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Multidimensional Representation of Geographic Features. E. Lynn Usery Research Geographer U.S. Geological Survey. Outline. Introduction Objectives Background Approach Theoretical Basis Implementation Strategy Application – DLG-F usage Conclusions. Introduction.

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multidimensional representation of geographic features

Multidimensional Representation of Geographic Features

E. Lynn Usery

Research Geographer

U.S. Geological Survey

ISPRS Congress 2000

outline
Outline
  • Introduction
  • Objectives
  • Background
  • Approach
    • Theoretical Basis
    • Implementation Strategy
  • Application – DLG-F usage
  • Conclusions

ISPRS Congress 2000

introduction
Introduction
  • Need for geoinformation theory
    • UCGIS Research Priority on “Geographic Representation”; proposed theme on ontology.
    • Need to handle 3 dimensions and time
    • Need to interface to geographic process models
      • Climate models
      • Growth models
      • Biologic models
      • Watershed/water quality models

ISPRS Congress 2000

introduction1
Introduction
  • Geographic reality consists of entities and processes
  • We represent entities as objects and processes as models
    • Mathematical (process)
    • Data driven (map, spatial, or GIS)
    • Combinations

ISPRS Congress 2000

objectives
Objectives
  • Advance development of theory of geographic information supporting multiple representations.
  • Validate theory in multiple applications.
  • Develop implementation around specific application for feasibility testing.
  • Use current GIScience knowledge as base from which to extend representation ideas.

ISPRS Congress 2000

background
Background
  • Significant work toward a theory
    • Peuquet, 1988; Molenaar, 1991; Mark, 1993; Usery, 1996; Frank, 1998.
    • Geography
      • Place, attribute, time as fundamental basis for spatial analysis from Berry (1964), basis of current GIS
      • Region theory
    • Cartography
      • Abstraction and generalization concepts

ISPRS Congress 2000

background1
Background
  • Cognitive psychology
    • Basic level of categorization exists
    • For geography, that level is geographic entities or features
      • Roads
      • Streams
      • Buildings
      • Watersheds

ISPRS Congress 2000

problems
Problems
  • How to advance theory of geoinformation?
  • Limits of commercial GIS software systems
    • Map model of reality
    • Geometry (raster or vector) based objects with attached attributes
  • Needs to advance
    • ,,Z,t or X,Y,Z,t coordinates for entities
    • Motion and process

ISPRS Congress 2000

feature approach
Feature Approach
  • Feature is geographic entity and object representation
  • One feature, many objects
    • Multiple resolutions
    • Multiple geometries
    • Access from single identity

ISPRS Congress 2000

slide10

Definitions

ISPRS Congress 2000

requirements to move from theoretical concepts to implementation
Requirements to Move from Theoretical Concepts to Implementation
  • Theory of sufficient completeness to support application needs
  • Transition framework from theoretical concepts to a data model
  • Implementation methodology from the data model

ISPRS Congress 2000

theoretical completeness
Theoretical Completeness
  • Components of theory available
    • Feature concepts
    • Human understanding
      • Category theory
      • Metaphor
      • Algebraic formalisms
  • Missing links
    • Feature to feature relations
      • Some work on topological relations
    • Thematic, temporal relations

ISPRS Congress 2000

transition framework
Transition Framework
  • Dimensions
  • Concepts
  • Data Models
  • Data Structures

ISPRS Congress 2000

implementation methodology
Implementation Methodology
  • Feature processing system
    • Create, select, manipulate, analyze features
    • Use existing databases
      • Spatial, thematic, temporal attributes and relationships
      • Vector geometry (,,Z,t lists)
      • Raster geometry (pixel matrices)
    • Heuristics, procedures, models

ISPRS Congress 2000

application of the framework
Application of the Framework
  • Watershed/water quality modeling application
  • Test site in Little River, Georgia, USA
    • 340 sq. km.
    • Traditional data layers
      • Soils, land cover, elevation, precipitation
    • Derived information
      • Slope, aspect, flow directions, flow paths, flow planes
    • Multiple geometries and resolutions
      • Vector
      • Raster at 3, 30, 60, 120, 210, 240, 480, 960, 1920 m cells

ISPRS Congress 2000

implementation of watershed features
Implementation of Watershed Features
  • Use USGS DLG-F structures
  • Apply to raster geometry
  • Build attributes and relations specific to defined features
  • Develop parameters for water models

ISPRS Congress 2000

conclusions
Conclusions
  • Conceptual framework (addition to theory) supporting multiple geometries and multidimensional representation developed.
  • Geographic feature is unique entity;basis of theory
    • Feature has multiple object representations
  • Transition framework from concepts to data model developed
  • Data model to data structure transition developed

ISPRS Congress 2000

conclusions1
Conclusions
  • Framework being implemented for watershed/water quality modeling
  • Features developed
  • Data structures for features developed from USGS DLG-F and are being implemented against raster geometry.

ISPRS Congress 2000

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