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?
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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?
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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
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Engine behind ArcView Versions 1, 2, 3
Command-line interface
Required syntax, difficult to learn and use
still many fans
ArcGIS 8.0 onward
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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
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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 userdefined
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
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points, lines, areas
attributes
ArcView heritage
No topology
Relatively open source
• Coverages (layers)
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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
Relationship
Object Class
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), nonspatial objects (objects in object classes),
or between spatial and non-spatial
objects.
Relationship
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
Create maps
Analyze data
(Geoprocessing)
Graphical
previews
View data
(like Windows Explorer)
Arc Catalog
Tables
Metadata
Arc Toolbox
Map Projections
Tools for commonly used tasks
Classic ArcInfo v7: Legacy
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ArcGIS Workstation
Coverage data model
Command line interface
Unix or NT hidden by ArcInfo Desktop
Extensions
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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:
– 20 classes
– Wetlands one class
– Digitized polygons with 40 acre MMU
• Map 2:
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75 classes
Wetlands specified by species: Forested/Non-Forested
Second layer of permanent/seasonal
Values assigned as classes to cells