As a trial proceeds, in addition to tracking the animal’s position LimeLight also calculates the length of the animal from nose to the tail base (blue and red cursors in the image to the right). In this case, finding the nose and tail is pretty straightforward, but LimeLight is also extremely accurate even when the animal has its tail curled up around its body, or when the animal is huddled in the corner of the arena.
In the window below is shown a histogram of the animal’s length during the trial. Using the two green cursors, the user then defines 3 different length ranges. Length as a function of time is shown at the bottom of the window, and length as a function of position is shown to the upper right. Each point is color coded according to the defined length ranges. It is also possible to make measures of stretch-attend behavior.
With Length ranges defined in this way, it is then possible to perform a Batch Analysis of length data by Zone or Grid. Possible length parameters are % short, %medium, %long, and mean length for each zone or grid square.
The shortest length is often useful to define rearing, since when the animal rears up toward the camera its profile becomes extremely short.