Introduction to Data Models
and Geodatabases
Steve Grisé
Pre Conference Seminars
1
Geodatabases
• More closely represent real world objects than previous GIS data
models
• Provide a starting point for more sophisticated data models based
on a more natural approach
• Rely on geography and rules to define relationships, not just
primary and foreign keys
• Users and Programmers don’t need to manage atomic data
elements/topology, they manage the objects and relationships
instead
Feature
RoadSegment
RoadSegID
FullStreetName
RoadClassification
...
Pre Conference Seminar
2
Inside the Geodatabase
Feature dataset
Tables, subtypes
Feature classes, subtypes
Polygon
Polygon
Route
Line
Line
Annotation
Point
Points
Dimension
Annotation
Attributes
Representations
Raster datasets
Terrain datasets
Relationship classes
Network datasets
Geometric networks
Validation rules
Topology
Default values
Attribute domains
Split/Merge policy
Connectivity rules
Relationship rules
Topology rules
Pre Conference Seminar
3
Geodatabase Options
• ArcGIS Server includes ArcSDE
• Workgroup Geodatabases
– SQL Express
• File Geodatabase
ArcGIS
Simple
ArcSDE
– Fast
– Cross Platform
• Personal Geodatabase
Enterprise
GDB
– MS Access
– SQL Express
Workgroup
GDB
Personal
GDB
File
GDB
Embedded
Database Engine
Pre Conference Seminar
4
Geodatabase Datasets
Surveys
Networks
Addresses
Vectors
Annotation
3D Objects
Attributes
Topology
Dimensions
Cadastral
Terrain
Cartography
CAD
Images
Pre Conference Seminar
5
Objects and Object Classes
• Objects are entities with properties and behavior.
• An object is an instance of an object class.
• All objects in an object class have the same properties and behavior.
• An object can be related to other objects via relationships.
A row stores an Object
A table stores an ObjectClass
Pre Conference Seminar
6
Features and Feature Classes
• Builds on the Relational Model
• A feature is a spatial object.
• A feature is an instance of a feature class.
• Extended the relational model with
– Geometry attribute types
A feature class is a table of rows, where
each row has a geographic column
Pre Conference Seminar
7
Geodatabase Supports Advanced Geometry
• Points, lines, polygons, text, and surfaces
• Single and multipart features
• Flexible coordinates
• XY, Z, M, True Curves
• Continuous coverage (not tiled)
One record in feature class table
Feature with many parts
Pre Conference Seminar
8
Feature Datasets
• A container for feature classes
with the same spatial reference
• Analogous to a coverage
– Less restrictive
• Contain geometric networks
and topologies
– Optionally relationship classes
Subdivision
ParcelCorner
Parcel
ParcelAnno
LotLines
Parcel_Topo
LotDimension
BoundaryLine
Pre Conference Seminar
9
Domains
• Describe the legal values of a field type.
– Used to ensure attribute integrity
• Can be shared among classes
• Transfer with the geodatabase
• Types of domains:
– Range
- A tree can have a height between 0 and 300 feet.
- A road can have between one and eight lanes.
– Coded value (e.g., a set)
- A tree can be of type oak, redwood, or palm.
- A road can be made of dirt, asphalt, or concrete.
Pre Conference Seminar
10
Subtypes
• Partition the objects in a class into like groups.
• Defined by the value of a subtype field.
– Have the same attribute schema
– Have the same behavior schema
– Can have different default values and domains for each field
– Can define topology rules between subtypes
Descriptions
Codes
Pre Conference Seminar
11
Relationship Classes
• An association between two object classes.
– A class may participate in multiple relationship classes.
• Related objects can message each other.
– Origin to destination, destination to origin, both, neither.
– Can trigger behavior (cascade delete, move to follow, custom, etc.)
• Associate rules with relationship classes.
Pre Conference Seminar
12
Annotation
• An example of a graphic feature class
• Annotation feature classes may be
– Feature linked
– Non-feature linked
• Composite relationship manages link
• Can store text as well as other graphics
– Lines, arrows, boxes, etc.
• Maplex labeling integrated into ArcGIS
Placerville
feature class
composite
relationship class
annotation feature
class
Sacramento
Topanga Canyon
41
21
43
47
49
23
27
41
92
Placerville
43
92
94
94
Sacramento
47
95
95
Topanga Canyon
Pre Conference Seminar
13
Dimension Features
• Type of annotation that displays specific distances on a map
• Graphic features stored in a dimension feature class
• “Smart” feature
– Special drawing
– Special editing
1 3/8"
Pre Conference Seminar
14
Object Behavior
Class
extensions
Rules
Subtypes
Domains
Datasets
Pre Conference Seminar
15
Architectural Direction – n Tier, Server-Based
3-D
Viewers
Presentation
Tier
(multiple viewers)
COP
2-D
Viewers
Network/Enterprise Service Bus
Catalog
Services
Globe
Services
GeoImageMap &
Processing Processing
Chart
Services
Services
Services
Open
Web
Services
Tracking
Services
Serving/
Publishing
Tier
Authoring
Tier
Pre Conference Seminar
16
ArcGIS Data Models
Templates for Many Fields
•
•
•
•
•
•
•
•
•
•
•
•
•
•
• Historic Preservation
& Archaeology
• Homeland Security
• Hydro
• IHO
• Land Parcels
• Local Government
• Marine
• National Cadastre
• Petroleum
• Pipeline
• Telecommunications
• Transportation
• Water Utilities
Address
Agricultural
Atmospheric
Base Map
Biodiversity
Census-Admin
Boundaries
Defense-Intel
Energy Utilities
Environmental
Forestry
Geology
Groundwater
Health
Geometry Point
Contains M values No
Contains Z values No
Simple feature class
Haul
Allow
Data type nulls
Field name
OBJECTID
SHAPE
HAULJOIN
VESSELCODE
CRUISE
HAUL
STATION_ID
SSTEMP
BOTTOMTEMP
EFFORT
DataSourceID
Object ID
Geometry
Long integer
Long integer
Long integer
Long integer
String
Float
Float
Float
String
Default value
Domain
Precision Scale Length
Yes
No
No
No
No
No
No
No
No
Yes
ArcHydro
0
0
0
0
7
0
0
0
0
0
0
50
Table
FishCatch
Relationship class
HaulHasFishCatch
Type Simple
Cardinality One to many
Notification None
Origin feature class
Name Haul
Primary key HAULJOIN
Foreign key HAULJOIN
Forward label FishCatch
Backward label Haul
No relationship rules defined.
Relationship class
DataSourceHasHaul
Type Simple
Cardinality One to many
Notification None
Origin table
Name DataSource
Primary key DataSourceID
Foreign key DataSourceID
Forward label Haul
Backward label DataSource
NameHaul
Object ID
Long integer
Long integer
String
String
Double
Double
Default value
Domain
No
No
No
No
No
No
Precision Scale Length
0
0
28
21
0
0
0
0
Table
DataSource
Field name
Destination feature class
No relationship rules defined.
Allow
Data type nulls
Field name
OBJECTID
HAULJOIN
SPECIESCODE
LATINNAME
COMMONNAME
WEIGHTCPUE
NUMBERCPUE
Destination table
NameFishCatch
OBJECTID
DESC_
SOURCE
CONTACT
PREC
CREATE_DATE
LAST_UPDATED
DataSourceID
Allow
Data type nulls
Object ID
String
String
String
String
Long integer
Long integer
String
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Default value
Domain
Precision Scale Length
35
35
20
20
0
0
50
. . . Help Users Get Started
. . . Support Consistent Standards
Pre Conference Seminar
17
Role of Data Model Templates
Pre Conference Seminar
18
Design Approach
• Application-Driven Design means
–Understanding the Geo-information needs required to
support business processes
–Documenting the information products and layers
required
–Creating Application/Data matrices to document the
high-level information needs
Pre Conference Seminar
19
Components of a GIS Data Model
Business Needs
Applications & Information Products
Maps, Reports, Views,
Tools, Web Services
Layers
Layer Files,
Map Elements,
Labels
Datasets
Tables, Simple Features, Raster,
Networks, Terrains, …
Pre Conference Seminar
20
GIS Design Methods
Conceptual
Data Model
Information
Products
Maps and
Globes
Layers
Web Services
Entities
Attributes
Relationships
Logical
Data Model
Implementation choices
Implementation details
Datasets, Maps, Layers
Implementation
Tools
Deployment and support
Pre Conference Seminar
21
Contact Information
• sgrise@esri.com
Pre Conference Seminar
22