a specific trial in the Experiment Explorer; right-click a trial and select Acquire Runs.
2. In the Video section, click the Snap Background button to snap an image of the empty walkway.
3. Optionally, the walkway can be checked if it is still OK. If, for example, the side walls are moved, the walkway detection should be redone. See setting up the walkway.
4. Click the Start Acquisition button (or press Page Up).
5. Put the animal on the walkway (ensure it is not in the camera view). To do this, put the animal in from the side. Recording a run starts automatically as soon as the animal's body contour is detected in the camera image. Recording a run stops automatically when the animal has completely disappeared from the camera image.
6. Data Acquisition stops:
   • Automatically, when the minimum number of compliant runs (as set in the Experiment Settings) has been acquired.
   • When you click the Stop Acquisition button (or press Page Down).
7. What do you want to do next?
   • Acquire the next trial – Select Acquire Next Trial in the Acquisition Finished Tasks window and go back to step 1 above.
   • Create and acquire a new trial – Select Acquire New Trial in the Acquisition Finished Tasks window or select create a new trial from the list under Trial Selection.
   • Classify runs – Select Classify Runs in the Acquisition Finished Tasks window or click >> Classify Runs at the bottom-right of the Acquisition screen.
   • Review runs – Select Review Runs in the Acquisition Finished Tasks window and under Video, select a run from the View list.
   • Remove runs – Close the Acquisition Finished Tasks window, click a run in the list with Acquired Runs and click the Remove Run(s) button at the bottom. Alternatively, in the Experiment Explorer, right-click a run and select Remove.

Source: CatWalk XT 11.0 Quick Start Guide, Noldus Information Technology