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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


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 Implementation

  • 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 Implementation

  • Dimensions

  • Concepts

  • Data Models

  • Data Structures

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ISPRS Congress 2000 Implementation


Implementation methodology
Implementation Methodology Implementation

  • 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


ISPRS Congress 2000 Implementation


Application of the framework
Application of the Framework Implementation

  • 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


ISPRS Congress 2000 Implementation


ISPRS Congress 2000 Implementation


ISPRS Congress 2000 Implementation


ISPRS Congress 2000 Implementation


ISPRS Congress 2000 Implementation


ISPRS Congress 2000 Implementation


Implementation of watershed features
Implementation of Watershed Features Implementation

  • 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


ISPRS Congress 2000 Implementation


ISPRS Congress 2000 Implementation


ISPRS Congress 2000 Implementation


ISPRS Congress 2000 Implementation


ISPRS Congress 2000 Implementation


ISPRS Congress 2000 Implementation


ISPRS Congress 2000 Implementation


ISPRS Congress 2000 Implementation


ISPRS Congress 2000 Implementation


Conclusions
Conclusions Implementation

  • 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 Implementation

  • 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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