UML and Object Modeling Elements Longley et al., ch. 9 Zeiler, chs. 4 and 5, and 12 Review Zeiler ch. 1

Data Modeling for Spatial Analysis What is spatial analysis? Methods for working with spatial data –to detect patterns, anomalies –to find answers to questions –to test or confirm theories deductive reasoning –to generate new theories and generalizations Inductive reasoning "a set of methods whose results change when the locations of the objects being analyzed change"

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

Unified Modeling Language Entity-relationship diagrams Design methodologies, diagram notations UML –Not a design methodology –Just a diagrammatic notation –Endorsed by leading software and database companies HTML

UML ( cont. ) diagrammatic notation = “visual language”... for constructing a data model drawings constructed in Visio tools to input a drawing to ArcGIS –input data to the data model

Steps in Data Modeling (1) Model 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 (4) Match to geodatabase elements –specify relationships, “behaviors” (5) Organize geodatabase structure

User’s View of Data

Select geographic rep.

UML Notation pp 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

UML Notation ( cont. ) Abstract class –specify subclasses underneath –Mammals w/human, dog feature classes –no new instances Feature Class –Specify subtypes underneath

Objects and Features Object –An instance of a class (another meaning) –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 –ship, vehicle, … customer, lake, house Feature –an object that has geographic location –a point, line, area, TIN, raster

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

Relationships (cont.) 1:1 - 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 1:n - 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

Relationships (cont.) m:n - 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

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