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GRADIENT OF REFERENCE DIFFERENCE BASED MATCHING ALGORITHM FOR IMAGE feature point

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Journal of Electronics(China) 2004年第2期21卷 163-169页

作者： GuanYepeng GuWeikang YeXiuqing LiuJilin DeptofInformationScienceandElectron.Eng. ZhejiangUniversityHangzhou310027

During matching on feature point, gray correlation matching technology is utilized to extract multi-peaks as a coarse matching set. A pair of given corresponding reference points within the left and right images is used to calculate gradients of reference difference between the reference points and each feature point within the multi-peaks set. The unique correspondence is determined by criterion of minimal gradients of reference difference. The obtained correspondence is taken as a new pair of reference points to update the reference points continuously until all feature points in the left (or right) image being matched with the right (or left) image. The gradients of reference difference can be calculated easily by means of pre-setting a pair of obvious feature points in the left and right images as a pair of corresponding reference points. Besides, the efficiency of matching can be improved greatly by taking the obtained matching point as a new pair of reference points, and by updating the reference point continuously. It is proved that the proposed algorithm is valid and reliable by 3D reconstruction on two pairs of actual natural images with abundant and weak texture, respectively.

关键词： feature point Gray correlation Multi-peaks set Matching Reference point

Monocular vision-based iterative pose estimation algorithm from corresponding feature points

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Science China(Information Sciences) 2010年第8期53卷 1682-1696页

作者： ZHANG ShiJie 1 , CAO XiBin 1 , ZHANG Fan 1 & HE Liang 2 1 Research Center of Satellite Technology, Harbin Institute of Technology, Harbin 150080, China 2 Shanghai Aerospace Control Engineering Institute, Shanghai 200233, China 1. Research Center of Satellite Technology Harbin Institute of Technology Harbin 150080 China2. Shanghai Aerospace Control Engineering Institute Shanghai 200233 China

To determine the relative pose between an object and a single camera using 2D-to-3D point correspondences, a kind of iterative methods based on inverse projection ray approach is proposed. An iterative algorithm which is divided into depth recovery stage and absolute orientation stage is also proposed. In the first stage, the optimal translation vector is first computed in terms of rotation matrix via least square method, then the depths of the observed points are estimated by projecting the estimated point orthogonally to the inverse projection ray defined by the image point, and finally 3D points are reconstructed using the estimated depths from previous step. In the second stage, the optimal rotation matrix is estimated by applying Umeyama algorithm to fitting of the 3D model points and 3D estimated points. The above two stages are repeated until the result converges. The global convergence of the two-stage iterative algorithm is proven based on the global convergence theorem. Finally, a spacecraft docking application is implemented to test the effectiveness and convergence of the proposed algorithm by mathematical simulation and physical simulation.

关键词： monocular vision feature point relative pose two-stage iterative algorithm global convergence

Geometrically invariant color image watermarking scheme using feature points

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Science in China(Series F) 2009年第9期52卷 1605-1616页

作者： WANG XiangYang MENG Lan YANG HongYing School of Computer and Information Technology Liaoning Normal University Dalian 116029 China State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Beijing 100876 China

Geometric distortion is known as one of the most difficult attacks to resist. Geometric distortion desynchronizes the location of the watermark and hence causes incorrect watermark detection. In this paper, we propose a geometrically invariant digital watermarking method for color images. In order to synchronize the location for watermark insertion and detection, we use a multi-scale Harris-Laplace detector, by which feature points of a color image can be extracted that are invariant to geometric distortions. Then, the self-adaptive local image region （LIR） detection based on the feature scale theory was considered for watermarking. At each local image region, the watermark is embedded after image normalization. By binding digital watermark with invariant image regions, resilience against geometric distortion can be readily obtained. Our method belongs to the category of blind watermarking techniques, because we do not need the original image during detection. Experimental results show that the proposed color image watermarking is not only invisible and robust against common signal processing such as sharpening, noise adding, and JPEG compression, but also robust against the geometric distortions such as rotation, translation, scaling, row or column removal, shearing, and local random bend.

关键词： image watermarking geometric distortion color image feature point image normalization

Image Relaxation Matching Based on feature points for DSM Generation

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Geo-Spatial Information Science 2004年第4期7卷 243-248页

作者： ZHENGShunyi ZHANGZuxun ZHANGJianqing SchoolofRemoteSensingandInformationEngineering 129LuoyuRoadWuhanUniversityWuhan430079China. 不详

In photogrammetry and remote sensing, image matching is a basic and crucial process for automatic DEM generation. In this paper we presented a image relaxation matching method based on feature points. This method can be considered as an extention of regular grid point based matching. It avoids the shortcome of grid point based matching. For example, with this method, we can avoid low or even no texture area where errors frequently appear in cross correlaton matching. In the mean while, it makes full use of some mature techniques such as probability relaxation, image pyramid and the like which have already been successfully used in grid point matching process. Application of the technique to DEM generaton in different regions proved that it is more reasonable and reliable.

关键词： image matching probability relaxation feature point digital surface model

STATISTICAL PROBABILITY BASED ALGORITHM FOR EXTRACTING feature pointS IN 2-DIMENSIONAL IMAGE

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Journal of Electronics(China) 2004年第2期21卷 170-176页

作者： GuanYepeng GuWeikang YeXiuqing LiuJilin DeptofInformationScienceandElectronicsEngineering ZhejiangUniversityHangzhou310027

An algorithm for automatically extracting feature points is developed after the area of feature points in 2-dimensional (2D) imagebeing located by probability theory, correlated methods and criterion for abnormity. feature points in 2D image can be extracted only by calculating standard deviation of gray within sampled pixels area in our approach statically. While extracting feature points, the limitation to confirm threshold by tentative method according to some a priori information on processing image can be avoided. It is proved that the proposed algorithm is valid and reliable by extracting feature points on actual natural images with abundant and weak texture, including multi-object with complex background, respectively. It can meet the demand of extracting feature points of 2D image automatically in machine vision system.

关键词： Probability theory Standard deviation Abnormity Noise feature point

Arm-Root Curve Fitting Based on Body Surface feature points for Young Male

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World Journal of Engineering and Technology 2021年第2期9卷 241-249页

作者： Kaili Liu Hongshu Jin Wuhan Textile University Wuhan Hubei China

This paper is aiming to obtain an arm-root curve function performing the human arm-root size and shape realistically. A gypsum replica of upper arm for young male was made and scanned for extracting the 3D coordinates of 4 feature points of shoulder point, the anterior/posterior armpit point and the axillary point describing the real arm-root shape under the normalized definitions, and the 5 landmarks were confirmed additionally for improving the fitting precision. Then, the wholly and piecewise fitting of arm-root curve with 9 feature points and mark points in total were generated respectively based on least square polynomial fitting method. Comparing to the wholly fitting, the piecewise fitted function segmented by the line between anterior and posterior axillary points showed a high fitting degree of arm-root morphology with R-square of 1, the length difference between fitted curve and gypsum curve is 0.003 cm within error range. And it provided a basic curve model with standard feature points to simulate arm-root morphology realistically by curve fitting for accurate body measurement extraction.

关键词： Arm-Root Morphology Curve-Fitting feature point Piecewise Curve Fitting Arm-Root Curve Simulation

Vehicular Electronic Image Stabilization System Based on a Gasoline Model Car Platform

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Chinese Journal of Mechanical Engineering 2022年第6期35卷 351-362页

作者： Ning Zhang Yuan Yang Jianhua Wu Ziqian Zhao Guodong Yin School of Mechanical Engineering Southeast UniversityNanjing 211189China School of Instrument Science and Engineering Southeast UniversityNanjing 210096China

Noise,vibration and harshness(NVH)problems in vehicle engineering are always challenging in both traditional vehicles and intelligent *** high accuracy manufacturing,modern structural roads and advanced suspension technology have already significantly reduced NVH problems and their impacts;off-road condition,obstacles and extreme operating condition could still trigger NVH problems *** paper proposes a vehicular electronic image stabilization(EIS)system to solve the vibration problem of the camera and ensure the environment perceptive function of ***,feature point detection and matching based on an oriented FAST and rotated BRIEF(ORB)algorithm are implemented to match images in the process of ***,a novel improved random sampling consensus algorithm(i-RANSAC)is proposed to eliminate mismatched feature points and increase the matching accuracy *** an adaptive Kalman filter(AKF)is applied to improve the adaptability of the vehicular ***,an experimental platform based on a gasoline model car was established to validate its *** experimental results show that the proposed EIS system can satisfy vehicular performance requirements even under off-road condition with obvious obstacles.

关键词： Electronic image stabilization Environment perceptive function feature point Adaptive Kalman filter Gasoline model car

Model of Autonomous Positioning Through Associating Environment Memory Information

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Transactions of Nanjing University of Aeronautics and Astronautics 2016年第5期33卷 584-594页

作者： Du Jia Wu Dewei Zhou Yang College of Information and Navigation Air Force Engineering University Xi'an 710077 P. R. China Xi'an Communications Institute Xi'an 710065 P.R. China

A model of autonomous positioning through associating environment memory information is presented for unmanned combat aerial vehicle(UCAV).The representation strategy of environment by constructing place cells is used to produce the memory information,and the landmarks in memory are retrieved through perceiving and processing the *** UCAV′s flight,the landmarks are obtained in real-time and are matched with the landmarks in ***,the idea of ranging positioning is adopted to calculate UCAV′s location based on the corresponding relationship between current obtained landmarks and the memorized *** shows that the proposed model can realize autonomous positioning in the memorized environment,and the positioning performance is well when the sensor has a high precision.

关键词： autonomous positioning environment memory environment representation landmarkst positioning feature point

Curve fitting and optimal interpolation on CNC machines based on quadratic B-splines

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Science China(Information Sciences) 2011年第7期54卷 1407-1418页

作者： ZHANG Mei 1,YAN Wei 2,YUAN ChunMing 1,WANG DingKang 1 & GAO XiaoShan 1 1 Key Laboratory of Mathematics Mechanization,Academy of Mathematics and Systems Science,Chinese Academy of Sciences,Beijing 100190,China 2 Research Institute of Petroleum Exploration and Development,Beijing 100083,China 1. Key Laboratory of Mathematics Mechanization Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China2. Research Institute of Petroleum Exploration and Development Beijing 100083 China

In this paper,curve fitting of 3-D points generated by G01 codes and interpolation based on quadratic B-splines are *** points of G01 codes are selected using an adaptive ***,quadratic B-splines are obtained as the fitting curve by interpolating these feature *** required in implementing the velocity planning algorithm mentioned by Timer et *** very complicated because of the appearance of high-order *** improved time-optimal method for the quadratic B-spline curves is presented to circumvent this *** algorithms are verified with simulations as well as on real CNC machines.

关键词： quadratic B-spline G01 codes feature point velocity planning interpolation