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A snake-based scheme for path planning and control with constraints by distributed visual sensors

ROBOTICA 2014年第4期32卷 477-499页

作者： Cheng, Y. Jiang, P. Hu, Y. F. Univ Bradford Sch Engn Design & Technol Bradford BD7 1DP W Yorkshire England Univ Hull Dept Comp Sci Kingston Upon Hull HU6 7RX N Humberside England

This paper proposes a robot navigation scheme using wireless visual sensors deployed in an environment. Different from the conventional autonomous robot approaches, the scheme intends to relieve massive on-board information processing required by a robot to its environment so that a robot or a vehicle with less intelligence can exhibit sophisticated mobility. A three-state snake mechanism is developed for coordinating a series of sensors to form a reference path. Wireless visual sensors communicate internal forces with each other along the reference snake for dynamic adjustment, react to repulsive forces from obstacles, and activate a state change in the snake body from a flexible state to a rigid or even to a broken state due to kinematic or environmental constraints. A control snake is further proposed as a tracker of the reference path, taking into account the robot's non-holonomic constraint and limited steering power. A predictive control algorithm is developed to have an optimal velocity profile under robot dynamic constraints for the snake tracking. They together form a unified solution for robot navigation by distributed sensors to deal with the kinematic and dynamic constraints of a robot and to react to dynamic changes in advance. Simulations and experiments demonstrate the capability of a wireless sensor network to carry out low-level control activities for a vehicle.

关键词： snake algorithm Wireless visual sensors Mobile robot navigation Distributed robot system

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Design and implementation of gradient vector flow snake to detect a reference object in pelvic x-rays for preoperative total hip arthroplasty planning application

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JOURNAL OF DIGITAL IMAGING 2007年第4期20卷 373-380页

作者： Kristanto, W. van Ooijen, P. M. A. The, B. Duifhuis, H. Mengko, T. R. Oudkerk, M. Univ Med Ctr Groningen Dept Radiol NL-9700 RB Groningen Netherlands Univ Groningen Dept Biomed Engn NL-9700 RB Groningen Netherlands Inst Teknol Bandung Biomed Engn Elect Engn Dept Bandung 40132 Indonesia Univ Med Ctr Groningen Dept Orthoped NL-9700 RB Groningen Netherlands

The main interest of this research project is to promote automation in performing preoperative planning for hip joint replacement surgery using a special medical image viewing software, ViewPro (TM). Preoperative planning is performed to carefully prepare the surgery and to accurately select the hip implants. The first step of preoperative planning is to calibrate the x-ray image to adjust the magnification factor. A femoral head implant is used as magnification factor reference. Automation is introduced by developing an algorithm to automatically detect this reference object in the image. The algorithm used for performing the automatic detection of the reference object is gradient vector flow (GVF) snake. A study has been performed to compare the newly developed semiautomatic algorithm to the old manual calibration algorithm. The results show a close relation between the two algorithms (less than 1% of average relative difference). It is concluded that the developed semiautomated algorithm can be used as an alternative for performing the manual calibration.

关键词： preoperative planning total hip arthroplasty snake algorithm gradient vector flow

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snake in phase domain: A method for boundary detection of objects in phase images

Snake in phase domain: A method for boundary detection of ob...

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IEEE International Joint Conference on Neural Network

作者： Suksmono, Andriyan B. Handayani, Astri Hirose, Akira Inst Teknol Bandung Sch Elect Engn & Informat JI Ganesha 10 Bandung Bandung 40132 Indonesia Univ Tokyo Dept Elect & Elect Engn Bunkyo Ku Tokyo Japan

ISBN: (纸本)9780780394902

This paper presents a snake algorithm for boundary detection of objects in phase images. Since phase image is a modulo-2 pi field, the proper gradient vector field (GVF) for snake dynamics should be taken from an unwrapped phase. This paper proposes a procedure to avoid such unwrapping by applying modulo-2 pi gradient estimation. Performance assessment is conducted by comparing a boundary detection result of non-modulo-2 pi GVF snake estimate with a modulo-2 pi regularized GVF snake. It is shown that the proposed method converges to the expected boundary, while the non-regularized procedure does not.

关键词： snake algorithm gradient vector flow energy minimization algorithm phase image modulo-2 pi regularization InSAR MRI phase unwrapping

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Robust Segmentation of Intima-Media Borders With Different Morphologies and Dynamics During the Cardiac Cycle

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IEEE JOURNAL OF BIOMEDICAL AND HEALTH INFORMATICS 2018年第5期22卷 1571-1582页

作者： Zhao, Shen Gao, Zhifan Zhang, Heye Xie, Yaoqin Luo, Jianwen Ghista, Dhanjoo Wei, Zhanghong Bi, Xiaojun Xiong, Huahua Xu, Chenchu Li, Shuo Chinese Acad Sci Shenzhen Inst Adv Technol Inst Biomed & Hlth Engn Shenzhen 518055 Peoples R China Chinese Acad Sci Shenzhen Inst Adv Technol Inst Adv Comp & Digital Engn Shenzhen 518055 Peoples R China Tsinghua Univ Sch Med Dept Biomed Engn Beijing 100084 Peoples R China Univ 2020 Fdn Northborough MA USA Shenzhen Peoples Hosp Shenzhen Peoples R China Tongji Hosp Wuhan 430030 Hubei Peoples R China Second Hosp Shenzhen Shenzhen 518055 Peoples R China Anhui Univ Hefei Anhui Peoples R China Univ Western Ontario London ON N6A 3K7 Canada

Segmentation of carotid intima-media (IM) borders from ultrasound sequences is challenging because of unknown image noise and varying IM border morphologies and/or dynamics. In this paper, we have developed a state-space framework to sequentially segment the carotid IM borders in each image throughout the cardiac cycle. In this framework, an H-infinity filter is used to solve the state-space equations, and a grayscale-derivative constraint snake is used to provide accurate measurements for the H-infinity filter. We have evaluated the performance of our approach by comparing our segmentation results to the manually traced contours of ultrasound image sequences of three synthetic models and 156 real subjects from four medical centers. The results show that our method has a small segmentation error (lumen intima, LI: 53 +/- 67 mu m;media-adventitia, MA: 57 +/- 63 mu m) for synthetic and real sequences of different image characteristics, and also agrees well with the manual segmentation (LI: bias = 1.44 mu m;MA: bias = -3.38 mu m). Our approach can robustly segment the carotid ultrasound sequences with various IM border morphologies, dynamics, and unknown image noise. These results indicate the potential of our framework to segment IM borders for clinical diagnosis.

关键词： Carotid artery H-infinity filter IM borders snake algorithm ultrasound image sequences

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Videokymographic image processing: Objective parameters and user-friendly interface

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BIOMEDICAL SIGNAL PROCESSING AND CONTROL 2012年第2期7卷 192-201页

作者： Manfredi, Claudia Bocchi, Leonardo Cantarella, Giovanna Peretti, Giorgio Univ Florence Dept Elect & Telecommun I-50139 Florence Italy Fdn IRCCS Osped Maggiore Policlin Mangiagalli & Regina Elen Dept Otolaryngol Milan Italy Spedali Civili Brescia Clin Otolaryngol Brescia Italy

Videolaryngostroboscopy (VLS) is undoubtedly a first choice examination technique in the diagnosis of several laryngeal pathologies. However, in case of low intensity or strong a-periodicity of the vocal sound, the VLS mechanism becomes ineffective in describing subsequent phases of the vocal cycle. To overcome such limitations, a new technique, called videokymography (VKG), was developed. VKG delivers images and displays the vibratory pattern from a single line selected from the whole VLS image, at the speed of approximately 8000 line-images/s. Despite its usefulness, parameter evaluation has been mostly based on visual inspection and no quantitative analysis of videokymographic images is commercially available at this time. This article presents the VKG-Analyser, a new tool for measuring and tracking quantitative parameters from VKG images. Specifically, the left-to-right period, amplitude and phase ratios and phase symmetry index were evaluated. The case of incomplete glottis closure, the minimum distance between folds was implemented. A digital image processing algorithm was developed and optimised for the analysis of VKG recordings that require intensity adjustment, noise removal and robust techniques for edge detection to avoid fluctuations of the grey levels in regions far from the vocal folds. The VKG-Analyser relies on a user-friendly interface that allows for the storage and retrieval of patients' data and optimises the image analysis, according to a set of parameters that can be manually adjusted by the user. It was successfully tested on a set of synthetic images and applied to real VKG images, both in the case of complete and incomplete glottis closure. The new software tool aims to provide fast, reliable and reproducible measures. When applied to a large set of data, it can define reference values for normal and pathological cases, providing a valid support for diagnosis and evaluation of surgical effectiveness. (C) 2011 Elsevier Ltd. All rights reserv

关键词： Vocal folds vibration Videokymographic images snake algorithm Greedy algorithm Contour detection Objective measures User-friendly interface

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Video object tracking with a sequential hierarchy of template deformations

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 2001年第11期11卷 1171-1182页

作者： Schoepflin, T Chalana, V Haynor, DR Kim, Y Univ Washington Dept Elect Engn Seattle WA 98195 USA Univ Washington Dept Bioengn Seattle WA 98195 USA Insightful Com Seattle WA 98109 USA Univ Washington Dept Radiol Seattle WA 98195 USA

We have developed a new contour-based tracking algorithm that uses a sequence of template deformations to model and track generic video objects. We organize the deformations into a hierarchy: globally affine deformations, piecewise (locally) affine deformations, and arbitrary smooth deformations (snakes). This design enables the algorithm to track objects whose pose and shape change in time compared to the template. If the object is not a rigid body, we model the temporal evolution of its shape by updating the entire template after each video frame;otherwise, we only update the pose of the object. Experimental results demonstrate that our method is able to track a variety of video objects, including those undergoing rapid changes. We quantitatively compare our algorithm with its constituent pieces (e.g., the snake algorithm) and show that the complete algorithm can track objects with moving parts for a longer duration than partial versions of the hierarchy. It could be benefited from a higher level algorithm to dynamically adjust the parameters and template deformations to improve the segmentation accuracy further. The hierarchical nature of this algorithm provides a framework that offers a modular approach for the design and enhancement of future object-tracking algorithms.

关键词： deformable templates local templates segmentation quality snake algorithm video segmentation

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Object segmentation algorithm using snakes in stereo images

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OPTICAL ENGINEERING 2006年第3期45卷 037005-1-037005页

作者： Kim, Shin-Hyoung Jang, Jong-Whan Choi, Jae-Ho PaiChai Univ Dept Informat & Commun Engn Taejon 302435 South Korea Chonbuk Natl Univ Dept Comp Engn Chonju 561756 Chonbuk South Korea

A snake-based algorithm for segmenting an object from a pair of stereo images is presented. Unlike previously developed snake-based algorithms, this one performs well even when the objects in the picture are occluded and the background behind them is cluttered. Also, the algorithm is not sensitive to the placement of the initial snake points. The algorithm uses a new energy function defined over the disparity space between the pair of the stereo images to successfully locate the boundary of an object in a complex image. Experimental results have shown that the developed algorithm produces more accurate segmentation results than those of the well-known conventional snake algorithm reported by Kass et al. (c) 2006 Society of Photo-Optical Instrumentation Engineers.

关键词： object segmentation snake algorithm stereo images disparity space disparity information energy function

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Dynamic clustering and propagation of congestion in heterogeneously congested urban traffic networks

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TRANSPORTATION RESEARCH PART B-METHODOLOGICAL 2017年 105卷 193-211页

作者： Saeedmanesh, Mohammadreza Geroliminis, Nikolas Ecole Polytech Fed Lausanne Sch Architecture Civil & Environm Engn Urban Transport Syst Lab GC C2 390Stn 18 CH-1015 Lausanne Switzerland

The problem of clustering in urban traffic networks has been mainly studied in static framework by considering traffic conditions at a given time. Nevertheless, it is important to underline that traffic is a strongly time-variant process and it needs to be studied in the spatiotemporal dimension. Investigating the clustering problem over time in the dynamic domain is critical to better understand and reveal the hidden information during the process of congestion formation and dissolution. The primary motivation of the paper is to study the spatiotemporal relation of congested links, observing congestion propagation from a macroscopic perspective, and finally identifying critical pockets of congestion that can aid the design of peripheral control strategies. To achieve this, we first introduce a static clustering method to partition the heterogeneous network into homogeneous connected sub-regions. The proposed framework guarantees connectivity of the cluster in different steps, which eases the development of a dynamic framework. The proposed clustering approach has 3 steps;firstly, it obtains a set of homogeneous connected components in the network. Each component has a form of sequence which is built by sequentially adding neighboring links with similar level of congestion. Secondly, the major skeleton of clusters is obtained out of this feasible set by minimizing a heterogeneity index. Thirdly, a fine-tuning step is designed to complete the clustering task by assigning the unclustered links of the network to proper clusters while keeping the connectivity. The optimization problem in both second and third step is formulated as a mixed integer linear programming. The approach is also extended to capture spatiotemporal growth and formation of congestion. The dynamic clustering is based on an iterative and fast procedure that considers the spatiotemporal characteristics of congestion propagation and identifies the links with the highest degree of heterogeneity due to t

关键词： Graph partitioning Congestion propagation Asggregate modeling Mixed integer linear programming snake algorithm

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Closed contour edge detection of blood vessel lumen and outer wall boundaries in black-blood MR images

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MAGNETIC RESONANCE IMAGING 1999年第2期17卷 257-266页

作者： Yuan, C Lin, E Millard, J Hwang, JN Univ Washington Sch Med Dept Radiol Seattle WA 98195 USA

Quantitative measurements of the blood vessel wall area may provide useful information of atherosclerotic plaque burden, progression and/or regression. Magnetic resonance imaging is a promising technique for identifying both luminal and outer wall boundaries of the human blood vessels. Currently these boundaries are primarily defined manually, a process viewed as labor intensive and subject to significant operator bias. Fully automated post-processing techniques used for identifying the lumen and wall boundaries, on the other hand, are also problematic due to the complexity of signal features in the vicinity of the blood vessels. The goals of this study were to develop a robust, automated closed contour edge detection algorithm, apply this algorithm to high resolution human carotid artery images, and assess its accuracy, and reproducibility, Our algorithm has proven to be sensitive to various contrast situations and is reasonably accurate and highly reproducible. (C) 1999 Elsevier Science Inc.

关键词： edge detection snake algorithm atherosclerotic plaque

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An approach for prediction of shoreline with spatial uncertainty mapping (SLiP-SUM)

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INTERNATIONAL JOURNAL OF APPLIED EARTH OBSERVATION AND GEOINFORMATION 2018年 73卷 546-554页

作者： San, Bekir Taner Ulusar, Umit Deniz Akdeniz Univ Dept Geol Engn Dumlupinar Blv TR-07058 Antalya Turkey Akdeniz Univ Dept Comp Engn Dumlupinar Blv TR-07058 Antalya Turkey

This study puts forward a semi-automatic shoreline detection and future prediction with spatial uncertainty algorithm called the SUP-SUM (Shore Line Prediction with Spatial Uncertainty Mapping), which has five main steps: (1) preprocessing of data sets (i.e. aerial photos and/or satellite images), (2) extraction or delineation of the existing shorelines with snake algorithm, 3) prediction of the future shorelines using linear regression, (4) preparation of the spatial uncertainty mapping using cokriging, and (5) producing possible shoreline with spatial uncertainty. The proposed approach was tested on the coast of Kumluca, a dynamic coastal area in Turkey, and future shoreline predictions were made for 2020, 2025, 2030 and 2035 based on remotely sensed data (aerial photos and WorldView-2 images) acquired between 1971 and 2014. A cokriging interpolation technique was adopted that takes into account both estimation errors and the spatial resolution of the source data sets for the mapping of spatial uncertainty. The results indicate that the maximum and minimum annual changes of shoreline were -2.29 m/yr (transgression) in the west-central part of the study area, and + 0.36 m/yr (regression) in the east part. The general trend of the future shoreline regime was transgressional, and the mean uncertainty values along the predicted shorelines for 2020, 2025, 2030 and 2035 were 6.78 m, 2.02 m, 6.76 m and 7.06 m, respectively.

关键词： Shoreline prediction Spatial uncertainty mapping snake algorithm SLiP SUM Antalya

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