Mimicking honeybee eyes with a 280 degrees field of view catadioptric imaging system.

We present a small single camera imaging system that provides a continuous 280 degrees field of view (FOV) inspired by the large FOV of insect eyes. This is achieved by combining a curved reflective surface that is machined into acrylic glass with lenses covering the frontal field that otherwise would have been obstructed by the mirror. Based on the work of Seidl (1982 PhD Thesis Technische Hochschule Darmstadt), we describe an extension of the 'bee eye optics simulation' (BEOS) model by Giger (1996 PhD Thesis Australian National University) to the full FOV which enables us to remap camera images according to the spatial resolution of honeybee eyes. This model is also useful for simulating the visual input of a bee-like agent in a virtual environment. The imaging system in combination with our bee eye model can serve as a tool for assessing the visual world from a bee's perspective which is particularly helpful for experimental setups. It is also well suited for mobile robots, in particular on flying vehicles that need light-weight sensors.

Rugged, obstruction-free, mirror-lens combination for panoramic imaging.

We present a new combination of lenses and reflective surfaces for obstruction-free wide-angle imaging. The panoramic imaging system consists of a reflective surface machined into solid Perspex, which together with an embedded lens, can be attached to a video camera lens. Unlike vision sensors with a single mirror mounted in front of a camera, the view in the forward direction (i.e., the direction of the optical axis) is not obstructed. Light rays contributing to the central region of the image are refracted at a centrally positioned lens and at the Perspex enclosure. For the outer image region, rays are reflected at a mirror surface of constant angular gain machined into the Perspex and coated with silver. The design produces a field of view of approximately 260 degrees with only a small separation of viewpoints. The shape of the enclosing Perspex is specifically designed in order to minimize internal reflections.

Theory of arachnid prey localization.

Sand scorpions and many other arachnids locate their prey through highly sensitive slit sensilla at the tips (tarsi) of their eight legs. This sensor array responds to vibrations with stimulus-locked action potentials encoding the target direction. We present a neuronal model to account for stimulus angle determination using a population of second-order neurons, each receiving excitatory input from one tarsus and inhibition from a triad opposite to it. The input opens a time window whose width determines a neuron's firing probability. Stochastic optimization is realized through tuning the balance between excitation and inhibition. The agreement with experiments on the sand scorpion is excellent.