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Local and global interpretation of moving images
158
BOOK REVIEWS
Chapter 3, on dynamics, deals with the derivation of t h e dynamic equations of motion in both Lagrangian and Newton-Euler formulations and their use for simulation and control, and for identification of inertial parameters. Chapter 4 develops the concept of the manipulability ellipsoid and manipulability measure which provide a greater insight into the more-complex configurations of robotic mechanisms. The second half of the book focuses on the control of robot manipulator~. Various position-control algorithms that guide the manipulator's end effector along a desired trajectory are described in Chap. 5. Two typical methods used to control the contact force between the end effector and its environment are detailed in Chap. 6. For manipulators with redundant degrees of freedom, a technique to develop control algorithms for active utilization of the redundancy, an exceptionally advanced subject, is discussed in Chap. 7. The section of Appendices is one of the most useful parts of the book which leads the reader into a deeper understanding of the various complex mathematical concepts in robotic theory used throughout the book. It also gives compact reviews on the use of the function atan2, pseudo-inverses used in identification of manipulator dynamics, singular value decomposition, and Lyapunov stability theorems. There is only one minor point which may cause some problems for a few readers, namely the notation using front superscripts as well as subscripts for the designation of transformation matrices. R. Paul's matrix notation should be accepted as the standard form for the presentation of homogeneous transformation equations. Finally, in general, it should be said that this book will help considerably to smooth the way, particularly for postgraduate students, lecturers and even robot experts wishing to study the high-level topology of robotic science. The book can be recommended as a scholarly presentation of the current era's advanced robotics theories not adequately covered elsewhere.
sequences. Despite the extensive literature published on the subject of computational optic flow, some very basic problems remain unsolved. This book, titled "Local and Global Interpretation of Moving Images", written on the basis of the author's doctoral thesis at the University of Sussex in 1986, aims to summarize the main themes of optical flow theory, and highlights the dificulties encountered in the context of the processing of real images. The style of this book takes the form of an extended commentary and discussion of the applicabilities of various well-known algorithms of computing optical flow. The author also describes a number of algorithms with broad applications, some of which have found their way into working vision systems in Britain. New algorithms proposed are analysed and illustrated with examples showing the effectiveness of processing with synthetic and real-world "London Bus" images. The whole text consists of five chapters, ranging from local estimates of a velocity field to the global interpretation of motion parameters. The first chapter deals with obtaining local estimates of motion. The author discusses the aperture problem of Horn-Schunck's motion constraint equation for computing optical flow. It is also pointed out that neither point-tracking nor edge-tracking procedures for estimating flow vectors can provide reliable values of their horizontal and vertical components. A novel method of obtaining motion constraints, called "the principal axis procedure", is proposed, which unifies the edge-tracking, grey-level gradient and featurematching approaches, and which has been applied to the London Bus images. The second chapter covers the 3-D interpretation of velocity images. Tasks in 3-D interpretation include the estimation of 3-Dimensional translation and rotational parameters from 2-D velocity images. Two algorithms, LH1 and LH2, are developed for the computation of 3-D motion parameters in the cases of an object with arbitrary shape and of a plane, respectively. Certain computational issues relating to degeneracy, ambiguity of solutions, the aperture problem, narrow viewing FRANCIS N.-NAGY angles and nonrigid motion are clarified. Two algorUniversity of Salford, Salford ithms, SOl and SO2, for the case of "small object approximation" are also proposed. By repeatedly applying the small object algorithm at locations dispersed across the image one can obtain a global interLocal and Global Interpretation of Moving Images, pretation of moving images. The third chapter is focused on the practical appliResearch Notes in Artificial Intelligence, by GUY L. SCOTT. Pitman, London (1988). £15.95, ISBN No: cation of the proposed algorithm to noisy image data. When data obtained from the real world or the flow 0-273-08784-3. field calculated from noisy images are used, the algorThe term "optical flow" was first used by the American ithms LH 1 and LH2 present us with problems. It is not psychologist James Jerome Gibson (1904-1979) in his possible in general to acquire the least square solution study of human visual perception. It was originally by straightforward application of these algorithms. A proposed to designate the motion of a visual pattern new algorithm GLS1 was developed and compared perceived on the human retina. Researchers in with the others. The algorithms SO1 and SO2 proposed computer vision use optical flow images as an essential in chapter 2 were also tested on real data with some means to describe a motion analysis of image measure of success.
BOOK REVIEWS In chapter 4 the author looks at locally-based computation of optical flow, well-known as the Horn-Schunck algorithm, or the "MIT algorithm", according to the author. The concept of .smoothness, which forms the basis of computation with least square resolution, is discussed. A number of pertinent questions in relation to the smoothing approach of these algorithms are also pointed out. In addition, a P-vector, describing the 3-D velocity field of motion interpretation, is introduced instead of the 2-D velocity field in motion interpretation of the perspective planar case. The new vector has a constraint equation of the first order for image coordinates being one order less than that of the 2-D velocity vector. The constraint equation of the P-vector forms a constraint plane of P. Unlike the MIT algorithms, estimates of the P-vector can be recovered by an analogous smoothing procedure, subject to the data constraints on P. Computational results, comparing the accuracy of I-field and P-field estimates, show the superiority to the latter. At the end of this chapter an algorithm GLS2, combining global rigidity with local smoothness, is developed and demonstrated. Chapter 5 concerns the problem of discontinuity of the flow field and the segmentation problem of moving images. Here the author presents the "4-line" algorithm which exploits a symmetry between the distribution of potential matches and the distribution of currently estimated velocities in a neighbourhhod. The 4line algorithm extends the "principal axis procedure" of chapter one to extract linear constraints from the neighbourhood velocity field surrounding each pixel. Simulation results indicate that the new algorithm exhibits appropriate behaviour at flow boundaries between two smooth fields and in a field derived from rigid motion of a rough surface. In summary, this book provides a special reference report for researchers in the areas of computer vision or image data compression. Readers with experience in computation of optical flow and of motion parameter estimation, may find in it much that is useful and interesting in solving the incompletely resolved problem of the interpretation of moving images. A list of the literature has been provided, which is of benefit for further study and review of a broad range of related topics. YUAN BAO-ZONG
Northern Jiaotong University Beijing
Communications for Manufacturing Proceedings of the Open Congress, edited by S. WITHNELL and W. VAN PUYMBROECK. Springer, Berlin (1990). 285 pp., DM 130.00, ISBN No: 3-540-19642-0. Computer Integrated Manufacturing (CIM), now-
159
adays, is no longer a strategy for the future. Different investigations and implementations all over the world have been initiated with the aim of manufacturing automation. One of the key elements of these CIM projects is the communication between different computer-based devices produced by various manufacturing vendors. This book contains the Proceedings of
the Open Communications Congress on the Subject of Communications for Manufacturing, held in September 1990 in Stuttgart, Germany. Experts from different countries addressed the industrial needs of open systems for manufacturing, and explained the technological solutions enabling a multi-vendor environment and full integration from design to manufacture. The first section, user perspectives, comprises four papers from different industrial backgrounds describing the integration strategy, requirements, and their own achievements. One of the papers, presented by J. J. Michel (France) has analyzed CIM requirements from small and medium enterprises' point of view, which is the first such paper I have seen and which is of importance for the manufacturing automation markets. The second section, international initiatives, introduces two of the international efforts in standardizing industrial communications. One is FAIS (Factory Automation Interconnection System) and the other is CNMA (Communications Network for Manufacturing Applications). FAIS is a research and development project to develop a unified interconnection technology for automatic industrial equipment. CNMA is an industry-driven Europe-based research program aiming at furthering the development and adoption of industrial communication standards for CIM. The third section, implementation strategies, includes papers from the vendors' point of view, on how to adopt an open system and how to combine their products with the new open system development. Again, one of the articles is dedicated to small- and medium-sized enterprises. The fourth section, an introduction to CNMA and MAP, reviews the CNMA projects in reasonable detail. It describes the different stages and commitments of the project and outlines the further efforts required to put them into real applications. A paper on user requirements for communications is also included. The fifth section, open system protocols and specifications, briefly discusses the CNMA project from the technical point of view. Of especial interest is a paper dedicated to network management, which is a crucial element in open systems. Also, some results from prior testing efforts are presented. The final section, implementing open systems, contains different open system implementation reports. Various efforts and products are discussed, and lists of current commercial products are overviewed. Generally speaking, this is a well-selected book which will be relevant to a wide range of readers, from academics and researchers to manufacturers. It outlines
BOOK REVIEWS
Chapter 3, on dynamics, deals with the derivation of t h e dynamic equations of motion in both Lagrangian and Newton-Euler formulations and their use for simulation and control, and for identification of inertial parameters. Chapter 4 develops the concept of the manipulability ellipsoid and manipulability measure which provide a greater insight into the more-complex configurations of robotic mechanisms. The second half of the book focuses on the control of robot manipulator~. Various position-control algorithms that guide the manipulator's end effector along a desired trajectory are described in Chap. 5. Two typical methods used to control the contact force between the end effector and its environment are detailed in Chap. 6. For manipulators with redundant degrees of freedom, a technique to develop control algorithms for active utilization of the redundancy, an exceptionally advanced subject, is discussed in Chap. 7. The section of Appendices is one of the most useful parts of the book which leads the reader into a deeper understanding of the various complex mathematical concepts in robotic theory used throughout the book. It also gives compact reviews on the use of the function atan2, pseudo-inverses used in identification of manipulator dynamics, singular value decomposition, and Lyapunov stability theorems. There is only one minor point which may cause some problems for a few readers, namely the notation using front superscripts as well as subscripts for the designation of transformation matrices. R. Paul's matrix notation should be accepted as the standard form for the presentation of homogeneous transformation equations. Finally, in general, it should be said that this book will help considerably to smooth the way, particularly for postgraduate students, lecturers and even robot experts wishing to study the high-level topology of robotic science. The book can be recommended as a scholarly presentation of the current era's advanced robotics theories not adequately covered elsewhere.
sequences. Despite the extensive literature published on the subject of computational optic flow, some very basic problems remain unsolved. This book, titled "Local and Global Interpretation of Moving Images", written on the basis of the author's doctoral thesis at the University of Sussex in 1986, aims to summarize the main themes of optical flow theory, and highlights the dificulties encountered in the context of the processing of real images. The style of this book takes the form of an extended commentary and discussion of the applicabilities of various well-known algorithms of computing optical flow. The author also describes a number of algorithms with broad applications, some of which have found their way into working vision systems in Britain. New algorithms proposed are analysed and illustrated with examples showing the effectiveness of processing with synthetic and real-world "London Bus" images. The whole text consists of five chapters, ranging from local estimates of a velocity field to the global interpretation of motion parameters. The first chapter deals with obtaining local estimates of motion. The author discusses the aperture problem of Horn-Schunck's motion constraint equation for computing optical flow. It is also pointed out that neither point-tracking nor edge-tracking procedures for estimating flow vectors can provide reliable values of their horizontal and vertical components. A novel method of obtaining motion constraints, called "the principal axis procedure", is proposed, which unifies the edge-tracking, grey-level gradient and featurematching approaches, and which has been applied to the London Bus images. The second chapter covers the 3-D interpretation of velocity images. Tasks in 3-D interpretation include the estimation of 3-Dimensional translation and rotational parameters from 2-D velocity images. Two algorithms, LH1 and LH2, are developed for the computation of 3-D motion parameters in the cases of an object with arbitrary shape and of a plane, respectively. Certain computational issues relating to degeneracy, ambiguity of solutions, the aperture problem, narrow viewing FRANCIS N.-NAGY angles and nonrigid motion are clarified. Two algorUniversity of Salford, Salford ithms, SOl and SO2, for the case of "small object approximation" are also proposed. By repeatedly applying the small object algorithm at locations dispersed across the image one can obtain a global interLocal and Global Interpretation of Moving Images, pretation of moving images. The third chapter is focused on the practical appliResearch Notes in Artificial Intelligence, by GUY L. SCOTT. Pitman, London (1988). £15.95, ISBN No: cation of the proposed algorithm to noisy image data. When data obtained from the real world or the flow 0-273-08784-3. field calculated from noisy images are used, the algorThe term "optical flow" was first used by the American ithms LH 1 and LH2 present us with problems. It is not psychologist James Jerome Gibson (1904-1979) in his possible in general to acquire the least square solution study of human visual perception. It was originally by straightforward application of these algorithms. A proposed to designate the motion of a visual pattern new algorithm GLS1 was developed and compared perceived on the human retina. Researchers in with the others. The algorithms SO1 and SO2 proposed computer vision use optical flow images as an essential in chapter 2 were also tested on real data with some means to describe a motion analysis of image measure of success.
BOOK REVIEWS In chapter 4 the author looks at locally-based computation of optical flow, well-known as the Horn-Schunck algorithm, or the "MIT algorithm", according to the author. The concept of .smoothness, which forms the basis of computation with least square resolution, is discussed. A number of pertinent questions in relation to the smoothing approach of these algorithms are also pointed out. In addition, a P-vector, describing the 3-D velocity field of motion interpretation, is introduced instead of the 2-D velocity field in motion interpretation of the perspective planar case. The new vector has a constraint equation of the first order for image coordinates being one order less than that of the 2-D velocity vector. The constraint equation of the P-vector forms a constraint plane of P. Unlike the MIT algorithms, estimates of the P-vector can be recovered by an analogous smoothing procedure, subject to the data constraints on P. Computational results, comparing the accuracy of I-field and P-field estimates, show the superiority to the latter. At the end of this chapter an algorithm GLS2, combining global rigidity with local smoothness, is developed and demonstrated. Chapter 5 concerns the problem of discontinuity of the flow field and the segmentation problem of moving images. Here the author presents the "4-line" algorithm which exploits a symmetry between the distribution of potential matches and the distribution of currently estimated velocities in a neighbourhhod. The 4line algorithm extends the "principal axis procedure" of chapter one to extract linear constraints from the neighbourhood velocity field surrounding each pixel. Simulation results indicate that the new algorithm exhibits appropriate behaviour at flow boundaries between two smooth fields and in a field derived from rigid motion of a rough surface. In summary, this book provides a special reference report for researchers in the areas of computer vision or image data compression. Readers with experience in computation of optical flow and of motion parameter estimation, may find in it much that is useful and interesting in solving the incompletely resolved problem of the interpretation of moving images. A list of the literature has been provided, which is of benefit for further study and review of a broad range of related topics. YUAN BAO-ZONG
Northern Jiaotong University Beijing
Communications for Manufacturing Proceedings of the Open Congress, edited by S. WITHNELL and W. VAN PUYMBROECK. Springer, Berlin (1990). 285 pp., DM 130.00, ISBN No: 3-540-19642-0. Computer Integrated Manufacturing (CIM), now-
159
adays, is no longer a strategy for the future. Different investigations and implementations all over the world have been initiated with the aim of manufacturing automation. One of the key elements of these CIM projects is the communication between different computer-based devices produced by various manufacturing vendors. This book contains the Proceedings of
the Open Communications Congress on the Subject of Communications for Manufacturing, held in September 1990 in Stuttgart, Germany. Experts from different countries addressed the industrial needs of open systems for manufacturing, and explained the technological solutions enabling a multi-vendor environment and full integration from design to manufacture. The first section, user perspectives, comprises four papers from different industrial backgrounds describing the integration strategy, requirements, and their own achievements. One of the papers, presented by J. J. Michel (France) has analyzed CIM requirements from small and medium enterprises' point of view, which is the first such paper I have seen and which is of importance for the manufacturing automation markets. The second section, international initiatives, introduces two of the international efforts in standardizing industrial communications. One is FAIS (Factory Automation Interconnection System) and the other is CNMA (Communications Network for Manufacturing Applications). FAIS is a research and development project to develop a unified interconnection technology for automatic industrial equipment. CNMA is an industry-driven Europe-based research program aiming at furthering the development and adoption of industrial communication standards for CIM. The third section, implementation strategies, includes papers from the vendors' point of view, on how to adopt an open system and how to combine their products with the new open system development. Again, one of the articles is dedicated to small- and medium-sized enterprises. The fourth section, an introduction to CNMA and MAP, reviews the CNMA projects in reasonable detail. It describes the different stages and commitments of the project and outlines the further efforts required to put them into real applications. A paper on user requirements for communications is also included. The fifth section, open system protocols and specifications, briefly discusses the CNMA project from the technical point of view. Of especial interest is a paper dedicated to network management, which is a crucial element in open systems. Also, some results from prior testing efforts are presented. The final section, implementing open systems, contains different open system implementation reports. Various efforts and products are discussed, and lists of current commercial products are overviewed. Generally speaking, this is a well-selected book which will be relevant to a wide range of readers, from academics and researchers to manufacturers. It outlines