A camera able to see in all directions. There are essentially two different methods to obtain a very wide field of view: the older one involves the use of a special type of lens, usually referred to as fisheye lens, while the other one uses in conjunction rectilinear lenses and mirrors. Lenses obtained in the latter case are usually called catadioptric lenses and the camera-lens ensemble is referred to as catadioptric camera
Published in Chapter:
Hybrid Dual Camera Vision Systems
Stefano Cagnoni (Università degli Studi di Perugia, Italy), Monica Mordonini (Università degli Studi di Perugia, Italy), Luca Mussi (Università degli Studi di Perugia, Italy), and Giovanni Adorni (Università degli Studi di Genova, Italy)
Copyright: © 2009
|Pages: 5
DOI: 10.4018/978-1-59904-849-9.ch125
Abstract
Many of the known visual systems in nature are characterized by a wide field of view allowing animals to keep the whole surrounding environment under control. In this sense, dragonflies are one of the best examples: their compound eyes are made up of thousands of separate light-sensing organs arranged to give nearly a 360° field of vision. However, animals with eyes on the sides of their head have high periscopy but low binocularity, that is their views overlap very little. Differently, raptors’ eyes have a central part that permits them to see far away details with an impressive resolution and their views overlap by about ninety degrees. Those characteristics allow for a globally wide field of view and for accurate stereoscopic vision at the same time, which in turn allows for determination of distance, leading to the ability to develop a sharp, three-dimensional image of a large portion of their view. In mobile robotics applications, autonomous robots are required to react to visual stimuli that may come from any direction at any moment of their activity. In surveillance applications, the opportunity to obtain a field of view as wide as possible is also a critical requirement. For these reasons, a growing interest in omnidirectional vision systems (Benosman 2001), which is still a particularly intriguing research field, has emerged. On the other hand, requirements to be able to carry out object/pattern recognition and classification tasks are opposite, high resolution and accuracy and low distortion being possibly the most important ones. Finally, three-dimensional information extraction can be usually achieved by vision systems that combine the use of at least two sensors at the same time. This article presents the class of hybrid dual camera vision systems. This kind of sensors, inspired by existing visual systems in nature, combines an omnidirectional sensor with a perspective moving camera. In this way it is possible to observe the whole surrounding scene at low resolution, while, at the same time, the perspective camera can be directed to focus on objects of interest with higher resolution.