Two-point calibration method for zoom camera with approximate focal-invariant radial distortion model

2021 ◽  
Author(s):  
Pei An ◽  
Jie Ma ◽  
Tao Ma ◽  
Bin Fang ◽  
Kun Yu ◽  
...  
Keyword(s):  
Calibration Method ◽  
Distortion Model ◽  
Radial Distortion

Pixel-wise distortion model and its calibration method for AMCW LiDAR

2021 ◽  
Author(s):  
Junwoo Jason Son ◽  
Youngbin Son ◽  
Byeongho Song ◽  
Soohee Han
Keyword(s):  
Calibration Method ◽  
Distortion Model

scholarly journals DoF-Dependent and Equal-Partition Based Lens Distortion Modeling and Calibration Method for Close-Range Photogrammetry

Sensors ◽  
2020 ◽  
Vol 20 (20) ◽  
pp. 5934
Author(s):  
Xiao Li ◽  
Wei Li ◽  
Xin’an Yuan ◽  
Xiaokang Yin ◽  
Xin Ma
Keyword(s):  
Optical Axis ◽  
Focal Length ◽  
Calibration Method ◽  
Depth Of Field ◽  
Model Parameters ◽  
Lens Distortion ◽  
Camera Model ◽  
Distortion Model ◽  
Manual Adjustment ◽  
Close Range

Lens distortion is closely related to the spatial position of depth of field (DoF), especially in close-range photography. The accurate characterization and precise calibration of DoF-dependent distortion are very important to improve the accuracy of close-range vision measurements. In this paper, to meet the need of short-distance and small-focal-length photography, a DoF-dependent and equal-partition based lens distortion modeling and calibration method is proposed. Firstly, considering the direction along the optical axis, a DoF-dependent yet focusing-state-independent distortion model is proposed. By this method, manual adjustment of the focus and zoom rings is avoided, thus eliminating human errors. Secondly, considering the direction perpendicular to the optical axis, to solve the problem of insufficient distortion representations caused by using only one set of coefficients, a 2D-to-3D equal-increment partitioning method for lens distortion is proposed. Accurate characterization of DoF-dependent distortion is thus realized by fusing the distortion partitioning method and the DoF distortion model. Lastly, a calibration control field is designed. After extracting line segments within a partition, the de-coupling calibration of distortion parameters and other camera model parameters is realized. Experiment results shows that the maximum/average projection and angular reconstruction errors of equal-increment partition based DoF distortion model are 0.11 pixels/0.05 pixels and 0.013°/0.011°, respectively. This demonstrates the validity of the lens distortion model and calibration method proposed in this paper.

RATIONAL RADIAL DISTORTION MODELS OF CAMERA LENSES WITH ANALYTICAL SOLUTION FOR DISTORTION CORRECTION

2004 ◽  
Vol 01 (02) ◽  
pp. 135-147 ◽  
Author(s):  
LILI MA ◽  
YANGQUAN CHEN ◽  
KEVIN L. MOORE
Keyword(s):  
Analytical Solution ◽  
Polynomial Approximation ◽  
Distortion Correction ◽  
Camera Model ◽  
Distortion Model ◽  
Radial Distortion ◽  
New Class ◽  
Comparable Accuracy ◽  
The Common ◽  
Distortion Parameters

The common approach to radial distortion is by the means of polynomial approximation, which introduces distortion-specific parameters into the camera model and requires estimation of these distortion parameters. The task of estimating radial distortion is to find a radial distortion model that allows easy undistortion as well as satisfactory accuracy. This paper presents a new class of rational radial distortion models with easy analytical undistortion formulae. Experimental results are presented to show that with this class of rational radial distortion models, satisfactory and comparable accuracy can be achieved.

Further Study on Radial Distortion Model for Photographic Objective

2008 ◽  
Vol 28 (10) ◽  
pp. 1930-1933 ◽  
Author(s):  
艾莉莉 Ai Lili ◽  
袁峰 Yuan Feng ◽  
丁振良 Ding Zhengliang
Keyword(s):  
Distortion Model ◽  
Radial Distortion

scholarly journals A Decoupled Calibration Method for Camera Intrinsic Parameters and Distortion Coefficients

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Kun Yan ◽  
Hong Tian ◽  
Enhai Liu ◽  
Rujin Zhao ◽  
Yuzhen Hong ◽  
...  
Keyword(s):  
Real Data ◽  
Calibration Method ◽  
Intrinsic Parameters ◽  
Radial Distortion ◽  
Vision Measurement ◽  
Field Of Vision ◽  
Marquardt Algorithm ◽  
Calibration Accuracy ◽  
Camera Intrinsic Parameters ◽  
Division Model

Camera calibration is a necessary process in the field of vision measurement. In this paper, we propose a flexible and high-accuracy method to calibrate a camera. Firstly, we compute the center of radial distortion, which is important to obtain optimal results. Then, based on the radial distortion of the division model, the camera intrinsic parameters and distortion coefficients are solved in a linear way independently. Finally, the intrinsic parameters of the camera are optimized via the Levenberg-Marquardt algorithm. In the proposed method, the distortion coefficients and intrinsic parameters are successfully decoupled; calibration accuracy is further improved through the subsequent optimization process. Moreover, whether it is for relatively small image distortion or distortion larger image, utilizing our method can get a good result. Both simulation and real data experiment demonstrate the robustness and accuracy of the proposed method. Experimental results show that the proposed method can be obtaining a higher accuracy than the classical methods.

scholarly journals A REVIEW OF THE ONE-PARAMETER DIVISION UNDISTORTION MODEL

2021 ◽  
Vol V-1-2021 ◽  
pp. 89-96
Author(s):  
B. Erdnüß
Keyword(s):  
Image Plane ◽  
Distortion Parameter ◽  
Distortion Model ◽  
Radial Distortion ◽  
Projective Invariant ◽  
Algebraic Properties ◽  
The One ◽  
Metric Distance ◽  
Straight Lines ◽  
Line Space

Abstract. The one-parameter division undistortion model by (Lenz, 1987) and (Fitzgibbon, 2001) is a simple radial distortion model with beneficial algebraic properties that allows to reason about some problems analytically that can only be handled numerically in other distortion models. One property of this distortion model is that straight lines in the undistorted image correspond to circles in the distorted image. These circles are fully described by their center point, as the radius can be calculated from the position of the center and the distortion parameter only. This publication collects the properties of this distortion model from several sources and reviews them. Moreover, we show in this publication that the space of this center is projectively isomorphic to the dual space of the undistorted image plane, i.e. its line space. Therefore, projective invariant measurements on the undistorted lines are possible by the according measurements on the centers of the distorted circles. As an example of application, we use this to find the metric distance of two parallel straight rails with known track gauge in a single uncalibrated camera image with significant radial distortion.

scholarly journals A Vision Calibration Method of Robot based on Halcon

2020 ◽  
Vol 14 ◽  
Keyword(s):  
Vision System ◽  
Industrial Robot ◽  
Robot Vision ◽  
Calibration Method ◽  
System Calibration ◽  
Radial Distortion ◽  
Vision Control ◽  
Calibration Accuracy ◽  
The Relationship ◽  
Research Hotspots

Visual calibration is an important researchdirection in the field of robot vision control, and is also one of thecurrent research hotspots. In this paper, the principle of softwarecalibration is described in detail, and a software calibrationmethod based on Halcon optimization is studied and designed. Byusing the operator in the function library, the internal andexternal parameters of the camera are calibrated. The influence ofthe terminal center of the robot and the radial distortion of thecamera lens is fully considered. The method is used to establish thecamera. The relationship between the image coordinated systemand the robot world coordinated system. Experiments show thatthe method has high calibration accuracy and practicability, andis suitable for industrial robot vision system calibration.

Measurement of Cam Spacing on Assembled Camshaft Based on Improved Fundamental Matrix Calibration

2013 ◽  
Vol 850-851 ◽  
pp. 241-244
Author(s):  
Guan Nan Li ◽  
Qing Chang Tan ◽  
Si Yuan Liu
Keyword(s):  
Fundamental Matrix ◽  
Ccd Camera ◽  
Calibration Method ◽  
Measurement Model ◽  
Pinhole Camera ◽  
Epipolar Line ◽  
Camera Model ◽  
Distortion Model ◽  
Imaging Model ◽  
Measurement Results

Imaging model of double CCD camera based on pinhole camera model and distortion model is introduced, and the fundamental matrix is presented. Distortion model is led into the fundamental matrix calibration. Based on the imaging model of Z. Zhangs calibration method, fundamental matrix is carried out. Pixel coordinate for calibration is modified by cameras interior parameters and distortion coefficients. Base on the imaging model of double CCD camera, measurement model for cam spacing is established. Cam spacing is measured by the feature of cam edge. In experiments, accurate pixel coordinates of model plane were used in calibration. The distance between a point and its corresponding epipolar line was estimated as the error. The measurement results show that the accuracy of proposed method satisfied the monitoring requirements of the axial positioning error of the cam piece.

scholarly journals Depth-Dependent High Distortion Lens Calibration

Sensors ◽  
2020 ◽  
Vol 20 (13) ◽  
pp. 3695 ◽  
Author(s):  
Carlos Ricolfe-Viala ◽  
Alicia Esparza
Keyword(s):  
Camera Calibration ◽  
Calibration Method ◽  
Complex Problem ◽  
Lens Distortion ◽  
Lens Model ◽  
Distortion Model ◽  
Calibration Methods ◽  
Depth Dependency ◽  
Division Model

Accurate correction of high distorted images is a very complex problem. Several lens distortion models exist that are adjusted using different techniques. Usually, regardless of the chosen model, a unique distortion model is adjusted to undistort images and the camera-calibration template distance is not considered. Several authors have presented the depth dependency of lens distortion but none of them have treated it with highly distorted images. This paper presents an analysis of the distortion depth dependency in strongly distorted images. The division model that is able to represent high distortion with only one parameter is modified to represent a depth-dependent high distortion lens model. The proposed calibration method obtains more accurate results when compared to existing calibration methods.

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