A Flexible Calibration Approach for Cameras with Double-Sided Telecentric Lenses

Yao, Linshen; Liu, Haibo

doi:10.5772/63825

Cited by 26 publications

(8 citation statements)

References 25 publications

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“…In work [28], the planar pattern was moved along the z-direction of the world coordinate with a precision positioning stage, so the extrinsic parameter can be determined by comparing the reprojection with two poses of camera. In contrast, the complete position of the mark points is known in the 3Dpattern method [63], in which the camera parameters can be estimated by a direct linear transformation. For SEMs, both projection models have been used in terms of magnifications [64].…”

Section: B Geometric Models and Calibration Methods Of The Typical Micro-vision Systemsmentioning

confidence: 99%

A Review of Computer Microvision-Based Precision Motion Measurement: Principles, Characteristics, and Applications

Sheng

Pang

et al. 2021

IEEE Trans. Instrum. Meas.

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Micro/nano engineering is an emerging field which enables engineering and scientific discoveries in the microworld. As an effective and powerful tool for automation and manipulation at small scales, precision motion measurement by computer micro-vision is now broadly accepted and widely used in micro/nano engineering. Unlike other measurement methods, the vision-based techniques can intuitively visualize the measuring process with high interactivity, expansibility, and flexibility. This review paper aims to comprehensively present a survey of micro-vision-based motion measurement from the collective experience. Working principles of micro-vision systems are firstly introduced and described, where the hardware configuration, model calibration, and motion measurement algorithms are systematically summarized. The characteristics and performances of different micro-vision-based methods are then analyzed and discussed in terms of measurement resolution, range, degree of freedom, efficiency, and error sources. Recent advances of applications empowered by the developed computer micro-visionbased methods are also presented. The review can be helpful to researchers who engage in the development of micro-vision-based techniques, as well as provide the recent state and tendency for the research community of vision-based measurement, manipulation, and automation at micro/nano scales.

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Section: B Geometric Models and Calibration Methods Of The Typical Micro-vision Systemsmentioning

confidence: 99%

A Review of Computer Microvision-Based Precision Motion Measurement: Principles, Characteristics, and Applications

Sheng

Pang

et al. 2021

IEEE Trans. Instrum. Meas.

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“…]. " Yao and Liu 21 introduced an approach where again an additional stage is used to solve for the extrinsic sign ambiguity. After a camera start value determination based on a distortion-free camera model, two nonlinear optimization steps are executed.…”

Section: Planar-object-based Methodsmentioning

confidence: 99%

“…As no metric distances are defined on the 3-D calibration target, the authors suggest the additional usage of a simple 2-D target in a planebased calibration routine, such as given in Ref. 21. In the second step, the initial guesses are used as start parameters in a nonlinear bundle adjustment scheme to minimize the total projection error.…”

Section: Hybrid Methodsmentioning

confidence: 99%

Calibration routine for a telecentric stereo vision system considering affine mirror ambiguity

et al. 2020

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A robust calibration approach for a telecentric stereo camera system for threedimensional (3-D) surface measurements is presented, considering the effect of affine mirror ambiguity. By optimizing the parameters of a rigid body transformation between two marker planes and transforming the two-dimensional (2-D) data into one coordinate frame, a 3-D calibration object is obtained, avoiding high manufacturing costs. Based on the recent contributions in the literature, the calibration routine consists of an initial parameter estimation by affine reconstruction to provide good start values for a subsequent nonlinear stereo refinement based on a Levenberg-Marquardt optimization. To this end, the coordinates of the calibration target are reconstructed in 3-D using the Tomasi-Kanade factorization algorithm for affine cameras with Euclidean upgrade. The reconstructed result is not properly scaled and not unique due to affine ambiguity. In order to correct the erroneous scaling, the similarity transformation between one of the 2-D calibration plane points and the corresponding 3-D points is estimated. The resulting scaling factor is used to rescale the 3-D point data, which then allows in combination with the 2-D calibration plane data for a determination of the start values for the subsequent nonlinear stereo refinement. As the rigid body transformation between the 2-D calibration planes is also obtained, a possible affine mirror ambiguity in the affine reconstruction result can be robustly corrected. The calibration routine is validated by an experimental calibration and various plausibility tests. Due to the usage of a calibration object with metric information, the determined camera projection matrices allow for a triangulation of correctly scaled metric 3-D points without the need for an individual camera magnification determination.

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“…Then, the target was moved a known distance along its normal vector. The images before and after movement were captured and subsequently used for unambiguously determining the rotation matrix [9][10][11][12][13][14]. However, these methods are inflexible because of the use of the extra translation stage device.…”

Section: Introductionmentioning

confidence: 99%

Telecentric camera calibration with virtual patterns

Chen¹,

Чэн²,

Pan³

2021

Meas. Sci. Technol.

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We propose an easy-to-implement and automatic telecentric camera calibration method. The proposed method adopts a virtual planar target, which is actively transformed and displayed on a fixed liquid crystal display screen, for calibrating telecentric cameras. Compared with regular methods that require human interaction to move physical planar targets, the proposed method offers the merits of simple and automatic calibration implementation, since it eliminates the needs of manufacturing and manually moving a physical calibration target. For validation, a single-camera telecentric pseudo-stereo vision system was calibrated using the proposed method. The calibrated telecentric stereo vision system was further used for three-dimensional reconstruction of both planar and complex surfaces. Experimental results demonstrate the proposed calibration method can be used for accurate telecentric stereo vision measurement.

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A Flexible Calibration Approach for Cameras with Double-Sided Telecentric Lenses

Cited by 26 publications

References 25 publications

A Review of Computer Microvision-Based Precision Motion Measurement: Principles, Characteristics, and Applications

A Review of Computer Microvision-Based Precision Motion Measurement: Principles, Characteristics, and Applications

Calibration routine for a telecentric stereo vision system considering affine mirror ambiguity

Telecentric camera calibration with virtual patterns

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