Camera Calibration for 3D Reconstruction and View Transformation

2011 ◽  
pp. 70-129
Author(s):  
B. J. Lei ◽  
E. A. Hendriks ◽  
Aggelos K. Katsaggelos
Keyword(s):  
3D Reconstruction ◽  
Camera Calibration ◽  
Mathematical Description ◽  
The Self ◽  
Model Reconstruction ◽  
Face Model ◽  
Self Calibration ◽  
Calibration Methods ◽  
View Transformation ◽  
Calibration Techniques

This chapter presents an extensive overview of passive camera calibration techniques. Starting with a detailed introduction and mathematical description of the imaging process of an off-the-shelf camera, it reviews all existing passive calibration approaches with increasing complexity. All algorithms are presented in detail so that they are directly applicable. For completeness, a brief counting about the self-calibration is also provided. In addition, two typical applications are given of passive camera calibration methods for specific problems of face model reconstruction and telepresence and experimentally evaluated. It is expected that this chapter can serve as a standard reference. Researchers in various fields in which passive camera calibration is actively or potentially of interest can use this chapter to identify the appropriate techniques suitable for their applications.

Parallel Robot Calibration Utilizing Adaptronic Joints

2008 ◽  
Author(s):  
Philipp Last ◽  
Annika Raatz ◽  
Ju¨rgen Hesselbach ◽  
Nenad Pavlovic ◽  
Ralf Keimer
Keyword(s):  
Parallel Robot ◽  
Parallel Robots ◽  
Machine Component ◽  
Robot Calibration ◽  
Geometric Calibration ◽  
Self Calibration ◽  
Mechanical Constraints ◽  
Special Machine ◽  
Calibration Methods ◽  
Calibration Techniques

Model based geometric calibration is well known to be an efficient way to enhance absolute accuracy of robotic systems. Generally its application requires redundant measurements, which are achieved by external metrology equipment in most traditional calibration techniques. However, these methods are usually time-consuming, expensive and inconvenient. Thus, so-called self-calibration methods have achieved attention from researchers, which either use internal sensors or rely on mechanical constraints instead. In this paper a new self-calibration technique is presented for parallel robots which is motivated by the idea of constrained calibration. The new approach utilizes a special machine component called the adaptronic swivel joint in order to achieve the required redundant information. Compared to similar approaches it offers several advantages. The new calibration scheme is described and verified in simulation studies using a RRRRR-structure as an example.

scholarly journals Obstacle-based self-calibration techniques for the determination of the permittivity of liquids

2007 ◽  
Vol 5 ◽  
pp. 29-35 ◽  
Author(s):  
I. Rolfes
Keyword(s):  
Industrial Process ◽  
Calibration Procedure ◽  
Microwave Frequencies ◽  
Material Parameters ◽  
Self Calibration ◽  
Calibration Methods ◽  
Measurement Cell ◽  
Calibration Techniques ◽  
Transmission And Reflection

Abstract. In this contribution, different obstacle-based self-calibration techniques for the measurement of the dielectric properties of liquids are investigated at microwave frequencies. The liquid under test is contained inside a waveguide, which is connected to the ports of a vector network analyzer. The permittivity of the liquid is characterized on the basis of the measured scattering parameters. In order to extract the material parameters precisely and to eliminate systematic errors of the setup, calibration measurements have to be performed. For this purpose, different self-calibration methods based on the displacement of an obstacle are considered. The presented methods differ in that way, that either transmission and reflection measurements or purely reflection measurements are performed. All these methods have in common that the material parameters are already calculable within a so-called self-calibration procedure. Thus, a full two-port calibration of the whole setup is not necessary. Furthermore, the methods can be realized effectively in a practical setup having the advantage that a rearrangement of the setup is not needed for the material parameter measurements and that the liquid under investigation can pass continuously through the measurement cell. This might be of interest for the application in an industrial process, enabling the continuous flow of the material while the parameter characterization can take place at the same time.

TOWARDS THE SELF-CALIBRATION OF A MULTIVIEW RADIOGRAPHIC IMAGING SYSTEM FOR THE 3D RECONSTRUCTION OF THE HUMAN SPINE AND RIB CAGE

1999 ◽  
Vol 13 (05) ◽  
pp. 761-779 ◽  
Author(s):  
F. CHERIET ◽  
J. DANSEREAU ◽  
Y. PETIT ◽  
C.-É. AUBIN ◽  
H. LABELLE ◽  
...  
Keyword(s):  
3D Reconstruction ◽  
Coordinate System ◽  
Imaging System ◽  
The Self ◽  
Reference Plane ◽  
Global Coordinate System ◽  
Optimal Estimate ◽  
Rib Cage ◽  
Human Spine ◽  
Self Calibration

The main objective of this study was to develop a 3D reconstruction technique of the spine and rib cage of idiopathic scoliotic patients using the self-calibration of the imaging system. The proposed approach computes the intrinsic and extrinsic parameters of the radiographic setup with respect to the global coordinate system used at Ste-Justine Hospital. Our approach determines an optimal estimate of the geometrical parameters of the imaging system from a nonlinear minimization of the mean square distance between the observed and analytical projections of a set of matched points identified on a pair of radiographic views. The accuracy of the optimal estimate for the intrinsic parameters was significantly improved when geometric knowledge such as the known length of detectable straight bars is incorporated as a set of equality constraints in the optimization process. Furthermore, in order to retrieve the 3D structure of interest in the global coordinate system, a reference plane including the origin of the global coordinate system is specified. Computer simulations were performed to evaluate the self-calibration procedure and to determine the minimum knowledge required to obtain an accurate 3D reconstruction for clinical applications. An in vitro validation on real images of a dry cadaveric human spine showed that the method is feasible and reaches the expected accuracy.

An Enhanced On-Line Service for 3D Model Construction from Photographs

2012 ◽  
Vol 1 (2) ◽  
pp. 277-294 ◽  
Author(s):  
David Tingdahl ◽  
Gool Van Luc
Keyword(s):  
3D Reconstruction ◽  
Web Service ◽  
Camera Calibration ◽  
3D Model ◽  
Digital Camera ◽  
Calibration Method ◽  
Complete Model ◽  
On Line ◽  
Automatic Camera Calibration ◽  
Calibration Techniques

We present a web service for image based 3D reconstruction. The system allows a cultural heritage professional to easily create a 3D model of a scene or object out of images taken from different viewpoints. The user uploads the images to our server on which all processing takes place, and the final result can be downloaded upon completion. Any consumer-class digital camera can be used, and the system is free to use for non-commercial purposes. The service includes a number of innovations to greatly simplify the process of taking pictures suitable for reconstruction. In particular, we are able to construct models of planar scenes and from photographs shot using a turntable, and at varying zoom levels. Although the first two may seem like particularly simple cases, they cause some mathematical issues with traditional self-calibration techniques. We handle these cases by taking advantage of a new automatic camera calibration method that uses meta-data stored with the images. For fixed-lens camera setups, we can also reuse previously computed calibrations to support otherwise degenerate scenes. Furthermore, we can automatically compute the relative scale and transformation between two reconstructions of the same scene, merging two reconstructions into one. We demonstrate the capabilities of the system by two case studies: turntable reconstruction of various objects and the reconstruction of a cave, with walls and roof integrated into a complete model.

scholarly journals A Multi Camera and Multi Laser Calibration Method for 3D Reconstruction of Revolution Parts

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 765
Author(s):  
Hugo Álvarez ◽  
Marcos Alonso ◽  
Jairo R. Sánchez ◽  
Alberto Izaguirre
Keyword(s):  
3D Reconstruction ◽  
Calibration Method ◽  
Laser Plane ◽  
Calibration Methods ◽  
Laser Calibration ◽  
Calibration Object ◽  
Focus Plane ◽  
Chessboard Pattern ◽  
Line Patterns

This paper describes a method for calibrating multi camera and multi laser 3D triangulation systems, particularly for those using Scheimpflug adapters. Under this configuration, the focus plane of the camera is located at the laser plane, making it difficult to use traditional calibration methods, such as chessboard pattern-based strategies. Our method uses a conical calibration object whose intersections with the laser planes generate stepped line patterns that can be used to calculate the camera-laser homographies. The calibration object has been designed to calibrate scanners for revolving surfaces, but it can be easily extended to linear setups. The experiments carried out show that the proposed system has a precision of 0.1 mm.

scholarly journals Extrinsic Parameters Calibration Method of Cameras with Non-Overlapping Fields of View in Airborne Remote Sensing

2018 ◽  
Vol 10 (8) ◽  
pp. 1298 ◽  
Author(s):  
Lei Yin ◽  
Xiangjun Wang ◽  
Yubo Ni ◽  
Kai Zhou ◽  
Jilong Zhang
Keyword(s):  
Remote Sensing ◽  
Camera Calibration ◽  
Calibration Method ◽  
Optimization Method ◽  
Airborne Remote Sensing ◽  
Camera System ◽  
Translation Error ◽  
Camera Systems ◽  
Calibration Methods ◽  
Extrinsic Parameters

Multi-camera systems are widely used in the fields of airborne remote sensing and unmanned aerial vehicle imaging. The measurement precision of these systems depends on the accuracy of the extrinsic parameters. Therefore, it is important to accurately calibrate the extrinsic parameters between the onboard cameras. Unlike conventional multi-camera calibration methods with a common field of view (FOV), multi-camera calibration without overlapping FOVs has certain difficulties. In this paper, we propose a calibration method for a multi-camera system without common FOVs, which is used on aero photogrammetry. First, the extrinsic parameters of any two cameras in a multi-camera system is calibrated, and the extrinsic matrix is optimized by the re-projection error. Then, the extrinsic parameters of each camera are unified to the system reference coordinate system by using the global optimization method. A simulation experiment and a physical verification experiment are designed for the theoretical arithmetic. The experimental results show that this method is operable. The rotation error angle of the camera’s extrinsic parameters is less than 0.001rad and the translation error is less than 0.08 mm.

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