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 •
[email protected]
Pre Conference Seminar
22
