Terence R. Smith

A conceptual model and empirical analysis of children's acquisition of spatial knowledge

Abstract How adults and children come to understand, represent and behave within their spatial environment are topics of great interest to geographers, psychologists, environmental planners and laypeople. Considerable research and theory has been published on these and related topics. In this paper, we will review some of what is known and theorized about spatial cognition and then consider elements of our research program on the acquisition of spatial knowledge. We focus on two intimately related topics. The first is the development of a conceptual model of the knowledge structures and processes associated with acquiring, representing and accessing knowledge of a given environment. The conceptual model forms the basis for a formal computational process model intended as a simulation of actual knowledge and performance in way finding tasks. The second emphasis is an in-depth case study of the acquisition of spatial knowledge. The case study focuses on a single child acquiring knowledge of a lengthy route through an unfamiliar suburban neighborhood. It is presented as an empirical test of certain assumptions embodied within the conceptual model. Before introducing the conceptual model and the case study, we first review the state of current theory and data on spatial cognition and identify four central issues confronting researchers in this field. This review provides a necessary context for describing and evaluating our program of research. The second section of this paper discusses elements of the conceptual model and its relationship to other formal computational models. The third section considers specific hypotheses about the acquisition and representation of spatial knowledge and tests of these hypotheses from the single in-depth case study. The final discussion section of this paper is a reconsideration of the four issues raised in the first section and necessary and proposed extensions of the current research.

A digital library for geographically referenced materials

Presently, maps, aerial photos, and other material referenced in geographic terms, such as by the names of communities that appear in the material, are largely inaccessible. Much of the information is only on paper or film, and can be found only in major research libraries. There is a need to make such material more widely available. The goal of the Alexandria Project, which is based at the University of California at Santa Barbara, is to build a distributed digital library for geographically referenced material from throughout the world. The Alexandria Digital Library is scheduled to be made available to the public in July 1996. At that time, Internet users will be able to access and extract information from the ADLs large collection. To accomplish its goal, ADL will provide user interfaces and on-line catalogs that support the formulation and evaluation of geographically constrained queries.

Knowledge about hand shaping and knowledge about objects

Our two experiments investigated associations between cognitive representations of objects and hand-shape categories. Hand configurations were partitioned according to prehensility and the size of the contacting surface, resulting in the classes: pinch, poke, palm, and clench. Experiment 1 elicited object names in response to configuration-name cues, provided ratings of the relevance of each configuration to a set of objects, and probed for the functions determining such relevance. Cueing with a configuration class elicited an associated object category with substantial intersubject agreement, and vice versa. Both the object categories and the functions associated with the four hand-configuration classes differed substantially, although the same object could be associated to some extent with multiple configurations, given variations in function. Experiment 2 elicited the names of hand-configuration classes in response to unfamiliar forms, which varied systematically in depth and the size of the projecting picture-plane surface. The modal response, response time, and degree of intersubject agreement were directly related to these variables. These structural variables, however, did not adequately predict shaping responses to real objects, as ascertained from Experiment 1. The results have implications for cognitive representation of motor categories and hand shaping in response to objects.

Navigator: A psychologically based model of environmental learning through navigation

Abstract This paper describes an implementation of a computational process model of spatial learning. The model is designed to represent basic components of human information processing, as identified by contemporary psychological research and theory. The model comprises two modules, representing an objective view of a suburban environment and a cognitive view of the environment, together with the associated cognitive processes relating to spatial learning and navigation. The second module is based upon information-processing assumptions that relate, for example, to multiple sites of storage, filtering and selection, sensitivity to the importance of environmental features, and forgetting. The implications of the model concerning the processing stages that limit spatial learning, the incremental nature of learning, and the effects of both individual and environmental variation are tested in a series of simulations. By this means the model is of value in tracing out how the architecture of human information processing, in a broad sense, might limit and control the extraction and use of environmental information. More specific model-based predictions are also considered.

Requirements and principles for the implementation and construction of large-scale geographic information systems

Abstract This paper provides a brief survey of the history, structure and functions of ‘traditional’ geographic information systems (GIS), and then suggests a set of requirements that large-scale GIS should satisfy, together with a set of principles for their satisfaction. These principles, which include the systematic application of techniques from several sub-fields of computer science to the design and implementation of GIS and the integration of techniques from computer vision and image processing into standard GIS technology, are discussed in some detail. In particular, the paper provides a detailed discussion of questions relating to appropriate data models, data structures and computational procedures for the efficient storage, retrieval and analysis of spatially-indexed data.

Alexandria digital library: user evaluation studies and system design

The Alexandria Digital Library (ADL) is one of the six digital library projects funded by NSF, DARPA, and NASA. ADLs collection and services focus on information containing georeferences: maps, images, data sets, text, and other information sources with links to geographic locations. During this study period, three different user interfaces were developed and tested by user groups. User feedback was collected through various formal and informal approaches and the results fed back into the design and implementation cycle. This article describes the evolution of the ADL system and the effect of user evaluation on that evolution. ADL is an ongoing project; user feedback and evaluation plans for the remainder of the project are described.

Alexandria Digital Library

The goal of the Alexandria Digital Library Project is to develop a distributed system that provides a comprehensive range of library services for collections of spatially indexed and graphical information. While such collections include digitized maps and images as important special components, the Alexandria Digital Library will involve a very wide range of graphical materials and will include textual materials. Users of the Alexandria Digital Library will range from school children to academic researchers to members of the general public. They will be able to retrieve materials from the library on the basis of information content as well by reference to spatial location.

KBGIS-II A knowledge-based geographical information system

Abstract This paper describes the architecture and working of a recently implemented knowledge-based GIS (KBGIS-II) that was designed to satisfy several general criteria for GIS. The system has four major functions, query-answering, learning, editing and training. The main query finds constrained locations for spatial objects that are describable in a predicate-calculus based spatial object language. The main search procedures include a family of constraint-satisfaction procedures that use a spatial object knowledge base to search efficiently for complex spatial objects in large, multi-layered spatial data bases. These data bases are represented in quadtree form. The search strategy is designed to reduce the computational cost of search in the average case. The learning capabilities of the system include the addition of new locations of complex spatial objects to the knowledge base as queries are answered, and the ability to learn inductively definitions of new spatial objects from examples. The new defin...

Efficient retrieval for browsing large image databases

The management of large image databases poses several interesting and challenging problems. These problems range from ingesting the data and extracting meta-data to the efficient storage and retrieval of the data. Of particular interest are the retrieval methods and user interactions with an image database during browsing. In image databases, the response to a given query is not an exact well-defined set, rather, the user poses a query and expects a set of responses that should contain many possible candidates from which the user chooses the answer set. We first present the browsing model in Alexandria, a digital library for maps and satellite images. Designed for content-based retrieval, the relevant information in an image is encoded in the form of a multi-% dimensional feature vector. Various techniques have been previously proposed for the efficient retrieval of such vectors by reducing the dimensionality of such vectors. We show that for even moderately large databases (in fact, only 1856 texture images), these approaches do not scale well for exact retrieval. However, as a browsing tool, these dimensionality reduction techniques hold much promise.

Scalability issues for high performance digital libraries on the World Wide Web

We investigate scalability issues involved in developing high performance digital library systems. Our observations and solutions are based on our experience with the Alexandria Digital Library (ADL) testbed under development at UCSB. The current ADL system provides online browsing and processing of digitized maps and other geospatially mapped data via the World Wide Web (WWW). A primary activity of the ADL system involves computation and disk I/O for accessing compressed multi resolution images with hierarchical data structures, as well as other duties such as supporting database queries and on the fly HTML page generation. Providing multi resolution image browsing services can reduce network traffic but impose some additional cost at the server. We discuss the necessity of having a multiprocessor DL server to match potentially huge demands in simultaneous access requests from the Internet. We have developed a distributed scheduling system for processing DL requests, which actively monitors the usages of CPU, I/O channels and the interconnection network to effectively distribute work across processing units to exploit task and I/O parallelism. We present an experimental study on the performance of our scheme in addressing the scalability issues arising in ADL wavelet processing and file retrieval. Our results indicate that the system delivers good performance on these types of tasks.