Camera modeling and calibration are essential tasks in modern optics.
Conventionally, the pinhole model is adopted with a further extension
for lens distortion. However, pinhole and distortion models are
mutually dependent; thus, the standard approach induces systematic
camera calibration errors. This research presents a unifying distorted
pinhole camera model that includes a telecentric, distortion-free
pinhole, and radial lens distortion as particular cases. An iterative
calibration method based on the derived distorted pinhole model is
proposed, and experimental evaluation by calibrating a camera with
high radial distortion is performed. The calibration results are
compared with the standard and fisheye models using a well-known
commercial camera calibrator software. The proposed method outperforms
the standard model and achieves accuracy comparable to the fisheye
model, and the proposed approach is a versatile and accurate tool for
diverse optical metrology applications.
An adaptive joint transform correlator for real-time pattern recognition is presented. A reference image for the correlator is generated with a new iterative algorithm. The training algorithm is based on synthetic discriminant functions. The obtained reference image contains the information needed to reliably discriminate a target against known false objects and a cluttered background. Calibration lookup tables of all optoelectronics elements used are included in the design of the adaptive joint transform correlator. Two methods for the implementation of the proposed joint transform correlator in an optodigital setup are considered. Experimental results are provided and compared with those of computer simulations.
Abstract. An operator-based approach for the study of homogeneous coordinates and projective geometry is proposed. First, some basic geometrical concepts and properties of the operators are investigated in the oneand two-dimensional cases. Then, the pinhole camera model is derived, and a simple method for homography estimation and camera calibration is explained. The usefulness of the analyzed theoretical framework is exemplified by addressing the perspective correction problem for a camera document scanning application. Several experimental results are provided for illustrative purposes. The proposed approach is expected to provide practical insights for inexperienced students on camera calibration, computer vision, and optical metrology among others.
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