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Geographical Data Modeling UML and Data Modeling Elements Examples from the Marine Data Model and Ar

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data model = limited representation of reality. a discretization or partitioning of space ... Data Model. Representation of information about a form or a process ... – PowerPoint PPT presentation

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Title: Geographical Data Modeling UML and Data Modeling Elements Examples from the Marine Data Model and Ar


1
Geographical Data Modeling UML and Data
Modeling ElementsExamples from the Marine Data
Model and ArcHydro (Thanks to Dawn Wright)
  • Longley et al., ch. 8

2
Models for GIS
  • representation of reality -- model
  • GIS itself is based on a model of complexity and
    used to model complexity
  • Not a full representation of reality even at 11
  • data model limited representation of reality
  • a discretization or partitioning of space
  • finite, discrete nature of computing devices

3
Data Model
  • Representation of information about a form or a
    process
  • E.g. a weather map with isotherms
  • FIELD grid
  • OBJECT isoline
  • A good model allows us to infer process
  • FIELD or OBJECT geo-relational

4
3 Data Models
  • geo-relational coverage (object view from
    classic ArcInfo polys)
  • geo-relational shapefile (object view from
    ArcView)
  • geodatabase (object-oriented new in ArcGIS 8,9
    etc.)

5
Object Oriented GIS (p. 191)
  • Object a self-contained package of information
    describing an entity
  • Collection of objects class
  • Objects can have behavior encapsulation
  • Inheritance reusable objects
  • Polymorphism-objects can have their own
    implementation for application-e.g. create, draw,
    delete

6
Georelational Data ModelClassic ArcInfo and
ArcView
Arc
Info
command line interface Unix, NT, Windows ArcView
as interface
7
ArcInfo Coverage as a Data Structure
Image courtesy of Louisville/Jefferson County
Information Consortium, Kentucky
8
Data Structure
  • Not tied to process at all
  • Concerned simply with what can be computed and
    what cant
  • Way in which the data model is represented in the
    GIS
  • DEM for grid or layer model (e.g. array)
  • contour for isoline model
  • TIN for Delaunay triangulation model
  • coverages, shapefiles for geo-relational
  • geodatabase for OO geodatabase

9
ArcGIS 9 Icons
10
Geodatabase
  • Features and attributes as objects
  • Relationships among features encoded
  • Validation or editing rules, behaviors
  • Container for
  • Vector, raster, tabular data
  • Relationships
  • Topology

MS-Office
11
Relationships for a feature
12
ArcGIS Data Modelssupport.esri.com/datamodels.cfm
13
ArcMarine dusk.geo.orst.edu/djl/arcgis
14
Data Modeling for Spatial Analysis
  • What is spatial analysis?
  • "a set of methods whose results change when the
    locations of the objects being analyzed change"
  • Methods for working with spatial data
  • to detect patterns, anomalies
  • to find answers to questions
  • to test or confirm theories
  • deductive reasoning-general to specific
  • to generate new theories and generalizations
  • inductive reasoning-specific to general

15
What is Spatial Analysis (cont.)
  • Methods for adding value to data
  • in doing scientific research
  • in trying to convince others
  • A collaboration between human and machine
  • How do we set up the framework for spatial
    analysis?
  • Data model to data structure

16
A Georelational to a Geodatabase Model
  • Coverage and shapefile data structures
  • homogenous collections of points, lines, and
    polygons with generic, 1- and 2-dimensional
    "behavior" as operations
  • Cant distinguish behaviors
  • Point for a marker buoy, same as point for
    observation
  • smart features in a geodatabase
  • lighthouse must be on land, marine mammal siting
    must be in ocean
  • Objects can self-police

17
Purpose of ArcHydro, ArcMarine etc.
  • Basic template for implementing GIS projects
  • input, formatting, geoprocessing, creating maps,
    performing analyses
  • Basic framework for writing program code and
    maintaining applications
  • development of tools for the community
  • Promote networking and data sharing through
    established standards
  • common modelinteroperability

18
ArcMarine Design Strategy
Generic Marine Data Model
Inheritance
User Group Data Model
User Group Data Model
User Group Data Model
19
Geodatabase Concepts
  • ESRI's data object-oriented data model
  • objects, features, behaviors
  • Geodatabase
  • collection of feature data sets, rasters, TINs
  • all data in relational tables
  • behavior is coupled with features through rules
    (object-orientation)
  • Supports model-builder for processes
  • Feature data set
  • contains feature classes
  • defines topological role of features
  • has a coordinate system

20
Geodatabase Concepts ( cont. )
  • Feature class
  • stored in a relational table
  • special field for geometric shape
  • geometric data incorporated into the database
  • Point, multipoint, segment, path, ring, polyline,
    polygon

21
Geodatabase Feature Class Geometries
22
Modeling Process
Conceptual Model Lists, flow diagrams, etc
Real World Objects and relationships
Logical Model Diagram in CASE Tool
Physical Model
Database Schema (Object state)
Graphic courtesy of ESRI
23
Data Model Levels
Reality
Human-oriented
Conceptual Model
Increasing Abstraction
Logical Model
Computer-oriented
Physical Model
24
Specific Steps in Data Modeling
  • (1) Conceptualize the user's view of data
  • what are the basic features needed to solve the
    problem?
  • (2) Select the geographic representation
  • points, lines, areas, rasters, TINs
  • (3) Define objects, features, and relationships
  • draw a UML diagram, specify relationships,
    behaviors
  • (4) Match to geodatabase elements
  • Refine relationships, behaviors
  • (5) Organize geodatabase structure, add data

25
( 1 ) Users View of Data
26
( 1 ) Users View of Data cont.
27
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28
(2)Select geographic rep.
29
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30
Steps in Data Modeling
  • (1) Conceptualize the user's view of data
  • what are the basic features needed to solve the
    problem?
  • (2) Select the geographic representation
  • points, lines, areas, rasters, TINs
  • (3) Define objects and relationships
  • draw a UML diagram, specify relationships,
    behaviors
  • (4) Match to geodatabase elements
  • Refine relationships, behaviors
  • (5) Organize geodatabase structure, add data

31
Unified Modeling Language
  • Entity-relationship diagrams
  • Design the methodologies, diagram notations
  • UML
  • Not a design methodology
  • Just a diagrammatic notation based on methods
  • Endorsed by leading software and database
    companies

32
UML ( cont. )
  • Diagrammatic notation visual language...
  • For constructing a data model
  • Drawings, relationships constructed in Visio
    (other tools available)
  • Tools to input a drawing into ArcGIS
  • input drawing to the data model

33
UML Notation
  • a class is shown as a box
  • top part contains the name of the class
  • lower part contains the attributes
  • methods associated with the class
  • lines connect boxes and indicate relationships

34
Graphic courtesy of Maidment et al., ArcHydro
team
35
UML Notation ( cont. )
  • Abstract class
  • specify subclasses underneath
  • Mammals w/human or dog feature classes
  • no new instances
  • Feature Class
  • Specify subtypes underneath
  • Human, dog, cat

36
Objects and Features
  • Object (real world)
  • in ArcGIS an object is non-spatial
  • it is NOT a point, line, or area
  • it has no geographic location
  • it has no shape attribute in its table
  • Drainage network, ship, vehicle, customer,
    lake, house, etc.
  • Feature (spatial context)
  • an object that has geographic location
  • a point, line, area, TIN, raster

37
Relationships
  • Links between classes, shown as lines
  • One to one
  • One to many
  • Many to many

38
Relationships (cont.)
  • 11 - solid line
  • one record in Class A linked to one record in
    Class B
  • is married to
  • the class of state capitals linked to the class
    of states
  • 1n - solid line with at one end
  • one record in Class A linked to any number of
    records in Class B
  • "owns"
  • the class of states linked to the class of area
    codes

39
Relationships (cont.)
  • mn - solid line with at both ends
  • any number of records in Class A linked to any
    number of records in Class B
  • "has visited
  • "was never married to"
  • the class of mountain lions linked to the class
    of wilderness areas

40
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41
Graphic courtesy of Maidment et al., ArcHydro
team
42
Type Inheritance
  • White triangle
  • Class B inherits the properties (attributes,
    methods) of Class A
  • the class street inherits from the class
    transportation network
  • Solid diamond
  • the parts and the whole depend on each other

43
Graphic courtesy of Maidment et al., ArcHydro
team
44
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45
Steps in Data Modeling
  • (1) Conceptualize the user's view of data
  • what are the basic features needed to solve the
    problem?
  • (2) Select the geographic representation
  • points, lines, areas, rasters, TINs
  • (3) Define objects and relationships
  • draw a UML diagram, specify relationships,
    behaviors
  • (4) Match to geodatabase elements
  • Refine relationships, behaviors
  • (5) Organize geodatabase structure, add data

46
(No Transcript)
47
Steps in Data Modeling
  • (1) Conceptualize the user's view of data
  • what are the basic features needed to solve the
    problem?
  • (2) Select the geographic representation
  • points, lines, areas, rasters, TINs
  • (3) Define objects and relationships
  • draw a UML diagram, specify relationships,
    behaviors
  • (4) Match to geodatabase elements
  • Refine relationships, behaviors
  • (5) Organize geodatabase structure, add data
  • e.g., Marine Data Model tutorial
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