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The Physical Environment and the Physiology of Flight
Published in Harry W. Orlady, Linda M. Orlady, John K. Lauber, Human Factors in Multi-Crew Flight Operations, 2017
Harry W. Orlady, Linda M. Orlady, John K. Lauber
Most people believe that stereo vision is the most important depth cue. The stereo cue results from the fact that we normally have two eyes sensing the same object. The retinal images formed by the two eyes are not focused precisely on the same part of the retinal mosaic and, while there is no doubt that this information provides very valuable knowledge, there is great uncertainty about just how the brain processes this data. Despite the acknowledged value of stereo vision in depth perception, there is no longer any question that people with only one eye (monocular vision) also are able to function effectively in tasks that require a high degree of depth perception. Wiley Post, a pioneer US high-altitude pilot and the first man to fly around the world alone, was an outstanding example for he had only one good eye. He wore a patch over the other.
Camera calibration method based on circular array calibration board
Published in Systems Science & Control Engineering, 2023
Haifeng Chen, Jinlei Zhuang, Bingyou Liu, Lichao Wang, Luxian Zhang
On the basis of the different number of vision sensors, existing camera calibration methods can be divided into monocular vision camera calibration, binocular vision camera calibration, and multi-vision camera calibration. On the basis of the different calibration methods, the camera calibration methods can usually be divided into three types namely, calibration method based on calibration template (Tsai, 1986), calibration method based on active vision (Maybank & Faugeras, 1992), and camera self-calibration method (Zhang & Tang, 2016). The so-called calibration method based on calibration template uses a calibration object with a known structure and high-precision as a spatial reference, establishes the constraint relationship between camera model parameters through the correspondence between spatial points, and solves these parameters on the basis of the optimal algorithm. parameter. Typical representative methods include direct linear transformation (DLT) (Abdel-Aziz, 2015) and Tsai two-step method (Tsai, 1986). The calibration method based on the calibration template can obtain calibration with relatively high accuracy, but the processing and maintenance of the calibration object is complicated, and setting the calibration object in the harsh and dangerous actual operating environment is difficult. The camera calibration method based on active vision refers to obtaining multiple images by actively controlling the camera to perform some special motions on a platform that can be precisely controlled and using the images collected by the camera and the motion parameters of the controllable camera to determine the camera parameters. The representative method of this class is the linear method based on two sets of three orthogonal motions proposed by Massonde (Sang, 1996). Subsequently, Yang et al. proposed an improved scheme, that is, based on four groups of plane orthogonal motion and give groups of plane orthogonal motion, the camera is linearly calibrated by using the pole information in the image (Li et al., 2000; Yang et al., 1998). This calibration method is simple to calculate and can generally be solved linearly and has good robustness, but the system cost is high, and it is not applicable when the camera motion parameters are unknown or the camera motion cannot be precisely controlled. In recent years, the camera self-calibration method proposed by many scholars can independently calibrate the reference object by only using the correspondence between multiple viewpoints and the surrounding environment during the natural movement of the camera. This method has strong flexibility and high applicability, and it is usually used for camera parameter fitting based on absolute quadric or its dual absolute quadric (Wu & Hu, 2001). However, this method belongs to nonlinear calibration, and the accuracy and robustness of the calibration results are not high.