Experiments
The experiment is performed using a system of three synchronized high speed cameras recording the same flock/swarm from different points of view. Image sequences are then analyzed to reconstruct the three dimensional trajectory of each individual within the group, using stereo matching and other computer vision techniques. Further analysis of the trajectories should lead to a better understanding of the fundamental interaction rules between individuals. More details about our computer vision and tracking research can be found here.
Starling flocks in Rome can be observed starting from middle to late November until the beginning of February to the beginning of March, depending on the weather and temperature during the winter. They aggregate at dusk while travelling from the country side surrounding Rome into the city to roost. Roosting sites are scattered throughout the city including Cimitero del Verano, Laghetto dell’EUR, Termini, and near Circo Massimo. Some of the most impressive and large aerial displays can be seen in the first two listed locations.
Our search for midge swarms has taken us to many of the public parks within Rome including Riserva Naturale Valle dell’Aniene, Villa Paganini, Villa Torlonia, Parco dell’Acquedotto, Villa Ada, Laghetto dell’EUR and Ponte Tazio. Basically any place with an aquatic or semiaquatic habitat (the larval stage requires water for development) is where midges can be found. Lighting to capture the midges is tricky, as we depend on the backscattering of light off their wings to illuminate each individual. This means that the sun is generally in front of the cameras, which effectively reduces the contrast of the midges. Midges are generally active throughout the day, however due to the requirement of backlighting it is only feasible to acquire image sequences at dawn (yes we have gone out at dawn) and at dusk. As part of our ongoing study of midge swarms, at the end of each experimental session we capture and preserve several midges that are part of a swarm. Back in the lab, we use a combination of a stereoscopic and a compound microscope to classify the midges. More details about midges taxonomy can be found here.
The COBBS Laboratory is housed on the 4th floor of the Fermi Building, Sapienza University; it is our main lab space and houses the experimental team. The activities of CoBBS Lab are indeed not limited to the field experiments. Many experimental activities, such as the calibration of the internal parameters of the cameras (i.e. focal length, position of the centre of the image, distortion coefficients) as well as tests on the synchronization and the accuracy of the camera system, need to be periodically performed in the laboratory to guarantee the high quality of the data.