Visualizing and quantifying movement from pre-recorded videos: The spectral time-lapse (STL) algorithm

When studying animal behaviour within an open environment, movement-related data are often important for behavioural analyses. Therefore, simple and efficient techniques are needed to present and analyze the data of such movements. However, it is challenging to present both spatial and temporal information of movements within a two-dimensional image representation. To address this challenge, we developed the spectral time-lapse (STL) algorithm that re-codes an animal’s position at every time point with a time-specific color, and overlays it with a reference frame of the video, to produce a summary image. We additionally incorporated automated motion tracking, such that the animal’s position can be extracted and summary statistics such as path length and duration can be calculated, as well as instantaneous velocity and acceleration. Here we describe the STL algorithm and offer a freely available MATLAB toolbox that implements the algorithm and allows for a large degree of end-user control and flexibility

Analyzing video produced by a stationary surveillance camera

Developing visual tools that support data analysis in a specific application domain requires a careful investigation in order to understand needs and expectations of people who will use such tools. The domain experts addressed in this paper are chemists specialized in environmental data analysis. Their main activity is to detect and monitor chemical compounds in the air through many devices in order to detect anomalies or prevent risks. One of the main problems that chemists face is the analysis of the huge amount of data produced by devices. They perform explorative data analysis and are willing to use software tools that can help them to get insights from data. This paper reports the experience in working with chemists to identify interactive visual tools that can be useful for their purposes. It provides insights on the difficulty of creating systems that users find really useful for their work, even when users participate in the design team. Because of the complexity of the considered problem and the fact that people are unable to make explicit all their needs and requirements, the identification of proper tools resulted very challenging