Geospatial Information System GIS Lecture 4

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Geospatial Information System (GIS)Lecture 4

• University of Notre Dame
• Center for Research Computing
• February 10th, 2009

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Overview

• Login to terminal
• Click on AFS VBScript icon on Desktop
• Review Lecture 3 (posted on Wiki page)
• Lecture 4
• Lab

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Review Previous Lecture

• Georeferencing
• Coordinate systems
• Datums
• Projections and distortion
• Projecting data

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Course Outline

• Lecture 1 Course Overview and GIS Basics
• Lecture 2 Creating maps features
• Lecture 3 Projections Data Transforms
• Lecture 4 Attribute Tables
• Lecture 5 Spatial Data
• Lecture 6 Remotely Sensed Data
• Lecture 7 Creating Graphs, Maps, Documents
• Spring Presentations (date/time/location TBD)

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Lecture 4 -- Outline

• Table structure
• Data types
• Table manipulation
• Connecting tables

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Table Structure

• Descriptive information about features
• Each feature class has an associated table
• One row for each geographic feature

Right-click
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Table Structure

• Basic table properties
• Records/rows and fields/columns
• Column types can store numbers, text, dates
• Unique column names

Columns (fields)
Attributevalues
Rows(records)
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Tabular Data Field Types

• Different field types store different kinds of
  values
• Choose the right field type for the right value
• Field types vary according to table format

Name Jupiter Moons 16 Diameter 142,984 km Date
of Comet Shoemaker-Levy impact
7/16/1994 Rotation period 9.8 hr
Text
Date
Short
Long
BLOB
Float
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Table Functionality

• Open table in ArcMap or preview in ArcCatalog
• Sort ascending or descending
• Freeze/Unfreeze fields
• Statistics
• Print
• In ArcMap
• Turn fields on/off
• Select records
• Modify table values
• Calculate Geometry

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ArcGIS Tabular Formats

• Each ArcGIS spatial format has a native tabular
  format
• Coverage INFO
• Shapefile .dbf
• Geodatabase RDBMS tables
• Create a link between related tables in ArcMap
• Direct support for MS Excel tables (read only)
• Use ArcCatalog to connect to external tables
• Using OLE DB

ArcGIS can convert between formats
OLE Object Linking and Embedding
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Associating Tables

• Can store attributes in feature table or separate
  table
• Associate tables with common column key values
• Must be same data field types
• Must know table relationships (cardinality)

Additional attribute table
Feature attribute table
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Table Relationships

• How many A objects are related to B objects?
• Types of cardinality
• One-to-one, one-to-many or many-to-one, and
  many-to-many
• Must know cardinality before connecting tables

One parcel has one owner
One parcel has many owners
Many parcels have one owner
Many parcels have many owners
or
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Joins and Relates

• Two methods to associate tables in ArcMap based
  on a common field
• Join appends the attributes from one onto the
  other
• Label or symbolize features
  using joined
  attributes
• Relate defines a relationship between two tables

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Connecting Tables with Joins

• Physical connection between two tables
• Appends the attributes of two tables
• Assumes one-to-one or many-to-one cardinality

ZoneCodeDesc
Parcel (before Join)
Many-to-one
Parcel (virtual table after Join)
Parcel
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Connecting Tables with Relates

• Define relationship between two tables
• Tables remain independent
• Additional cardinality choices
• One-to-many, many-to-many
• Discovers any related rows

2) Open related table
1) Make selection
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Questions?

• Lab Setup
• Follow the instructions on the sheet provided
• Raise your hand if you need assistance

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