In this paper, we describe a method to photogrammetrically estimate the intrinsic and extrinsic parameters of fish-eye cameras using the properties of equidistance perspective, particularly vanishing point estimation, with the aim of providing a rectified image for scene viewing applications. The estimated intrinsic parameters are the optical center and the fish-eye lensing parameter, and the extrinsic parameters are the rotations about the world axes relative to the checkerboard calibration diagram.
The majority of computer vision applications assumes that the camera adheres to the pinhole camera model. However, most optical systems will introduce undesirable effects. By far, the most evident of these effects is radial lensing, which is particularly noticeable in fish-eye camera systems, where the effect is relatively extreme. Several authors have developed models of fish-eye lenses that can be used to describe the fish-eye displacement. Our aim is to evaluate the accuracy of several of these models. Thus, we present a method by which the lens curve of a fish-eye camera can be extracted using well-founded assumptions and perspective methods. Several of the models from the literature are examined against this empirically derived curve.
The development of electronic vision systems for the automotive market is a strongly growing field, driven in particular by customer demand to increase the safety of vehicles both for drivers and for other road users, including vulnerable road users (VRUs), such as pedestrians. Customer demand is matched by legislative developments in a number of key automotive markets; for example Europe, Japan and the US are in the process of introducing legislation to aid in the prevention of fatalities to VRUs, with emphasis on the use of vision systems. The authors discuss some of the factors that motivate the use of wide-angle and fish-eye camera technologies in vehicles. The authors describe the benefits of using wide-angle lens camera systems to display areas of a vehicle's surroundings that the driver would, otherwise, be unaware of (i.e. a vehicle's blind-zones). However, although wideangle optics provide greater fields of view, they also introduce undesirable effects, such as radial distortion, tangential distortion and uneven illumination. These distortions have the potential to make objects difficult for the vehicle driver to recognise and, thus, potentially have a greater risk of accident. The authors describe some of the methods that can be employed to remove these unwanted effects, and digitally convert the distorted image to the ideal and intuitive rectilinear pin-hole model.
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