Cameras and Sensors
This chapter starts by recalling a camera model sometimes referred to in computer vision and photogrammetry: the pinhole camera. It also discusses its ideal mathematical and approximate implementation by means of a sensor-matrix camera. We recall a few notions from optics. Panoramic sensors are basically defined by the use of “panoramic mirrors”, or controlled motion of such a sensor-matrix camera, which may “shrink” into a sensor-line camera. We conclude with a brief discussion of laser range-finders as an alternative option for a panoramic sensor.
2.1 Camera Models
We consider cameras and sensors at varying levels of abstraction. For example, when using a camera or sensor, we have to take into account as many parameters as possible, to ensure perfect modeling of the image recording situation, and thus high-quality imaging. However, when talking about basic camera or sensor design, we may be more abstract. We start the chapter with such an abstract notion.
2.1.1 Capturing Surface and Central Point
A panoramic camera or sensor captures data about a 3D scene along projection rays. (We neglect for the moment the fact that these rays are actually refracted by some optical system.) In some abstract sense, to be specified for each sensor, these rays map 3D data onto some surface, which can be modeled by a simple geometric shape. For example, a sensor matrix and a “normal optical system” may be understood as defining a light-sensitive rectangle. A fisheye lens may ...