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54
Status of land cover classification accuracy assessment”, Remote Sensing of Environment
"... The production of thematic maps, such as those depicting land cover, using an image classification is one of the most common applications of remote sensing. Considerable research has been directed at the various components of the mapping process, including the assessment of accuracy. This paper brie ..."
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Cited by 199 (2 self)
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The production of thematic maps, such as those depicting land cover, using an image classification is one of the most common applications of remote sensing. Considerable research has been directed at the various components of the mapping process, including the assessment of accuracy. This paper briefly reviews the background and methods of classification accuracy assessment that are commonly used and recommended in the research literature. It is, however, evident that the research community does not universally adopt the approaches that are often recommended to it, perhaps a reflection of the problems associated with accuracy assessment, and typically fails to achieve the accuracy targets commonly specified. The community often tends to use, unquestioningly, techniques based on the confusion matrix for which the correct application and interpretation requires the satisfaction of often untenable assumptions (e.g., perfect coregistration of data sets) and the provision of rarely conveyed information (e.g., sampling design for ground data acquisition). Eight broad problem areas that currently limit the ability to appropriately assess, document, and use the accuracy of thematic maps derived from remote sensing are explored. The implications of these problems are that it is unlikely that a single standardized method of accuracy assessment and reporting can be identified, but some possible directions for future research that may facilitate accuracy assessment are highlighted. D 2002 Elsevier Science Inc. All rights reserved. 1.
Boolean Connection Algebras: A New Approach to the RegionConnection Calculus
 Artificial Intelligence
, 1999
"... The RegionConnection Calculus (RCC) is a well established formal system for qualitative spatial reasoning. It provides an axiomatization of space which takes regions as primitive, rather than as constructions from sets of points. The paper introduces boolean connection algebras (BCAs), and prove ..."
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Cited by 47 (7 self)
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The RegionConnection Calculus (RCC) is a well established formal system for qualitative spatial reasoning. It provides an axiomatization of space which takes regions as primitive, rather than as constructions from sets of points. The paper introduces boolean connection algebras (BCAs), and proves that these structures are equivalent to models of the RCC axioms. BCAs permit a wealth of results from the theory of lattices and boolean algebras to be applied to RCC. This is demonstrated by two theorems which provide constructions for BCAs from suitable distributive lattices. It is already well known that regular connected topological spaces yield models of RCC, but the theorems in this paper substantially generalize this result. Additionally, the lattice theoretic techniques used provide the first proof of this result which does not depend on the existence of points in regions. Keywords: RegionConnection Calculus, Qualitative Spatial Reasoning, Boolean Connection Algebra, Mer...
Computation With Imprecise Geospatial Data
, 1998
"... Imprecision in spatial data arises from the granularity or resolution at which observations of phenomena are made, and from the limitations imposed by computational representations, processing and presentational media. Precision is an important component of spatial data quality, and a key to appropr ..."
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Cited by 35 (7 self)
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Imprecision in spatial data arises from the granularity or resolution at which observations of phenomena are made, and from the limitations imposed by computational representations, processing and presentational media. Precision is an important component of spatial data quality, and a key to appropriate integration of collections of data sets. Previous work of the author provides a theoretical foundation for imprecision of spatial data resulting from finite granularities, and gives the beginnings of an approach to reasoning with such data using methods similar to rough set theory. This paper develops the theory further, and extends the work to a model that includes both spatial and semantic components. Notions such as observation, schema, frame of discernment and vagueness are examined and formalised. Keywords: GIS, imprecision, vagueness, resolution, spatial reasoning, data quality, uncertainty. Computers, Environment and Urban Systems 2 1. INTRODUCTION We now live in a world of ...
A Formal Model of the Process of Wayfinding in Built Environments
 In C. Freksa & D.M. Mark (Eds.), Spatial
, 1999
"... . Previous recent research on human wayfinding has focused primarily on mental representations rather than processes of wayfinding. This paper presents a formal model of some aspects of the process of wayfinding, where appropriate elements of human perception and cognition are formally realized ..."
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Cited by 34 (5 self)
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. Previous recent research on human wayfinding has focused primarily on mental representations rather than processes of wayfinding. This paper presents a formal model of some aspects of the process of wayfinding, where appropriate elements of human perception and cognition are formally realized using image schemata and affordances. The goaldriven reasoning chain that leads to action begins with incomplete and imprecise knowledge derived from imperfect observations of space. Actions result in further observations, derived knowledge and, recursively, further actions, until the goal is achieved or the wayfinder gives up. This paper gives a formalization of this process, using a modal extension to classical propositional logic to represent incomplete knowledge. Both knowledge and action are represented through a wayfinding graph. A special case of wayfinding in a building, that is finding one's way through an airport, is used to demonstrate the formal model. Keywords. Wayfind...
Stratified Map Spaces: A Formal Basis for Multiresolution Spatial Databases
 SDH'98 Proceedings 8th International Symposium on Spatial Data Handling, pages 180189. International Geographical
, 1998
"... Precision is a key component of spatial data quality and in this era of globally distributed spatial data it is essential to be able to integrate multiple distributed data sets with heterogeneous levels of precision. Imprecision arises through limitations on semantic and geometric resolution of data ..."
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Cited by 27 (9 self)
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Precision is a key component of spatial data quality and in this era of globally distributed spatial data it is essential to be able to integrate multiple distributed data sets with heterogeneous levels of precision. Imprecision arises through limitations on semantic and geometric resolution of data representations. Generalization, and in particular modeloriented generalization, is an important process in this context, because it enables translation between different levels of precision. This paper provides a formal approach to multiresolution in spatial data handling. It begins by motivating the work and pointing to some of the background research, and then introduces the basic concepts underlying the approach, focusing on the new concept of a stratified map space. The approach is quite general, and to show its application, the paper uses it to provide a formal foundation for generalization and vague regions. Keywords: resolution, generalization, vagueness, theory 1. Introduction W...
Generalizing Graphs using Amalgamation and Selection
 Advances in Spatial Databases. 6th International Symposium, SSD'99, volume 1651 of Lecture Notes in Computer Science
, 1999
"... . This work is a contribution to the developing literature on multiresolution data models. It considers operations for modeloriented generalization in the case where the underlying data is structured as a graph. The paper presents a new approach in that a distinction is made between generalization ..."
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Cited by 26 (6 self)
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. This work is a contribution to the developing literature on multiresolution data models. It considers operations for modeloriented generalization in the case where the underlying data is structured as a graph. The paper presents a new approach in that a distinction is made between generalizations that amalgamate data objects and those that select data objects. We show that these two types of generalization are conceptually distinct, and provide a formal framework in which both can be understood. Generalizations that are combinations of amalgamation and selection are termed simplifications, and the paper provides a formal framework in which simplifications can be computed (for example, as compositions of other simplifications). A detailed case study is presented to illustrate the techniques developed, and directions for further work are discussed. 1 Introduction Specialist spatial information systems (SIS) play an increasingly important role within the Information Tech...
A Formal Approach to Imperfection in Geographic Information
 Computers, Environment and Urban Systems
, 2001
"... Traditional computational models of geographic phenomena offer no room for imperfection. Underlying this tradition is the simplifying assumption that reality is certain, crisp, unambiguous, independent of context, and capable of quantitative representation. This paper reports on initial work which e ..."
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Cited by 26 (4 self)
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Traditional computational models of geographic phenomena offer no room for imperfection. Underlying this tradition is the simplifying assumption that reality is certain, crisp, unambiguous, independent of context, and capable of quantitative representation. This paper reports on initial work which explicitly recognises that most geographic information is intrinsically imperfect. Based on an ontology of imperfection the paper explores a formal model of imperfect geographic information using multivalued logic. The development of Java software able to assist with a geodemographic retail site assessment application is used to illustrate the utility of a formal approach.
A Design of Topological Predicates for Complex Crisp and Fuzzy Regions
 Int. Conf. on Conceptual Modeling
, 2001
"... For a long time topological predicates between spatial objects have been a main area of research on spatial data handling, reasoning, and query languages. But these predicates still suffer from two main restrictions: first, they are only applicable to simplified abstractions of spatial objects l ..."
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Cited by 18 (8 self)
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For a long time topological predicates between spatial objects have been a main area of research on spatial data handling, reasoning, and query languages. But these predicates still suffer from two main restrictions: first, they are only applicable to simplified abstractions of spatial objects like single points, continuous lines, and simple regions, as they occur in systems like current geographical information systems and spatial database systems. Since these abstractions are usually not sufficient to cope with the complexity of geographic reality, their generalization is needed which especially has influence on the nature and definition of their topological relationships. This paper gives a formal definition of complex crisp regions, which may consist of several components and which may have holes, and it especially shows how topological predicates can be defined on them. Second, topological predicates so far only operate on crisp but not on fuzzy spatial objects which occur frequently in geographical reality. Based on complex crisp regions, this paper gives a definition of their fuzzy counterparts and shows how topological predicates can be defined on them. 1
Capturing Fuzziness and Uncertainty of Spatiotemporal Objects
 In ADBIS
, 2001
"... For the majority of spatiotemporal applications, we assume that the modeled world is precise and bound. This simplification seems unnecessary crude for many environments handling spatial and temporal extents, such as navigational applications. In this work, we explore fuzziness and uncertainty, ..."
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Cited by 14 (2 self)
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For the majority of spatiotemporal applications, we assume that the modeled world is precise and bound. This simplification seems unnecessary crude for many environments handling spatial and temporal extents, such as navigational applications. In this work, we explore fuzziness and uncertainty, which we subsume under the term indeterminacy, in the spatiotemporal context.
Granulation for Graphs
 Spatial Information Theory. Cognitive and Computational Foundations of Geographic Information Science. International Conference COSIT'99, volume 1661 of Lecture Notes in Computer Science
, 1999
"... . In multiresolution data handling, a less detailed structure is often derived from a more detailed one by amalgamating elements which are indistinguishable at the lower level of detail. This gathering together of indistinguishable elements is called a granulation of the more detailed structure ..."
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Cited by 12 (6 self)
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. In multiresolution data handling, a less detailed structure is often derived from a more detailed one by amalgamating elements which are indistinguishable at the lower level of detail. This gathering together of indistinguishable elements is called a granulation of the more detailed structure. When handling spatial data at several levels of detail the granulation of graphs is an important topic. The importance of graphs arises from their widespread use in modelling networks, and also from the use of dual graphs of spatial partitions. This paper demonstrates that there are several quite different kinds of granulation for graphs. Four kinds are described in detail, and situations where some of these may arise in spatial information systems are indicated. One particular kind of granulation leads to a new formulation of the boundarysensitive approach to qualitative location developed by Bittner and Stell. Vague graphs and their connection with granulation are also discusse...