Knowledge Base

2D Footprint Intensities

Click on the 2D Footprint Intensities tab.

The 2D Footprint Intensities tab plots the print intensities of each paw print in a single image. The solid red line represents the maximum intensity in a frame, the filled, colored area under the red line represents the mean intensity of the paw.

The 2D Footprint Intensities plot displays the prints from left to right irrespective of the animal's actual walking direction.

When you right-click the 2D Footprint Intensities plot, you can select one of two options:

• Save to File. This saves the 2D Footprint Intensities plot to an image file (*.png).
• Copy to Clipboard. This copies the 2D Footprint Intensities plot to the clipboard.

Footfall Patterns

Click the Footfall Patterns tab.

The Footfall Patterns diagram shows the order in which the paws (represented by colored dots) were placed on the glass plate. The Footfall Patterns are displayed from left to right, irrespective of the animal's actual walking direction.

The colors of the dots indicate the following:

Orange - Not Taken into Account

Orange dots indicate paw placements that are not taken into account when determining a footfall pattern. This often occurs to the first and last paw prints.

In the example below, the first paw placement, LF, occurs again within a 4-paw sequence (see the fourth dot in the run). A pattern like LF-LH-RF-LF is clearly not a footfall pattern. Therefore, the LF paw placement is ignored and the software starts looking for patterns from the next paw placement. In this case, the next paw placement is LH, which is followed by RF-LF-RH. Together, they form a recognized footfall pattern, indicated with CA.

Similarly, paw placements at the end of the run can be excluded. After the last valid pattern LH-RF-LF-RH has been found (see the last CA in the run), three paw placements are left: RF, LH and RH. They form an incomplete pattern, which is excluded from the results.

Blue - Start of a Pattern

Paws at the beginning of a recognized footfall pattern. It is always followed by three green dots.

Green - Part of a Pattern

Paws that are at the second, third and fourth place in a recognized footfall pattern.

Purple - Not Part of a Pattern

These paw placements are determined as not being part of a footfall pattern. They are usually in the middle of the run, between two valid patterns.

In the following example, the paw LF is repeated within a sequence of 4 paw placements. The sequence LF-LH-RF-LF is not recognized as a valid pattern. So the paw placement LF is marked with a Not Part of a Pattern dot and the software resumes searching from the next paw placement, in this case LH, which is detected as the start of a CA pattern (LH-RF-LF-RH).

How Footfall Patterns Are Labeled

Consider a generic footfall pattern found in a run, like LH-RF-LF-RH. The starting paw placement LH is marked with a blue dot.

If this pattern LH-RF-LF-RH is repeated immediately after the first one (LH-RF-LF-RH-LH-RF-LF-RH), additional patterns can be recognized:

• Starting from the second placement, RF: RF-LF-RH-LH
• Starting from the third placement, LF: LF-RH-LH-RF
• Starting from the fourth placement, RH: RH-LH-RF-LF

This "family" of patterns is marked with the label CA (Cruciate A). The grouping of patterns into "families" is also the reason why CatWalk XT reports only 6 patterns (CA, CB, AA, AB, RA, RB) out of a total of 24 possible combinations. This makes classification independent of which paw comes first at the beginning of a run.

The predefined footfall pattern labels are (note that any of the paw prints within a sequence can be the starting point, marked with the blue dot):

• Cruciate Patterns:
  • CA, for the paw sequence RF-LF-RH-LH
  • CB, for LF-RF-LH-RH
• Alternate Patterns:
  • AA, for RF-RH-LF-LH
  • AB, for LF-RH-RF-LH
• Rotate Patterns:
  • RA, for RF-LF-LH-RH
  • RB, for LF-RF-RH-LH

When initial contact of two paws coincides in a frame, the paw with the largest surface area in that frame is considered to have been placed first. In the unlikely event that the surface areas of these paws are equal, the following order of placement is used: LF-LH-RF-RH.

Paws that are currently visible in the Video window are marked with a dotted circle in the Footfall Patterns diagram.

Export the Visualizations

Right-click the Footfall Patterns diagram and choose one of the two options:

• Save to File. This saves the Footfall Patterns diagram to an image file (*.png).
• Copy to Clipboard. This copies the Footfall Patterns diagram to the clipboard.