Parallax in Electric Field Imagery

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This project deals with the transfer of the concept of parallax from geometrical optics to the domain of electric fields for the localization and inspection of objects in fluids. Weakly electric fish, which serve as biological models in this project, form dipole-like electric fields in the tail region with the help of specialized muscle cells. The electric field is perceived with specialized sensory cells (mormyromasts) in the skin surface. Objects in the environment lead to field distortions, whose electrical images on the skin surface allow the fish to locate the objects, differentiate material properties and distinguish animate from inanimate objects. The ability to "see electrically" allows them to display complex behaviors even in total darkness or in opaque water. Recent studies show that weakly electric fish principally use parallax based on their electrical sense to distinguish distant from near objects even at different sizes. Here both their ego-motion, characterized by forward and backward swimming movements as well as the active movement of the Schnauzenorgan and tail in the sense of a controlled influence of the local field course of the self-emitting field seems to play a role. On the biological side, this project investigates the influence of active changes in body part positions on the generated electric field in real-world experiments. At the same time, a theoretical framework will be developed which describes, on the basis of the known electric field theory, how local field changes can be specifically generated by introducing active monopoles and passive field influencing elements. The passive field influencing elements and their control will be compared with the corresponding counterparts from the biological example in addition to theoretical and simulative considerations. On the basis of the targeted local field influence, the concept of parallax is then transferred from geometrical optics to the domain of electric fields. In optics, parallax requires an imaging system (lenses). These imaging properties are achieved on the electrical field side by local field changes, since these changes influence how the field-distorting effects of objects to be localized are expressed on a sensor phalanx. The project uses simulation and real laboratory set-ups up to 2D sensor arrangements. At the same time, the behaviour of free-moving, weakly electric fish of two species will be empirically investigated to understand whether the fish use certain movement patterns to optimize the electrical parallax effect and thus support depth perception within their natural behavioural repertoire.