Showing papers on "Object (computer science) published in 1991"

Color indexing

Abstract: Computer vision is moving into a new era in which the aim is to develop visual skills for robots that allow them to interact with a dynamic, unconstrained environment. To achieve this aim, new kinds of vision algorithms need to be developed which run in real time and subserve the robot's goals. Two fundamental goals are determining the identity of an object with a known location, and determining the location of a known object. Color can be successfully used for both tasks. This dissertation demonstrates that color histograms of multicolored objects provide a robust, efficient cue for indexing into a large database of models. It shows that color histograms are stable object representations in the presence of occlusion and over change in view, and that they can differentiate among a large number of objects. For solving the identification problem, it introduces a technique called Histogram Intersection, which matches model and image histograms and a fast incremental version of Histogram Intersection which allows real-time indexing into a large database of stored models. It demonstrates techniques for dealing with crowded scenes and with models with similar color signatures. For solving the location problem it introduces an algorithm called Histogram Backprojection which performs this task efficiently in crowded scenes.

Wait-free synchronization

Abstract: A wait-free implementation of a concurrent data object is one that guarantees that any process can complete any operation in a finite number of steps, regardless of the execution speeds of the other processes. The problem of constructing a wait-free implementation of one data object from another lies at the heart of much recent work in concurrent algorithms, concurrent data structures, and multiprocessor architectures. First, we introduce a simple and general technique, based on reduction to a concensus protocol, for proving statements of the form, “there is no wait-free implementation of X by Y.” We derive a hierarchy of objects such that no object at one level has a wait-free implementation in terms of objects at lower levels. In particular, we show that atomic read/write registers, which have been the focus of much recent attention, are at the bottom of the hierarchy: thay cannot be used to construct wait-free implementations of many simple and familiar data types. Moreover, classical synchronization primitives such astest&set and fetch&add, while more powerful than read and write, are also computationally weak, as are the standard message-passing primitives. Second, nevertheless, we show that there do exist simple universal objects from which one can construct a wait-free implementation of any sequential object.

Rete: a fast algorithm for the many pattern/many object pattern match problem

Abstract: The Rete Match Algorithm is an efficient method for companng a large collection of patterns to a large collection of objects. It finds all the objects that match each pattern The algorithm was developed for use in production system interpreters, and it has been used for systems containing from a few hundred to more than a thousand patterns and objects. This article presents the algorithm in detail It explains the basic concepts of the algorithm, it describes pattern and object representations that are appropriate for the algorithm, and it describes the operations performed by the pattern matcher.

Object-oriented software engineering

Abstract: A text on industrial system development using object- oriented techniques, rather than a book on object-oriented programming. Will be useful to systems developers and those seeking a deeper understanding of object orientation as it relates to the development process.

Eiffel: The Language

Abstract: Introduction Basic Conventions Classes, Universes, and Systems: The Architecture of Eiffel Software Storing Class Texts Classes Features Inheritance Clients and Exports Types Conformance Routines and Instructions Assertions, Specifications, and Correctness Control Structures Exceptions Attributes Objects, Values, Expressions, and Entities Object Creation Re-attachment Feature Call Expressions and Constants Universal Features Persistance and Environments Arrays and Strings Input and Output Interfacing with Other Languages Appendix A. An Introduction to Eiffel Appendix B. Style Guidelines Appendix C. Reserved Words and Special Symbols Appendix D. Syntax Summary Appendix E. Syntax in Alphabetical Order Index

The dynamics of collective sorting robot-like ants and ant-like robots

Abstract: A distributed sorting algorithm, inspired by how ant colonies sort their brood is presented for use by robot teams The robots move randomly, do not communicate have no hierarchical organisation, have no global representation can only perceive objects just in front of them, but can distinguish between objects of two or more types with a certain degree of error The probability that they pick up or put down an object is modulated as a function of how many of the same objects they have met in the recent past This generates a positive feed-back that is sufficient to coordinate the robots' activity, resulting in their sorting the objects into common clusters While less efficient than a hierarchically controlled sorting, this decentralised organisation offers the advantages of simplicity, flexibility and robustness

Recognition by linear combinations of models

Abstract: An approach to visual object recognition in which a 3D object is represented by the linear combination of 2D images of the object is proposed. It is shown that for objects with sharp edges as well as with smooth bounding contours, the set of possible images of a given object is embedded in a linear space spanned by a small number of views. For objects with sharp edges, the linear combination representation is exact. For objects with smooth boundaries, it is an approximation that often holds over a wide range of viewing angles. Rigid transformations (with or without scaling) can be distinguished from more general linear transformations of the object by testing certain constraints placed on the coefficients of the linear combinations. Three alternative methods of determining the transformation that matches a model to a given image are proposed. >

Object Recognition by Computer: The Role of Geometric Constraints

Abstract: With contributions from Tomas LozanoPerez and Daniel P. Huttenlocher.An intelligent system must know "what "the objects are and "where "they are in its environment. Examples of this ubiquitous problem in computer vision arise in tasks involving hand-eye coordination (such as assembling or sorting), inspection tasks, gauging operations, and in navigation and localization of mobile robots. This book describes an extended series of experiments into the role of geometry in the critical area of object recognition. It provides precise definitions of the recognition and localization problems, describes the methods used to address them, analyzes the solutions to these problems, and addresses the implications of this analysis.The solution to problems of object recognition are of fundamental importance in many real applications and versions of the techniques described here are already being used in industrial settings. Although a number of questions remain to be solved, the authors provide a valuable framework for understanding both the strengths and limitations of using object shape to guide recognition.W. Eric L. Grimson is Matsushita Associate Professor in the Department of Electrical Engineering and Computer Science at MIT.Contents: Introduction. Recognition as a Search Problem. Searching for Correspondences. Two-Dimensional Constraints. Three-Dimensional Constraints. Verifying Hypotheses. Controlling the Search Explosion. Selecting Subspaces of the Search Space. Empirical Testing. The Combinatorics of the Matching Process. The Combinatorics of Hough Transforms. The Combinatorics of Verification. The Combinatorics of Indexing. Evaluating the Methods. Recognition from Libraries. Parameterized Objects. The Role of Grouping. Sensing Strategies. Applications. The Next Steps.

Updating local copy of shared data in a collaborative system

Abstract: A multi-user collaborative system in which the contents as well as the current status of other user activity of a shared structured data object representing one or more related structured data objects in the form of data entries can be concurrently accessed by different users respectively at different workstations connected to a common link. The WYSIWIS user interface representation of the shared structured data object includes an ordered listing of such entries that are maintained by the structured data object and various attributes of each listed entry, inter alia, the type and class of entry; the revision number of the shared structured data object; the number of pages and revision number of each structured data object entry; the date of creation and last revision of each such entry; whether an entry can be accessed by a user and, if not, who has prevented such access; whether a local instance of an entry is present on a user's system; and a provision for miscellaneous notes or comments relative to each entry for view by other users. Means is provided for maintaining current information relative to the shared structured object and its entries on a user initiated demand updated basis invoked by a user operation, which operation requires updated information to properly implement the operation. Further, means is provided for locking up one or more data entries by an individual user and thereby prevent access of the locked entries by other users to prevent concurrent editing and other changes to the same entries by two or more users. In this connection, editing or modification cannot be performed by a user until the shared structured data object entry or entries have been locked up. Visual indication as to the locked state of entries and other information relative to the locking user and the time of lock is updated and displayed in the shared structured data object representation present at user workstations when a use invokes a user operation on the shared structured data object or its contents.

An alternating digital tree (ADT) algorithm for 3D geometric searching and intersection problems

Abstract: A searching algorithm is presented for determining which members of a set of n points in an N dimensional space lie inside a prescribed space subregion. The algorithm is then extended to handle finite size objects as well as points. In this form it is capable of solving problems such as that of finding the objects from a given set which intersect with a prescribed object. The suitability of the algorithm is demonstrated for the problem of three dimensional unstructured mesh generation using the advancing front method.

Fractal computer user centerface with zooming capability

Abstract: A computer user interface that represents information stored in a computer as reprentation objects located on at least one reference surface is disclosed. A user can magnify or reduce the displayed information by "zooming" in or out. The magnification operation displays a smaller portion of a particular surface, but each object that remains in view is displayed in greater size and/or detail. Similarly, the reduction operation displays a larger portion of a given surface, but each object within such surface is displayed in a smaller size and/or less detail. In order to view one part of the surface from another part of the surface or from another surface, a special type of an object, called a representation portal object, is provided. A graphical description of each object is physically stored in computer memory essentially as a sequence of compressed image representations. The first image in the sequence is a bit-mapped representation of an object as it was created, and each subsequent image is a reduced copy of the first image.

A system and method for database management supporting object-oriented programming

Abstract: A system and method for database management for providing support for long-term storage and retrieval of objects created by application programs written at least in part in object-oriented programming languages consists of a plurality of software modules. These modules provide data definition language translation, object management, object translation, and persistent object storage service. Such system implements an object fault capability to reduce the number of interactions between the application, the database management system, and the database.

Volumetric shape description of range data using “Blobby Model”

Abstract: Recently in the field of computer vision, there have been many attempts to obtain a symbolic shape description of an object by fitting simple primitives to the range data of the object. In this paper, we introduce the "Blobby Model" for automatically generating a shape description from range data. This model can express a 3D surface as an isosurface of a scalar field which is produced by a number of field generating primitives. The fields from many primitives are blended with each other and can form a very complicated shape. To determine the number and distribution of primitives required to adequately represent a complex 3D surface, an energy function is minimized which measures the shape difference between the range data and the "Blobby Model". We start with a single primitive and introduce more primitives by splitting each primitive into two further primitives so as to reduce the energy value. In this manner, the shape of the 3D object is slowly recovered as the isosurface produced by many primitives. We have successfully applied this method to human face range data and typical results are shown. The method herein does not require any prior range segmentation.

Method for providing user access control within a distributed data processing system by the exchange of access control profiles

Abstract: A method is disclosed for providing user access control for a plurality of resource objects within a distributed data processing system having a plurality of resource managers. A reference monitor service is established and a plurality of access control profiles are stored therein. Thereafter, selected access control profiles are exchanged between the reference monitor service and a resource manager in response to an attempted access (82) of a particular resource object controlled by that resource manager. The resource manager may then control access to the resource object by utilizing the exchanged access control profile (86-98). In a preferred embodiment of the present invention, each access control profile may include access control information relating to a selected user; a selected resource object; a selected group of user; a selected set of resource objects; or, a predetermined set of resource objects and a selected group of users.

Object-oriented systems analysis: a model-driven approach

Abstract: 1. Introduction. 2. The Object-Relationship Model. 3. Object Behavior Models. 4. Building the System Specification. 5. Verifying the System Specification. 6. Preparing for System Design. 7. Two Case Studies.

Access control policies for an object oriented database, including access control lists which span across object boundaries

Abstract: The system and method of this invention provides an access control list which spans across object boundaries in an object oriented database. In addition to providing read and write access permissions, the access control list provides execute semantics which apply to the execution of methods in an object oriented database. Within the entries of the access control lists, each of the permissions for read, write, and execute can be assigned separately to each of a number of ids representing user ids or group ids. Upon request for access to the data by the user, the user id of the user and the group ids for which the user is a member are searched for within the entries to determine whether the user has the privileges to perform the operation requested against the objects. In addition, the access control policies are inherited from an object's superobject; resulting in a least privilege for the object.

The Pegasus heterogeneous multidatabase system

Abstract: Pegasus, a heterogeneous multidatabase management system that responds to the need for effective access and management of shared data across in a wide range of applications, is described. Pegasus provides facilities for multidatabase applications to access and manipulate multipole autonomous heterogeneous distributed object-oriented relational, and other information systems through a uniform interface. It is a complete data management system that integrates various native and local databases. Pegasus takes advantage of object-oriented data modeling and programming capabilities. It uses both type and function abstractions to deal with mapping and integration problems. Function implementation can be defined in an underlying database language or a programming language. Data abstraction and encapsulation facilities in the Pegasus object model provide an extensible framework for dealing with various kinds of heterogeneities in the traditional database systems and nontraditional data sources. >

Computer vision system for position monitoring in three dimensions using non-coplanar light sources attached to a monitored object

Abstract: A sensing system for monitoring the position and orientation of a rigid object (20). At least 4 point light sources (24) are mounted on the surface of the object (20) in a noncoplanar arrangement. A single electronic camera (26) captures images (59) of the point light sources (24). Locations of the images (59) of the light sources (24) are detected in each video image, and a computer runs a task using these locations to obtain close approximations of the rotation matrix and translation vector (33) of the object (20) in a camera coordinate system (74) at video rate. The object is held by an operator (90) for three-dimensional cursor (94) control and interaction with virtual reality scenes (96) on computer displays (88), and for remote interactive control of teleoperated mechanisms.

Methods and apparatus for implementing server functions in a distributed heterogeneous environment

Abstract: In distributed heterogeneous data processing networks, dispatcher and control server software components execute the code of a single application or of many portions of the code of one or more applications in response to a method object received from a client application. The method object includes a reference to the code to be executed.

Object-oriented database management systems: concepts and issues

Abstract: Requirements imposed on both the object data model and object management by the support of complex objects are outlined. The basic concepts of an object-oriented data model are discussed. They are objects and object identifiers, aggregation, classes and instantiation mechanisms, metaclasses, and inheritance. Object-oriented models are compared with semantic, relational, and Codasyl models. Object-oriented query languages and query processing are considered. Some operational aspects of data management in object-oriented systems are examined. Schema evolution is discussed. >

Distributed, object-based programming systems

Abstract: The development of distributed operating systems and object-based programming languages makes possible an environment in which programs consisting of a set of interacting modules, or objects, may execute concurrently on a collection of loosely coupled processors. An object-based programming language encourages a methodology for designing and creating a program as a set of autonomous components, whereas a distributed operating system permits a collection of workstations or personal computers to be treated as a single entity. The amalgamation of these two concepts has resulted in systems that shall be referred to as distributed, object-based programming systems.This paper discusses issues in the design and implementation of such systems. Following the presentation of fundamental concepts and various object models, issues in object management, object interaction management, and physical resource management are discussed. Extensive examples are drawn from existing systems.

Object-oriented framework for menu definition

Abstract: A declarative object-oriented approach to menu construction provides a mechanism for specifying the behavior, appearance and function of menus as part of an interactive user interface. Menus are constructed from interchangeable object building blocks to obtain the characteristics wanted without the need to write new code or code and maintaining a coherent interface standard. The approach is implemented by dissecting interface menu behavior into modularized objects specifying orthogonal components of desirable menu behaviors. Once primary characteristics for orthogonal dimensions of menu behavior are identified, individual objects are constructed to provide specific alternatives for the behavior within the definitions of each dimension. Finally, specific objects from each dimension are combined to construct a menu having the desired selections of menu behaviors.

Board game apparatus

Abstract: A board game apparatus comprises a board 10 marked with a seven-by-seven array 12 of squares having an inner five-by-five region 14 and a peripheral region 16. Two players play each using, for example, eighteen playing pieces and two blocking pieces, with the object to cause four of the opposing playing pieces to be arranged in a square of four adjacent locations in the inner region. There are four key locations 20 and two pegging regions 22.

System for controlling group access to objects using group access control folder and group identification as individual user

Abstract: A method and system for controlling access by groups of users to multiple objects stored within a data processing system implemented library wherein each object has an access list associated therewith explicitly listing individual users permitted access to that object. A group identification is established which encompasses all users within the data processing system, a selected subset of users with the data processing system, or a single selected user and his or her designated affinity users or proxies. The group identification is then listed within an associated access list for a particular object and upon an attempted access of the particular object by a user not listed explicitly within the associated access list, a determination is made as to whether or not that user is listed within a group identification which is permitted access. In one embodiment of the present invention selected objects and users each have associated therewith a clearance level and access to a selected object by a particular user listed within a group identification may be denied if that particular user's clearance level does not meet or exceed the clearance level of the selected object.

Integration of data between typed objects by mutual, direct invocation between object managers corresponding to object types

Abstract: An object based data processing system including an extensible set of object types and a corresponding set of "object managers" wherein each object manager is a program for operating with the data stored in a corresponding type of object. The object managers in general support at least a standard set of operations. Any program can effect performance of these standard operations on objects of any type by making an "invocation" request. In response to an invocation request, object management services (which are available to all object managers) identifies and invokes an object manager that is suitable for performing the requested operation on the specified type of data. A mechanism is provided for linking data from one object into another object. An object catalog includes both information about objects and about links between objects. Data interchange services are provided for communicating data between objects of different types, using a set of standard data interchange formats. A matchmaker facility permits two processes that are to cooperate in a data interchange operation identify each other and to identify data formats they have in common. A facility is provided for managing shared data "resources". Customized versions of resources can be created and co-exist with standard resources. A resource retrieval function determines whether a customized or a standard resource is to be returned in response to each request for a resource.

Rule Management in Object Oriented Databases: A Uniform Approach

Abstract: Rules have been proposed for providing active behaviour in DBMS. Previous attempts to add rules to Object Oriented DBs have often resulted in a dichotomy between rules and other kind of objects. Bere a uniform approach is presented, in which rules are described and handled in the same way as any other object in the system, without any additional mechanisms being introduced. Thus rules can be related to other objects or arranged in hierarchies, and rules can even be defined which are triggered by methods attached to rules themselves. Since rules and classes are both objects, a relationship between these two kinds of objects can be used to provide a class-based index for rules. In this way, the search for applicable rules is considerably reduced. An early implementation and several examples are shown in ADAM, an Object Oriented DB in PROLOG.

Achieving generalized object recognition through reasoning about association of function to structure

Abstract: An attempt is made to demonstrate the feasibility of defining an object category in terms of the functional properties shared by all objects in the category. This form of representation should allow much greater generality. A complete system has been implemented that takes the boundary surface description of a 3D object as its input and attempts to recognize whether the object belongs to the category 'chair' and, if so, into which subcategory if falls. This is, to the authors' knowledge, the first implemented system to explore the use of a purely function-based definition of an object category (that is, no explicit geometric or structural model) to recognize 3D objects. System competence has been evaluated on a database of over 100 objects, and the results largely agree with human interpretation of the objects. >

On the verification of hypothesized matches in model-based recognition

Abstract: Model-based recognition methods generally use ad hoc techniques to decide whether or not a model of an object matches a given scene. The most common such technique is to set an empirically determined threshold on the fraction of model features that must be matched to data features. Conditions under which to accept a match as correct are rigorously derived. The analysis is based on modeling the recognition process as a statistical occupancy problem. This model makes the assumption that pairings of object and data features can be characterized as a random process with a uniform distribution. The authors present a number of examples illustrating that real image data are well approximated by such a random process. Using a statistical occupancy model, they derive an expression for the probability that a randomly occurring match will account for a given fraction of the features of a particular object. This expression is a function of the number of model features, the number of data features, and bounds on the degree of sensor noise. It provides a means of setting a threshold such that the probability of a random match is very small. >