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A New Method of Recognizing Polygons under perspective transformation

Computer Aided Drafting,Design and Manufacturing 2007年第1期17卷 80-85页

作者： ZHANG Gui-mei GAO Man-tun SHEN Yun-wen Key Laboratory of Nondestructive Test Nanchang Institute of Aeronautical Technology Nanchang 330063 China Institute of Mechanical and Electrical Engineering Northwestern Polytechnical University Xi＇an 710072 China

Existing methods for recognizing polygons can be improved. A new concept ＂homograph＂ and then a new method for recognizing polygons based on the principle of homograph are proposed. First, five topological characteristics and geometrical characteristics are introduced that are invariant to describe polygon under perspective transformation. Then, the new concept of homograph is defined in terms of five topological characteristics and geometrical characteristics. Based on this definition, a new algorithm is proposed for recognizing that two polygons are homograph. The topological structure is introduced to analyze homograph qualitatively and the algorithm is insensitive to noises; and the geometrical structure is introduced to analyze homograph quantitatively, thus the algorithms can show tiny differences between polygons. It can not only recognize the objects with different shapes but also distinguish between objects with same shape but with different sizes and scales. Comparing with other recognition algorithms, the algorithm presented showed apparent improvement. The effectiveness of the algorithm is demonstrated by experiments.

关键词： perspective transformation polygon homograph recognition

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Critical Technical Awakenings

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Journal of Social Computing 2021年第4期2卷 365-384页

作者： Maya Malik Momin M.Malik the School of Social Work McGill UniversityMontréalH3A 0G4Canada the Institute in Critical Quantitative Computational&Mixed MethodologiesJohns Hopkins UniversityBaltimoreMD 21218USA

Starting with Philip ***’s 1997 essay on“critical technical practice”,we consider examples of writings from computer science where authors describe“waking up”from a previously narrow technical approach to the world,enabling them to recognize how their previous efforts towards social change had been *** use these examples first to talk about the underlying assumptions of a technology-centric approach to social problems,and second to theorize these awakenings in terms of Paulo Freire’s idea of critical ***,understanding these awakenings among technical practitioners as examples of this more general phenomenon gives guidance for how we might encourage and guide critical awakenings in order to get more technologists working effectively towards positive social change.

关键词： critical technical practice critical consciousness perspective transformation education machine learning

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自动驾驶视觉感知中基于对称分子边缘检测的鲁棒车道线检测技术

自动驾驶视觉感知中基于对称分子边缘检测的鲁棒车道线检测技术

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作者： Amma Hazel Kargbo 浙江理工大学

学位级别：硕士

Road lane detection is a fundamental component of the vision-based selfdriving automobile *** serves as a basis for more advanced course planning and control operations such as braking and *** feature-based lane identification,the results of lane edge detection are *** edges left by tough conditions（illumination and shadows）in the form of noise on roadways interfere with accurate lane line detection,providing a severe *** work proposes an improved algorithm to take advantage of edge orientations for robust lane detection based on edge detection with symmetric molecules,which exploits the symmetric properties of directionally sensitive analytical functions in multi-scale systems,adaptive HSI colour model,perspective transformations,and histogram *** final approach may be used to identify straight and curved lane *** simulation results from various scenarios are shown to show how the proposed lane identifying approach outperforms previous methods.

关键词： Lane Detection perspective transformation Self-driving cars Robotic Vision HSI colour model

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A Distance Measurement Method Based on Dual-parallel-line Projection for A Non-parameter Shooting System

A Distance Measurement Method Based on Dual-parallel-line Pr...

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第三十九届中国控制会议

作者： Chen Du Jinhua She Xu Jian Mengxi Qin School of Automation China University of Geosciences Hubei Key Laboratory of Advanced Control and Intelligent Automation for Complex Systems School of Engineering Tokyo University of Technology

Most images or videos are taken using mobile phones or other daily necessities. Unlike a professional device, those ready-to-use everyday items do not have a binocular or multi-ocular visual system. Thus, it is almost impossible to obtain the whole set of the internal parameters(the characteristics of a device, for example, a focal length) and the external parameters(the coordinates and rotational angles of a world coordinate system). For this reason, how to extract a distance is a difficult task and only few methods have been proposed to solve this problem. This paper presents a dual-parallel-line projection model to simply calculate the distance of a straight line for a target in a image. The model does not require any internal or external parameters and only needs very limited geometric information of an image. An image is processed using only a monocular vision system and an image perspective transformation. First, a monocular vision model is established to extract mathematical relationships between a photographer, target points, and target straight lines in a image. Then, a perspective transformation is carried out to change the angle of view on the plane to an angle of depression. An object with known length in the figure is calibrated to calculate the length of a target on the plane. Finally, auxiliary lines related to an object with known geometric information are added to the orignal image, and the results of the perspective transformation for those lines are claculated. The geometrical distance of a straight line between the photographer and the target is calculated using the mathematical relationship of the monocular vision model. Examples illustrate the validity of the method.

关键词： Monocular Vision System perspective transformation Model Calibration 3D Measurement

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People Flow Monitoring Based on Deep Learning

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国际计算机前沿大会会议论文集 2023年第2期 153-167页

作者： Xinran Wang Yanqing Wang Yiqing Xu Tianxin Wang Nanjing Xiaozhuang University NanjingChina

According to the application scenarios of the size of the humanﬂow in different consumption places,to solve the problem of crowd detection,distance estimation between crowds and the inability to monitor and calculate the humanﬂow in real time,this paper designs a real-time crowd detection scheme for appli-cation scenarios where consumers pay attention to the size of the humanﬂow in consumption *** main use of the YOLO algorithm with the Darknet53 net-work as the main network is to separate pedestrians from the ***-trians’central two-dimensional coordinates are converted into three-dimensional coordinates,realizing crowd detection and apart from the distance estimation of crowds,real-time monitoring of current regional trafﬁc andﬂow density,and solv-ing the problem of being unable to monitor and calculate people in real *** can be applied to many aspects,such as shop rating,trafﬁc control andﬂow control of scenic *** monitors are affected by different lights and cannot provide accurate *** addition,the processing algorithm of this scheme is stable and accurate,and preprocessing is performed before judging the humanﬂow and the position of the human body to reduce the interference of *** scheme has the performance of real-time monitoring and calculation through experimental veriﬁcation.

关键词： Target detection perspective transformation Distance detection Population density

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Research on Image Navigation Algorithms for UAV

Research on Image Navigation Algorithms for UAV

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作者： Bai ZHANG Cai-ying WEI Rui-ting GE School of Electrical Information Engineering North Minzu University

UAV（unmanned aerial vehicle） is used in agriculture filed to inspect water conservancy facilities, it not only can greatly reduce labor, but also effectively save relevant costs. The choice of UAV navigation mode is the key problem to achieve patrol of water conservancy facilities. In order to solve this problem, a new method of UAV image navigation is proposed which is different from traditional image navigation, and experimental research is carried out. Firstly, the acquired image is corrected and preprocessed to reduce image noise by perspective transformation. Then, the target information is extracted by threshold segmentation and ROI（region of interest） method. Finally, the attitude information of UAV is calculated and displayed in the original image through OpenCV（Open Source Computer Vision Library） library function. Based on the calculation results, the attitude of UAV can be adjusted by flight controller.

关键词： perspective transformation Threshold segmentation ROI OpenCV

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