Geography 176B: Technical Issues in GIS

1
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.

2
What will I learn in Geog 176B?

• Build depth on Geog 176As 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

3
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

4
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

5
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

6
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

7
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

8
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(intSour
  ceIndex)       Set pFeat pCursor.NextFeature
  Wend  

9
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)

10
The Coverage paradigm
11
ESRIs Field Models

• Images
• Rasters (Grid lattice)
• TINs triangulated irregular networks surfaces as
  meshes of triangles

12
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

13
Geodatabase paradigm
14
Three software components

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

15
ArcGIS Geodatabase
16
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
17
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
18
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.

19
Relationship
Relationship between non-spatial objects
Water Quality Data
Water Quality Parameters
20
Relationship
Relationship between spatial and non-spatial
objects
Water quality data (non-spatial)
Measurement station (spatial)
21
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

22
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

23
Arc Map
View and edit data
Analyze data (Geoprocessing)
Create maps
24
Arc Catalog
Graphical previews
View data (like Windows Explorer)
Tables
Metadata
25
Arc Toolbox
Map Projections
Tools for commonly used tasks
26
Classic ArcInfo v7 Legacy

• ArcGIS Workstation
• Coverage data model
• Command line interface
• Unix or NT hidden by ArcInfo Desktop

27
Extensions

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

28
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

29
Transportation model
30
Model detail UML Description
31
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

32
Tom Grubers 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

33
Example Land Use Maps

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

34
(No Transcript)
35
(No Transcript)