CCD Camera Calibration Research Articles

Geometric calibration of domestic airborne wide-field three-linear CCD camera

Geometric calibration of domestic airborne wide-field three-linear CCD camera

Design of multi-parameter target used in calibration of high precision CCD camera

In order to achieve some performance requirements of high location accuracy, real-time dynamic variation and target brightness change that existing conventional calibration method could not realize the calibration of high precision CCD camera, a design of high precision multi-parameter target based on the fiber light technology and the fiber coupling technology between fiber and surface light source is proposed, which innovatively applies to fiber coupling mechanism based on OLED face light source and high precision target plate to simulate the standard targets for CCD camera's calibration. Firstly, to determine the work parameters of selected OLED, the factors of optical coupling between fiber and face light source are analyzed based on the basic indicator of simulated target's brightness. By studying the size of the glowing target, the choice of optical fiber parameters is determined. At last, through analyzing transmission properties of the light energy and the brightness control technology of the OLED light face, we determine standard simulation models of six different brightness. The actual test results also show that the proposed method is correct and feasible and can guarantee the technical requirements for the high precision CCD camera's calibration.

Line-scan CCD camera calibration in 2D coordinate measurement

We present a line-scan camera calibration method in a plane not perpendicular to but parallel to the optical axis, without requiring the camera motion or a complex calibration pattern. A random 2D reference coordinate system in the calibration plane can be used, images of a rod perpendicular to the calibration plane at known coordinates are captured by the camera, the relation between the given coordinates and the rod image centroid position are analyzed based on a reduced pinhole model and image processing, and then the camera parameters and distortion factors are all estimated. These distortion factors build a sample relation only between the image position in theory and in practice, and they do not change with object position. Two wide-angle line-scan cameras that are used in a 2D-coordinate measurement system are calibrated by this method; the application results illustrate the effectiveness and convenience of this method.

CCD Camera Calibration Technology Based on the Translation of Coordinate Measuring Machine

A new CCD camera calibration method based on the translation of Coordinate Measuring Machine (CMM) is proposed. The CMM brings the CCD camera to produce the relative translation with respect to the center of the white ceramic standard sphere along the X, Y, Z axis, and the coordinates of the different positions of the calibration characteristic point in the probe coordinate system can be generated. Meanwhile, the camera captures the image of the white ceramic standard sphere at every position, and the coordinates of the calibration characteristic point in the computer frame coordinate system can be registered. The calibration mathematic model was established, and the calibration steps were given and the calibration system was set up. The comparing calibration result shows that precision of this method is equivalent to that of the special calibration method, and the difference between the calibrating data of these two methods is within ±1μm.

Design of Calibration System for a Great Quantity of High Precision Scientific Grade CCD Cameras

For the calibration of a great quantity of scientific grade CCD cameras in the high energy physics system, a scientific grade CCD camera calibration system with high precision and efficiency is designed. The designed camera calibration system consists of a 1053nm nanosecond solid-state laser, a knife, a double-integrating sphere, a laser power meter, a signal generator, a computer with its data processing software. Key technical parameters of scientific grade CCD under the condition of 1053nm optical pulses that are the modulation, contrast, defects, optical dynamic range, non-linear response can be calibrated by the designed calibration system. A double-integrating sphere with high uniformity and stability is designed as a uniform light source, which improves the calibrating performance and accuracy. Experimental results show the system designed in this paper can calibrate the large number of scientific grade CCD cameras quickly and efficiently.

Application of Detecting Part's Size Online Based on Machine Vision

In order to use a method untouched to measure part's size, detection system is built. The research is on characteristic point detection, CCD camera calibration and distance detection between two special points. Firstly, the theory of edge detection based on Gauss point spread function is introduced. Secondly, it is calibrated using the characteristic points on the edge. Then a simple CCD calibration method of resolving the solution is deduced to solve the related parameters of model. Finally, 3D special coordinates of characteristic points detected can be obtained by the model. It is realized to detecting part size process online by calculating the distance between two special points. The experimental result shows that when physical length is 0.6 times than focal length, the given precise of measuring result can reach nearly 0.006mm. The precise of image is stable.

基于衍射光栅的CCD相机标定方法

基于衍射光栅的CCD相机标定方法

Novel Calibration and Lens Distortion Correction of 3D Reconstruction Systems

A novel calibration and lens distortion correction of 3D reconstruction systems is introduced in this paper. Assuming zero distortion at the center of image, the parameter calibration and lens distortion correction of CCD camera and DLP projector is separated with the points in center and all the rest points. Furthermore, identification and correspondence of the interest points is done automatically because of the designed target with standard circles and multicolor code of pseudo-random array during the calibration. The experiments show that it is a fast and convenient method to carry out the calibration for lens distortion.

Design and Implementation of 4S-Van: A Mobile Mapping System

Recent advances in positioning and photogrammetry technologies have made it possible to build a mobile mapping system (MMS) that can obtain 3D coordinates of geographic objects from stereo images recorded from a moving vehicle. In this paper, we present a design and detailed implementation of an MMS called a 4S-Van. Furthermore, we present four issues that have made major contributions to the performance of an MMS: 1) CCD camera calibration, 2) GPS signal condition, 3) integrating a GPS, inertial navigation system (INS), distance measurement indicator (DMI), and CCD cameras, and 4) the orientation angle of CCD cameras. In the experimental results, the performance of an MMS was analyzed for each component, giving an idea of how to effectively design and integrate each component in developing an MMS to get a maximal accuracy of 3D coordinates.

A flexible new three-dimensional measurement technique by projected fringe pattern

Aimed at the problems of inferior precision and bad maneuverability for three-dimensional (3D) measurement by projected fringe pattern, a flexible new 3D technique for performing system calibration and measuring was proposed. First, we analyzed the principle of conventional 3D measurement with projected fringe pattern, and pointed out the shortcoming of measurement system. Then, the CCD camera calibration technique is analyzed and we set up the perspective projection model which transforms the computer image coordinate to 3D world coordinate, and we get the coordinate of the CCD camera image lens. Third, the position of projection lens optical center can be obtained using the above model. At last, some experiment results presented show that this technique is more simple and robust in engineering than conventional measurement method.

Effects of point-spread function on calibration and radiometric accuracy of CCD camera.

The point-spread function (PSF) of a camera can seriously affect the accuracy of radiometric calibration and measurement. We found that the PSF can produce a 3.7% difference between the apparent measured radiance of two plaques of different sizes with the same illumination. This difference can be removed by deconvolution with the measured PSF. To determine the PSF, many images of a collimated beam from a He-Ne laser are averaged. Since our optical system is focused at infinity, it should focus this source to a single pixel. Although the measured PSF is very sharp, dropping 4 and 6 orders of magnitude and 8 and 100 pixels away from the point source, respectively, we show that the effect of the PSF as far as 100 pixels away cannot be ignored without introducing an appreciable error to the calibration. We believe that the PSF should be taken into account in all optical systems to obtain accurate radiometric measurements.

Bundle adjustments CCD camera calibration based on collinearity equation

Bundle adjustments CCD camera calibration based on collinearity equation

Retrieval of spatial shot-noise in the full dynamic range of calibrated CCD cameras

The pixel by pixel calibration of a scientific CCD camera allows Poissonian statistics of the spatial fluctuations of an uniform enlightening to be retrieved in the full range of the camera dynamic. The procedure works efficiently for thermal as well as for laser sources, provided that the wavelength and the coherence properties of the source are chosen in order to avoid the formation of equal thickness fringes in the chip (etaloning effect). Calibration allows also the comparison at the shot noise level of images recorded at different places on the chip.

Stereo Vision-Based Robot Servoing Control for Object Grasping.

In this paper, a stereo vision-based robot servoing control approach is presented for object grasping. Firstly, three-dimensional projective reconstruction with two free-standing CCD cameras and homogeneous transformation are used to specify the goal grasping position and orientation of a robot hand. Secondly, a stereo vision-based servoing problem is formulated, and a stereo vision-based servoing control algorithm which is independent of robotic dynamics is proposed. Using this algorithm, a set of velocity reference inputs can be obtained to control the motions and velocities of the robot hand during the visual servoing. Thirdly, the methods for coping with the time delay of image processing and the CCD camera calibration are put forward. Lastly, the effectiveness of the present approach is verified by carrying out several experiments on object grasping using a 6 degrees of freedom robot. Its stability and robustness as well as flexibility are also confirmed by the experimental results.

HIGH PRECISION CCD CALIBRATION AND ITS APPLICATIONS

ABSTRACT With the help of CCD images, the realization of high precision positioning and measurement has become the basic standard for machine vision and real time photogrammetry systems. However, deformation and other sorts of degradation occurring during transmission are major limiting factors of the precision attainable with most current CCD cameras and frame grabbers. So a precise radiometric and geometric transmission of images from CCD sensor to memory is a fundamental aspect of CCD camera calibration. The geometric calibration system, which uses some image processing algorithms of the CCD camera based on the researched and developed system is discussed. The reliability and validity are also discussed. The experimental results for the calibration of the CCD array will be taken as an important quality index for CCD evaluation.

Concepts of real-time photogrammetry

The paper briefly outlines the concepts of digital photogrammetry under special consideration of real-time aspects, including subpixel accuracy measurements in image space, techniques for the robust establishment of multi-image correspondences, strict geometric modeling for 3-D coordinate determination, CCD camera calibration issues and possibilities of statistical data analysis.

リアルタイムフォトグラメトリのためのＣＣＤカメラキャリブレーション

リアルタイムフォトグラメトリのためのＣＣＤカメラキャリブレーション

Linejitter and geometric calibration of CCD-cameras

Precise radiometric and geometric transmission of images from CCD-sensor to memory is a fundamental aspect of CCD-camera calibration. Linejitter and other degradation occurring during transmission are major limiting factors of the precision attainable with most current CCD-cameras and framegrabbers. The video signal, synchronisation signals and principal electronic components involved in synchronisation and transmission are analysed and their influence on linejitter discussed. A method for signal transmission with the elimination of linejitter and other degradations is shown. Methods for the determination and correction of linejitter are discussed.

Ground-Based Photometric Calibration of the Space Telescope CCD Camera

The Wide-Field and Planetary Camera (WF/PC) is a CCD imaging instrument which is part of the Hubble Space Telescope. Ground-based observations have been made with a CCD system similar to those of the WF/PC in order to establish the standard star sequence to be used for in-flight photometric calibration. Because the WF/PC passbands differ from those in previous photometric use, the filters and CCDs will define a new photometric system. We outline here the procedures used to establish the calibration fields to be used in flight (see Harris et al. 1988 for additional details).