Showing papers on "Object model published in 1991"

Object-oriented modeling and design

Abstract: 1. Introduction. I. MODELING CONCEPTS. 2. Modeling as a Design Technique. 3. Object Modeling. 4. Advanced Object Modeling. 5. Dynamic Modeling. 6. Functional Modeling. II. DESIGN METHODOLOGY. 7. Methodology Preview. 8. Analysis. 9. System Design. 10. Object Design. 11. Methodology Summary. 12. Comparison of Methodologies. III. IMPLEMENTATION. 13. From Design to Implementation. 14. Programming Style. 15. Object-Oriented Languages. 16. Non-Object-Oriented Languages. 17. Databases. 18. Object Diagram Compiler. 19. Computer Animation. 20. Electrical Distribution Design System. 21. Future of Object-Oriented Technology. Appendix A: OMT Graphical Notation. Appendix B: Glossary. Index.

Object modeling by registration of multiple range images

Abstract: The problem of creating a complete model of a physical object is studied. Although this may be possible using intensity images, the authors use range images which directly provide access to three-dimensional information. The first problem that needs to be solved is to find the transformation between the different views. Previous approaches have either assumed this transformation to be known (which is extremely difficult for a complete model) or computed it with feature matching (which is not accurate enough for integration. The authors propose an approach that works on range data directly and registers successive views with enough overlapping area to get an accurate transformation between views. This is performed by minimizing a functional that does not require point-to-point matches. Details are given of the registration method and modeling procedure, and they are illustrated on range images of complex objects. >

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.

CAD-based computer vision: from CAD models to relational graphs

Abstract: The topic of model-building for 3-D objects is examined. Most 3-D object recognition systems construct models either manually or by training. Neither approach has been very satisfactory, particularly in designing object recognition systems which can handle a large number of objects. Recent interest in integrating mechanical CAD systems and vision systems has led to a third type of model building for vision: adaptation of preexisting CAD models of objects for recognition. If a solid model of an object to be recognized is already available in a manufacturing database, then it should be possible to infer automatically a model appropriate for vision tasks from the manufacturing model. Such a system has been developed. It uses 3-D object descriptions created on a commercial CAD system and expressed in both the industry-standard IGES form and a polyhedral approximation and performs geometric inferencing to obtain a relational graph representation of the object which can be stored in a database of models for object recognition. Relational graph models contain both view-independent information extracted from the IGES description and view-dependent information (patch areas) extracted from synthetic views of the object. It is argued that such a system is needed to efficiently create a large database (more than 100 objects) of 3-D models to evaluate matching strategies. >

Segmentation of people in motion

Abstract: A method for segmenting monocular images of people in motion from a cinematic sequence of frames is described. This method is based on image intensities, motion, and an object model-i.e., a model of the image of a person in motion. Though each part of a person may move in different directions at any instant, the time averaged motion of all parts must converge to a global average value over a few seconds. People in an image may be occluded by other people, and usually it is not easy to detect their boundaries. These boundaries can be detected with motion information if they move in different directions, even if there are almost no apparent differences among object intensities or colors. Each image of a person in a scene usually can be divided into several parts, each with distinct intensities or colors. The parts of a person can be merged into a single group by an iterative merging algorithm based on the object model and the motion information because the parts move coherently. This merging is analogous to the property of perceptual grouping in human visual perception of motion. Experiments based on a sequence of complex real scenes produced results that are supportive of the authors approach to the segmentation of people in motion. >

User interface for a relational database using a task object for defining search queries in response to a profile object which describes user proficiency

Abstract: A method and object-oriented architecture for interfacing a user to a relational database system The contour of the interface is defined by a profile object and a task object. The profile object, in response to user selection, defines one of multiple role objects with associated user proficiency and system behavioral characteristics. The task object responds to parameters derived from the profile object to generating a query for the relational database system. In one form, the task object includes one or more functional objects suitable to query the database. Representative functional objects are the domain object (used to formulate problem oriented queries), the analysis object (used to analyze the data extracted from the database), the report object (used to generate a user response format), and the link object (used to relate the components within the task object). The interface according to the invention matches the abilities of the user to the resources of the database system, manipulates problem oriented high-level queries, and provides an object oriented architecture readily amenable to object refinement.

Updating relational databases through object-based views

Abstract: The view-object model provides a formal basis for representing and manipulating object-based views on relational databases. In this paper, we present a scheme for handling update operations on view objects. Because a typical view object encompasses multiple relations, a view-object update request must be translated into valid operations on the underlying relational database. Building on an existing approach to update relational views, we introduce algorithms to enumerate all valid translations of the various update operations on view objects. The process of choosing a translator for view-object update occurs at view-object generation time. Once chosen, the translator can handle any update request on the view object.

Object recognition by a Hopfield neural network

Abstract: A two-dimensional model-based object recognition technique is introduced to identify and locate isolated or overlapping 2-D objects in any position and orientation. A cooperative feature-matching technique is proposed that is implemented by a Hopfield neural network. The proposed matching technique uses the parallelism of the neural network to globally match all the objects in the input scene against all the object models in the model-database at the same time. A global model graph representing all the object models is constructed where each node in the graph represents a feature that has a numerical feature value and is connected to other nodes by an arc representing the relationship or compatibility between them. Object recognition is formulated as matching this global model with an input scene graph representing a single object or several overlapping objects. The performance of the proposed technique is compared with that of a relaxation technique. >

Object/behavior diagrams

Abstract: A novel diagram technique is presented to depict the structure as well as the behavior of objects One of its distinguishing characteristics is its strict adherence to the object-oriented paradigm A first prototype of an editor for object/behavior diagrams has been developed and is running on SUN-workstations To assist the user the editor provides hypertext style facilities for navigating through different diagrams For example, by clicking on an activity in a life cycle diagram one moves to the activity specification diagram of that activity >

A hierarchical multiple-view approach to three-dimensional object recognition

Abstract: A hierarchical approach is proposed for solving the surface and vertex correspondence problems in multiple-view-based 3D object-recognition systems. The proposed scheme is a coarse-to-fine search process, and a Hopfield network is used at each stage. Compared with conventional object-matching schemes, the proposed technique provides a more general and compact formulation of the problem and a solution more suitable for parallel implementation. At the coarse search stage, the surface matching scores between the input image and each object model in the database are computed through a Hopfield network and are used to select the candidates for further consideration. At the fine search stage, the object models selected from the previous stage are fed into another Hopfield network for vertex matching. The object model that has the best surface and vertex correspondences with the input image is finally singled out as the best matched model. Experimental results are reported using both synthetic and real range images to corroborate the proposed theory. >

The combinatorics of heuristic search termination for object recognition in cluttered environments

Abstract: Many current recognition systems terminate a search once an interpretation that is good enough is found. The author formally examines the combinatorics of this approach, showing that choosing correct termination procedures can dramatically reduce the search. In particular, the author provides conditions on the object model and the scene clutter such that the expected search is at most quartic. The analytic results are shown to be in agreement with empirical data for cluttered object recognition. These results imply that it is critical to use techniques that select subsets of the data likely to have come from a single object before establishing a correspondence between data and model features. >

Effective clustering of complex objects in object-oriented databases

Abstract: Clustering is an effective mechanism for retrieving complex objects. Many object-oriented database management systems have suggested variant clustering schemes to improve their performance. Two issues may compromise the effectiveness of a clustered structure , i.e., object updates and multiple relationships. Updates may destroy the initially cIustered structure, and in a multiple relationship environment, clustering objects based on one relationship may sacrifice others. This paper investigates the updating effects and suggests a dynamic reclustering scheme to reorganize related objects on the disk. A cost model is introduced to estimate the benefit and overhead of reclustering. Reorganizations are performed only when the overhead can be justified. For environments in which multiple relationships among objects exist, the paper proposes a leveled clustering scheme to order related objects into a clustering sequence. Our simulation results show that the leveled clustering scheme has a better access time compared with a single-level clustering scheme.

The muse object architecture: a new operating system structuring concept

Abstract: A next generation operating system should accommodate an ultra large-scale, open, self-advancing, and distributed environment. This environment is dynamic and versatile in nature. In it, an unlimited number of objects, ranging from fine to coarse-grained, are emerging, vanishing, evolving, and being replaced; computers of various processing capacities are dynamically connected and disconnected to networks; systems can optimize object execution by automatically detecting the user's and/or programmer's requirements. In this paper, we investigate several structuring concepts in existing operating systems. These structuring concepts include layered structuring, hierarchical structuring, policy/mechanism separation, collective kernel structuring, object-based structuring, open operating system structuring, virtual machine structuring, and proxy structuring.We adjudge that these structuring concepts are not sufficient to support the environment described above because they lack the abilities to handle dynamic system behavior and transparency and to control dependency. Thus, we propose a new operating system structuring concept which we call the Muse object architecture. In this architecture, an object is a single abstraction of a computing resource in the system. Each object has a group of meta-objects which provide an execution environment. These meta-objects constitute a meta-space which is represented within the meta-hierarchy. An object is causally connected with its meta-objects: the internal structure of an object is represented by meta-objects; an object can make a request of meta-computing; a meta-object can reflect the results of meta-computing to its object. We discuss object/meta-object separation, the meta-hierarchy, and reflective computing of the architecture. We then compare the Muse object architecture with the existing structuring concepts.We also demonstrate that the Muse object architecture is suitable for structuring future operating systems by presenting several system services of the Muse operating system such as class systems, a real-time scheduler with hierarchical policies, and free-grained objects management. Class systems facilitate programming by several classes of programming languages. A real-time scheduler with hierarchical policies can meet various types of real-time constraints presented by applications. Free-grained objects management can suit the object granularity to the application, so that an object is efficiently managed according to its granularity. Finally, we present the implementation of the Muse operating system which is designed based on the Muse object architecture. Version 0.3 of the Muse kernel is running on the MC68030 based Sony NEWS workstations.

Mixed-resolution, N-dimensional object space method and apparatus

Abstract: Object spaces which mechanize higher order relationships between attributes which describe a particular problem domain. An abstract object description defined by a set of attributes and their corresponding values is transformed into a mixed-resolution, N-dimensional object space. The mixed-resolution, N-dimensional object space represents a mechanized, logically encoded expression of attribute relationships that can be visualized. The method and apparatus interleave the frame to generate an object descriptor and generate from the frame and the object descriptor, encoded names of spatial locations for each of the N dimensions of the mixed-resolution, N-dimensional, object space, conforming to a primary form of a reflected binary code. A virtual image of the N-dimensional, object space is generated from the dimensional-spatial locations and resolution-spatial locations, and attribute values corresponding to a region of the virtual image may be selected for display.

Function materialization in object bases

Abstract: We describe funct$on materzakation as an optimization concept in object-oriented databases. Exploiting the object-oriented paradigm—namely class lficatton, object identzty, and encapsalatzon-—facilitates a rather easy incorporation of function materialization mto (existing) object-oriented systems. Furthermore, the exploitation of encapsulation (information hiding) and object identity provides for additional performance tuning measures which drastically decrease the rematerialization overhead incurred by updates in the object base. The paper concludes with a quantitative analysis of function materialization based on a sample performance benchmark obtained from our experimental object base system GOM.

Semantic Modeling of Object Oriented Databases

Abstract: This paper describes a design methodology for an object oriented database, based on a semantic network This approach is based on the assumption that Yemantic data models are more powerful and more easy to use than current proposed object oriented data models They are especially more poweful in representing integrity constraints and various relationships, Object oriented data models are generally based only on class hierarchies and inheritance, plus their ability to represent the behavior of objects, But this latter capability is generally provided through an algorithmic language which cannot be considered as a conceptual language This paper describes a design procedure which generates an object oriented database schema (both the structural aspect and the dynamic aspect) from an abstract specification giveri in a high level language This specification language is built upon a semantic network and allows to define integrity constraints and behavior rules This approach is presented through a CASE tool environment

Virtual object management system for managing virtual objects which correspond to real objects under a user defined hierarchy

Abstract: An object management system is equipped with a single real object management system for managing a real file object such as data and a program based on a real directory object in a hierarchical structure, and also at least a single virtual object management system for managing a virtual file object corresponding to said file object based upon a virtual directory object which is independent of the directory object in a hierarchical structure.

Using an object-oriented diagram technique for the design of information systems

Abstract: An object-oriented diagram technique is introduced for the design of information systems. Structural properties of objects are depicted in object diagrams. Dynamic properties are shown in behaviour diagrams. Object diagrams are based on semantic data model concepts. Behaviour diagrams are based on Petri nets and model the life cycles of objects through a set of states (places) and activities (transitions). The relationship between Object/Behaviour diagrams and Predicate/Transition nets is shown. The semantics of Object/Behaviour diagrams is formally defined through a mapping into Predicate/Transition nets.

Interoperability and object identity

Abstract: Data model transparency can be achieved by providing a canonical language format for the definition and seamless manipulation of multiple autonomous information bases In this paper we assume a canonical data and computational model combining the function and object-oriented paradigmsWe investigate the concept of identity as a property of an object and the various ways this property is supported in existing databases, in relation to the object-oriented canonical data modelThe canonical data model is the tool for combining and integrating preexisting syntactical homogeneous, but semantical heterogeneous data types into generalized unifying data types We identify requirements for object identity in federated systems, and discuss problems of object identity and semantical object replication arising from this new abstraction level We argue that a strong notion of identity at the federated level can only be acheived by weakening strict autonomy requirements of the component information bases Finally we discuss various solutions to this problem that differ in their requirements with repect to giving up autonomy

Object Integrity Using Rules

Abstract: Integrity maintenance in object-oriented systems has so far received little attention. This paper is an attempt to fill this gap. It describes a mechanism for maintaining integrity in an object-oriented database, implemented for the O2 system, and which uses the production rule approach to constraint maintenance. Object integrity is ensured by objects themselves — the rules which are activated when selected events take place. The approach presented is original, in the sense that it takes full advantage of the object-oriented paradigm, considering constraints as first-class citizens which can be inherited, and defined independently of any application. Furthermore, we support maintenance of not only static but also some types of dynamic constraints, as well as constraints on object behavior.

An evaluation framework for algebraic object-oriented query models

Abstract: An evaluation framework consisting of five categories of criteria is developed for evaluating the relative merits of objects algebras, namely, object-orientedness, expressiveness, formalness, performance and database issues. Four recently proposed object algebras are evaluated against these criteria. It is shown that there exists no object algebra that satisfies all the criteria. It is argued that, since some of the criteria may not be compatible, a feasible object algebra has to make some tradeoffs to suit domain-specific needs. It is possible to identify a minimal subset of the criteria. The criterion that an object algebra should support encapsulation seems to be the most important. If an object algebra fails to support this criterion, its semantics is inconsistent with the concept of 'data abstraction', which makes a language object-oriented. >

Generic recognition through qualitative reasoning about 3-D shape and object function

Abstract: The work which demonstrates the feasibility of a different approach to 3-D object recognition is described. The authors construct a definition of a generic object category, such as a chair, in terms of the function required of the object. This definition is based on qualitative reasoning about 3-D shape, and does not imply any particular geometric or structural model for an object. Thus, this approach has the potential to lead to recognition systems of much greater generality than current CAD-based or model-based approaches. >

Semantic enrichment of database schemes: an object oriented approach

Abstract: When a database is to be interoperated with others, its scheme must first be converted to the canonical model of the federated system. This implies a knowledge acquisition process to upgrade the semantic level of the scheme. The authors present a methodology to convert relational schemas to a semantically rich object oriented model. It is based on inclusion dependencies, but also takes into account exclusion and complementariness dependencies. >

The OO-Binary relationship model: a truly object oriented conceptual model

Abstract: Conventional conceptual models like the Binary Relationship Model (also known as NIAM) or the Entity-Relationship Model do not fit well with the promising object oriented database systems. In this paper we show that is possible to turn such a conventional conceptual model (in particular the Binary Relationship Model) into a truly object oriented conceptual model which combines the assets of the conventional model with the advantages of the object oriented approach.

Recognizing and locating a known object from multiple images

Abstract: An approach to recognizing and locating a partially visible object from multiple images for a pile of parts is proposed. The image-to-model correspondence is established through an examination of the consistency between the surface patches extracted from the images and the patches described in an object model. To obtain the scene description, which is composed of parameterized surface patches, the scene's needle map is derived by a modified photometric stereo method. The needle map is then segmented into primitive surfaces, and the resultant patches are identified and described by using a modified Hough transformation based on the Gaussian spherical maps of the patches. To interpret the scene description, the object model is built with a frame structure to describe geometric features of the model patches. By a search process guided by some heuristic planning strategies based on the fuzzy-set concept, sets of patches considered to be possibly on the surface of the model object are extracted from the scene description. The candidate sets are tested and the locations and orientations of the corresponding object instances are computed. Results of two experiments are reported. >

Robot vision using a feature search strategy generated from a 3D object model

Abstract: A robot vision system that automatically generates an object recognition strategy from a 3D model and recognizes the object using this strategy is presented. The appearance of an object from various viewpoints is described in terms of visible 2D features such as parallel lines and ellipses. Features are then ranked according to the number of viewpoints from which they are visible. The rank and feature extraction cost of each feature are used to generate a treelike strategy graph. This graph gives an efficient feature search order when the viewpoint is unknown, starting with commonly occurring features and ending with features specific to a certain viewpoint. The system searches for features in the order indicated by the graph. After detection, the system compares a lines representation generated from the 3D model with the image features to localize the object. Perspective projection is used in the localization process to obtain the precise position and attitude of the object, whereas orthographic projection is used in the strategy generation process to allow symbolic manipulation. Experimental results are given. >