CALIBRATION OF SMARTPHONE’S REAR DUAL CAMERA SYSTEM

This paper aims to calibrate smartphone’s rear dual camera system which is composed of two lenses, namely; wide-angle lens and telephoto lens. The proposed approach handles large sized images. Calibration was done by capturing 13 photos for a chessboard pattern from different exposure positions. First, photos were captured in dual camera mode. Then, for both wide-angle and telephoto lenses, image coordinates for node points of the chessboard were extracted. Afterwards, intrinsic, extrinsic, and lens distortion parameters for each lens were calculated. In order to enhance the accuracy of the calibration model, a constrained least-squares solution was applied. The applied constraint was that the relative extrinsic parameters of both wide-angle and telephoto lenses were set as constant regardless of the exposure position. Moreover, photos were rectified in order to eliminate the effect of lens distortion. For results evaluation, two oriented photos were chosen to perform a stereo-pair intersection. Then, the node points of the chessboard pattern were used as check points.

Substation Indoor Wheeled Robot Inspection Visual Blind Pressure Plate Recognition

In order to solve the problem of wheeled robots in the main control room of the substation due to the height of the robot and the shooting distance, the main camera cannot take a complete picture of the bottom pressure plate of the relay protection pressure plate cabinet during the inspection process and perform open/close state and label image recognition. Propose install a wide-angle secondary camera on the side of wheeled robot, and targeted proposal for the correction of distorted images taken with a wide-angle lens using a division model, improving the accuracy of decompression plate checks. Experiments have shown that, the proposed approach is practical and feasible, effective solution for indoor wheeled robot relay panel cabinet inspection visual blind spot shooting problem, enhanced the effectiveness of wheeled robotic inspections in the main control room of the substation, improved platen verification accuracy.

Model-Free Lens Distortion Correction Based on Phase Analysis of Fringe-Patterns

The existing lens correction methods deal with the distortion correction by one or more specific image distortion models. However, distortion determination may fail when an unsuitable model is used. So, methods based on the distortion model would have some drawbacks. A model-free lens distortion correction based on the phase analysis of fringe-patterns is proposed in this paper. Firstly, the mathematical relationship of the distortion displacement and the modulated phase of the sinusoidal fringe-pattern are established in theory. By the phase demodulation analysis of the fringe-pattern, the distortion displacement map can be determined point by point for the whole distorted image. So, the image correction is achieved according to the distortion displacement map by a model-free approach. Furthermore, the distortion center, which is important in obtaining an optimal result, is measured by the instantaneous frequency distribution according to the character of distortion automatically. Numerical simulation and experiments performed by a wide-angle lens are carried out to validate the method.

Analysis of futsal matches using a single-camera computer vision system

The use of computer systems in sports has increased significantly in the last decade. Consequently, systems have been developed to help each athlete or team quantify their performance, such as distances traveled, speeds attained, and positions where each athlete was on the court or field. In this work, a method based on computer vision is proposed to analyse futsal matches. Videos were acquired using a single camera with a wide-angle lens, which facilitates the installation and calibration process in different matches and arenas. The approach is illustrated through video recordings of Pato Futsal team, from which the athletes were detected, their positions projected from pixels to real world coordinates their trajectories estimated. The generated data visualization aims to help coaches in their physical and tactical analysis.

Introduction to the Special Issue: Global Perspectives in Sport Management Education

There is no doubt that sport has become a global industry. Therefore, it is crucial that global perspectives be integrated into sport management education, which is no doubt occurring. However, little has been published to date on the impact and effectiveness of curricular strategies aimed at internationalizing sport management education. This special issue provides sport management faculty with thoughtful dialogue on how they can educate their students for what has become an ever-changing global landscape. The articles in this issue capture global perspectives representing the breadth of activity across a burgeoning dimension of sport management education. The authors have used a variety of research designs that, taken together, provide a wide-angle lens on the nature of global sport management education and how effective it can be.