Geography 176B: Technical Issues in GIS Lectures 2 per week Labs: 6, with extensive support material www.geog.ucsb.edu/~ta176/g176b/home.html Use of the Star lab Can also use ArcGIS educational license Text: Paul A. Longley, Michael F. Goodchild, David J. Maguire, and David W. Rhind (2005) Geographic Information Systems and Science. 2 ed. New York: Wiley. Evaluation: Grades are 50% for the six labs (Lab 1 is pass/fail), plus 25% on mid-term and 25% on final.

What will I learn in Geog 176B? Build depth on Geog 176A’s breadth Prior to Mid-term: Learn data modeling and GIS design After Mid-term: Analysis, management and research issues Along the way: Some applications After 176B: 176C Applications of GIS Goal is to increase your knowledge of GIS to system user level, both theory and practice

What kinds of users exist for GIS? 1. System developers: high level of technical skills programmers in C++, Java, Visual Basic: order 1,000 jobs 2. System maintainers: moderate technical skills programmers in UML, Visio, CASE, Visual Basic: order 10,000 jobs 3. System users: modest technical skills, know how to use the tools, familiar with the technical issues , know the application domain, work for governments, corporations, universities, manage others: order 100,000 jobs 4. General public: minimal skills know how to use some tools: order 1,000,000 people 5. Mass consumption: Use Internet-based GIS mapping tools or location systems e.g. Google Earth: 100,000,000 people 6. Benefit from GIS technology: Almost everyone

What do you need to know to be a success as a (3) System user? Basic principles that survive software changes How to be a demanding skeptic Demand better documentation Demand/create accurate data that reflect the real world Reliable and accurate results Fixes for bugs What GIS means What are the limitations What (other) operations are possible

What about practical training? Software changes often (every 2 years) Always possible to acquire training Hands-on experience reinforces basic principles Encourages you to be a demanding skeptic Encourages thinking about what GIS means E.g. Classic ARC/INFO (Workstation) the workhorse of GIS Engine behind ArcView Versions 1, 2, 3 Command-line interface Required syntax, difficult to learn and use still many fans

ArcGIS 8.0 onward several hundred person-years invested complete rewrite, first since 1980 released in 2000 version 7 became ArcInfo Workstation version 8 added ArcInfo Desktop WIMP, wizards ArcView as a subset ArcGIS 9.0 in 2005 Now at 9.1

ArcGIS Overview Hardware and software (UNIX/Mac) Microsoft NT (2000, XP, etc) Intel hardware "wintel" COM: Component Object Model Microsoft standard for re-usable software components geographic objects and software objects any components can be linked interoperability with any COM-compliant software

Example of ArcGIS and Excel working together programmed in Visual Basic for Applications (VBA): ‘Pass Excel the U column vector(vector of known source values)’ While Not pFeat Is Nothing       strRow = GetRow(pFeat.Value(0)) ‘GetRow is user-defined       strCol = "A"       Sheets("Sheet2").Select 'Store vector on Sheet 2 in Column A       Range(strCol & strRow).Value = pFeat.Value(intSourceIndex)       Set pFeat = pCursor.NextFeature Wend  

ESRI Data models: how Redlands describes the world Shapefiles points, lines, areas attributes ArcView heritage No topology Relatively open source Coverages (layers) areas as boundary networks lines as boundaries of areas points as collapsed areas Classic Arc/Info legacy (includes E00)

The Coverage paradigm

ESRI’s Field Models Images Rasters (Grid: lattice) TINs triangulated irregular networks surfaces as meshes of triangles

Geodatabase ArcGIS moved to a new model based on object-oriented methods Objects (e.g. features) have classes Software is component-based Geodatabase is a “collection”, so can contain models of different types

Geodatabase paradigm

Three software components: ArcCatalog managing data data preview metadata ArcMap display, windows, layouts Cartography, coordinates, projections ArcToolbox analysis some transformations mostly for coverages

ArcGIS Geodatabase Workspace Geodatabase Feature Dataset Feature Class Geometric Network Object Class Relationship Workspace

Object Class An object class is a collection of objects in tabular format that have the same behavior and the same attributes. An object class is a table that has a unique identifier (ObjectID) for each record

Feature Class A feature class is a collection of geographic objects in tabular format that have the same behavior and the same attributes. Feature Class = Object class + spatial coordinates

Relationship A relationship is an association or link between two objects in a database. A relationship can exist between spatial objects (features in feature classes), non-spatial objects (objects in object classes), or between spatial and non-spatial objects.

Relationship Water Quality Data Water Quality Parameters Relationship between non-spatial objects Water Quality Data Water Quality Parameters

Relationship Relationship between spatial and non-spatial objects Water quality data (non-spatial) Measurement station (spatial)

Network A network is a set of edges (lines) and junctions (points) that are topologically connected to each other. Each edge knows which junctions are at its endpoints Each junction knows which edges it connects to

Introduction to ArcGIS How data are stored in ArcGIS Components of ArcGIS – ArcMap, ArcCatalog and ArcToolbox Extensions of ArcGIS – spatial analyst, geostatistical analyst and 3D analyst

Arc Map View and edit data Analyze data (Geoprocessing) Create maps

(like Windows Explorer) Graphical previews View data (like Windows Explorer) Arc Catalog Tables Metadata

Arc Toolbox Map Projections Tools for commonly used tasks

Classic ArcInfo v7: Legacy ArcGIS Workstation Coverage data model Command line interface Unix or NT hidden by ArcInfo Desktop

Extensions geostatistics logistics analysis and modeling with rasters Networks Surveying/CAD Military etc

Application environment 2,000 reusable software objects (COM) Programmable in Visual Basic for Applications (VBA) Data modeling with Unified Modeling Language (UML) Model builder extension Visio model: ESRI “templates”

Transportation model

Model detail: UML Description

Building an application Define a schema What objects are important to my application? Build an ontology Create the schema's tables using ArcGIS wizard Populate the tables Go to work

Tom Gruber’s Definition ontology is a specification of a conceptualization. A description (like a formal specification of a program) of the concepts and relationships that can exist for an agent or a community of agents For GIS, a set of geographical objects with their models and relations Critical for interoperability

Example: Land Use Maps Map 1: Map 2: 20 classes Wetlands one class Digitized polygons with 40 acre MMU Map 2: 75 classes Wetlands specified by species: Forested/Non-Forested Second layer of permanent/seasonal Values assigned as classes to cells