Presenter: Pichaya Lertvilai (University of California San Diego)

Description:
In situ free-space observation of traits of aquatic organisms, including size and motility, requires three-dimensional measurements that are commonly done with a stereoscopic imaging system. However, to observe these traits of small zooplankton, the imaging system requires relatively high magnification, which results in a small overlapping volume between the two cameras of a conventional stereoscopic system. A system that can provide a larger overlap would be a great advantage to zooplankton research. Towards this goal, we implement a stereoscopic setup that utilizes a tilted lens approach, known as the Scheimpflug principle, to increase the common imaging volume of two cameras. The system was deployed in the field to observe aquatic corixid insects.  After calibration and image processing, we were able to resolve insect body length and swimming speed. Analysis indicates that the relationship between the body length and the swimming speed of the corixid insects is linear in the log-log space.  Our results demonstrated that the stereoscopic system with tilted lenses can be used to observe key traits of small aquatic organisms in an ecological context that can provide a trait-based analysis to zooplankton ecology.