Features, Formats

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Features, Formats Attributes

• GIS 458
• Spring 2006

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Layer Types

• Vector
• Raster
• Terrain and Other Surfaces
• Other
• Addresses
• Geoprocessing Models
• Survey Data
• Networks

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Vector Data

• Discrete Data
• Have precise shape and position
• Best for defined shapes and boundaries
• Have attributes and behavior
• Points
• Zero-Dimensional
• Features too small to be lines or areas
• Stored as single x,y coordinates

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Vector Data

• Lines
• One-Dimensional
• Features too narrow to be areas
• Stored as series of ordered x,y coordinates
• Segments
• Straight
• Circular
• Elliptical
• Splined
• Polygons
• Two-Dimensional
• Features that cover a broad geographic area
• Stored as series of segments that enclose an area
• Annotation
• Descriptive labels
• Associated with features
• Display names and attributes

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Raster Data

• Gridded data composed of cells or pixels (picture
  elements)
• Two-Dimensional
• Values can depict various data
• Light values (spectral)
• Elevation (thematic)
• Density (thematic)
• Discrete or Continuous
• Can also be stored in an attribute field
• Photo of a building

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Terrain Other Surfaces

• Triangulated Irregular Network (TIN)
• Model of a surface
• Stored as
• Integrated nodes
• Triangles with edges
• Enable surface analysis
• Cannot be stored directly in geodatabase

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Other Layer Types

• Addresses
• Data stored in database
• Locators create features for locations
• Geoprocessing Models
• You create tools and store them
• Survey Data
• Data tables tied to feature coordinates
• Networks
• Require connectivity topology

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Attributes

• Quality of an object
• Size
• Density
• Name
• Flow
• Date
• Population
• A feature can have a number of attributes
• Allow analysis symbolization

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GIS 458

• Spring 2006
• Instructor Larry Clamp

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Course Topics

• Design Process
• Layer Design Formats
• Raster vs. Vector
• Point, Line or Polygon?
• Relationships
• Spatial
• Non-Spatial
• Attribute Table Design
• Defining Appropriate Fields
• Assigning Appropriate Field Types
• Text, Integer, Double

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Course Topics, continued

• Database Fundamentals
• Purpose
• Personal vs. Enterprise
• Database Design
• Database Implementation

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Course Topics, continued

• Software Selection
• Database software (Oracle, SQL, etc.)
• GIS Softwareis ESRI the best?
• Data Standards
• FGDC
• Personnel
• Project Management
• Data Mining

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BREAK!!!!
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GIS (Geographic Information System)

• Consists of
• Computer hardware
• Software
• Geographic data
• Personnel
• Is a computer system that stores and links
  geographically-referenced information with
  graphic map features to allow a wide range of
• Information processing and retrieval
• Display operations
• Map production
• Analysis, and
• Modeling

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Benefits of a GIS (Functionality)

• Data entry/updating access the database to
  update, add or delete information
• Data conversion take diverse information,
  formats, etc. and make them compatible
• Data retrieval take massive amounts of stored
  information and access it
• Data manipulation select via query and classify
  (symbolize) in different manners
• Data presentation present retrieved information
  in either text, tabular or map format.
• Spatial analysis take spatial data and make
  queries (from simple to complex) and generate new
  data from the original set

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Three general operations in a GIS

• 1. Attribute queries (aspatial queries)
• How many parcels in an attribute table are zoned
  R-7 and what is their total acreage?
• 2. Spatial queries
• How many pulp plants are located within 500
  meters of a river?
• 3. Generation of new data sets from the original
  database
• Out of a marine mammal dataset, where are just
  the Beluga whales located?
• Are there areas where ring seals and orcas
  overlap?

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What is Spatial Data?

• Spatial means it is mappable, that is, every
  piece of information is attached to a specific
  object on the map and that objects location on
  the map is geographically-referenced
• Reference systems typically use
  latitude/longitude, UTM, SPC or some type of x,y
  coordinate system

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Where do we get Spatial Data?

• From a variety of sources
• U.S. census
• Land use surveys
• Satellite imagery
• Aerial photographs
• Paper maps
• Problem compatibility
• Projections/coordinate systems--Albers Equal-Area
  Conic vs. UTM
• Map scale--12,000 vs. 12,000,000
• Data formats--DRG, (raster), Shapefile (vector)

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Examples of GIS Data Structures
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Organizing Geographic Data

• GIS 458
• Spring 2006
• Larry Clamp

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Parts of the Whole

• Geodatabase
• Geographic Datasets
• Object Classes
• Feature Classes
• Topological Classes
• Relationship Classes

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Geodatabase

• A collection of data types
• Datasets feature, object and relationship
  classes
• Can span one, several, or many geodatabases
• Manage seamless geographic data
• Two main types
• Personal
• Represent small to medium-sized datasets
• Enterprise
• Represent large or complex datasets (multiple
  users)

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Geographic Datasets

• Feature Dataset
• Collection of feature classes
• Common coordinate system
• FCs must be in FDs for topology
• Raster Dataset
• Simple (basic GRID)
• Compound (multiple bands, etc.)
• Triangulated (TIN) Dataset

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Object Classes

• Table that can associate behavior
• Descriptive information about objects
• Owners
• Stream Codes
• Annotation

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Feature Classes

• Collection of features with same geometry
• Points, lines, polygons
• Simple feature classes
• No topology
• Features are independent of one another
• Topological feature classes
• Features are bound to one another
• Share certain behavior

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Relationships
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Relationships
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NoSeriously

• Relationship class
• Table that stores realtionships between features
  or objects
• Models dependencies between objects
• Can control what happens to related objects
• Removed
• Changed

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Keep it Simple

• Geodatabase Filing Cabinet
• Feature Dataset Filing Cabinet Drawer
• Feature Class Individual Folder in Drawer

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Sub-Types Attribute Domains

• GIS 458
• Spring 2006
• Larry Clamp

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Sub-Types

• Objects (rows) in a table or feature class
  grouped by an attribute
• Roads by class Highways, major roads, arterials,
  etc.
• Allow users to make validation rules more
  specific to data
• Help insure data quality
• Speed up data entry and editing
• Help eliminate need for additional classes
• Wells Different class for public, agricultural
  or monitoring wells or
• Just different sub-types?

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Sub-Types, continued

• Based on integer attribute field
• Integer codes and descriptions entered
• Editor constrained to entered values
• In ArcMap, description is displayed
• Description used for labeling

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Setting Sub-Types

• Set as properties of an existing table or feature
  class
• Go to Properties dialog
• Select integer sub-type field
• Input code and description
• Can also set defaults and domains

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Attribute Domains

• Define legal field values for tables, feature
  classes, or sub-types
• Defined as properties of the geodatabase
• Can be shared across the geodatabase
• Assigned to fields by editing field properties of
  tables feature classes
• Do not constrain incorrect data entry but will
  find errors
• Validation tool on Editor menu

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Legal Values

• Two Types of domains
• Range and Coded Values
• Type used depends on nature of attribute data

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Range vs. Coded Values

• Range domains
• Apply to values for numeric attributes
• Used for measured data
• Well depth
• Contamination levels
• Power pole heights
• Legal minimum and maximum

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Range vs. Coded Values

• Coded values
• Apply to any type of attribute
• Text, numeric, date, etc.
• Used for coded data
• Land-use codes
• Water pipe material codes
• Street surfacing codes
• Define list of legal codes and their descriptions

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Splitting Merging Features

• Domains allow you to define how attributes are
  handled during splitting merging
• Split policy
• Merge policy

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Split Policies

• Defines what values are assigned to resulting
  features
• Default value
• Each take on a default value you set
• Duplicate value
• Each take on a copy of original value
• Geometry ratio
• Each take on a ratio of the original value

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Merge Policies

• Dictates what happens to values of merged
  features
• Default value
• Each take on a default value you set
• Only policy that applies to nonnumeric fields and
  coded value domains
• Sum
• Sum of the original features
• Geometry weighted
• Weighted average of original features

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Summary
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Table Design Importing Data

• GIS 458
• Spring 2006
• Larry Clamp

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Ways to create tables

• ArcCatalog
• Right click location
• Folder, geodatabase
• Select NewgtTable to access wizard
• You can import fields from other tables
• Geoprocessing (ArcToolbox)
• Under Data Management Tools
• Select Table toolset gt Create Table

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Table Field Properties

• Alias
• Allow NULL Values
• Default Value
• Domain
• OBJECTID
• Length
• Precision
• Scale
• BLOB
• Raster

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Alias

• Alternate field name for display in ArcMap
• Less cryptic
• Can be changed after the table is created

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Allow NULL Values

• Indicates field may or may not contain null data
• Null value absence of recorded value
• Different than 0 (which is a value)
• May NOT be changed after table is created

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Default Value

• Value that is automatically assigned for a new
  record
• May be changed after table is created

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Domain

• Assigned geodatabase domain for field
• Defines legal values
• Can also define how feature attributes are
  handled if they are merged or split
• May be changed after table is created

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OBJECTID

• Automatically generated
• DO NOT delete or change it in any way!!

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Length

• Maximum number of characters to store in text
  field
• Set as an integer

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Precision

• Maximum number of digits for a numeric field
• Set as an integer

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Scale

• Maximum number of decimal digits for a decimal
  numeric field
• Set as an integer

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BLOB

• Binary large object
• Data stored in the geodatabase as a long sequence
  of binary numbers
• Stores images, multimedia, or bits of code
• ArcGIS doesnt provide end-user tools
• Must write custom objects or applications to
  manage a BLOB field

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Raster

• New attribute type
• Stores raster within or alongside the geodatabase
• ArcGIS views many file formats but outputs as a
  GRID, IMAGINE, or TIFF
• Will convert for you
• Only one raster field allowed in a table or
  feature class
• Use a different table with a relate to associate
  more

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Naming Conventions

• Table name, feature class and field names must be
  compatible with underlying RDBMS
• For ESRI this means
• No spaces
• Use underscores or run words together
• Field names limited to ten characters
• Use an alias for more descriptive name

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Field Data Types
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Importing Data (vector data)

• IMPORT tools
• ArcCatalog context menu or
• Geoprocessing tools
• Simple Data Loader (ArcCatalog)
• Loads to existing table or feature class
• Empty or with data)
• ArcMap Object Loader
• Loads to existing table or feature class
• Empty or with data)
• Work for both personal or enterprise GDB

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IMPORT tools

• ArcCatalog menus
• Right click on location to import
• Geoprocessing tools
• ArcToolbox gt Conversion Tools gt To Geodatabasae
• Both use same tools

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Simple Data Loader

• ArcCatalog context menus wizard
• Loads data into an existing table or feature
  class
• Object may be empty or contain data
• Data sources must have same schema (multiple)
• Feature classes
• Target and source MUST have same geometry
• Can query to import only selected data
• Geometric networks versions not supported

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Object Loader

• Accessible only in ArcMap edit session
• Must add as a custom tool
• ToolsgtCustomizegtCommandsgtData Converters
• Loads complex data to table or feature class
• Supports behavior as it loads
• Object may be empty or contain data
• Data sources must have same schema (multiple)
• Feature classes
• Target and source MUST have same geometry
• Can query to import only selected data

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The Geodatabase Design Process

• GIS 458
• Spring 2006
• Larry Clamp

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Why is Good Design Necessary?

• Questions to Answer
• How can we employ GIS technology to
• Improve existing functions?
• Change goal achievement?
• What data is most beneficial?
• What data can be acquired stored?
• Who will maintain the database?
• Establish Process to
• Define goals
• Identify, analyze and evaluate alternatives
• Agree on implementation plan

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Design Objectives

• Avoid risks of lack of design
• Satisfy objectives and requirements
• Obtain necessary data
• Avoid unnecessary redundancy
• Organize data for different users
• Accommodate different data views
• Divide maintenance and users
• Appropriate feature representation, organization
  coding

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Benefits of Design

• Time consumingbut worth it!
• Increased data retrieval analysis flexibility
• Increased user application development
• Better cost distribution
• More users supported
• Support for future development
• Less data redundancy

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Design Guidelines

• Involve Users
• One Step at a Time
• Build a Team
• Be Creative
• Create Deliverables Milestones
• Keep Goals and Objectives in Focus
• Dont Add Detail Too Soon
• Document Carefully!!!!!!
• Be Flexible
• Use Model to Plan

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Design Steps

• Model the Users View
• Define Entities (features objects) and
  Relationships
• Identify Proper Entity (features objects)
  Representation
• Match These to the Geodatabase Model
• Organize into Geographic Datasets

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Model the Users View

• Ensure common understanding between designers and
  users
• Identify Organizational Functions
• Business or service functions processes are
  more stable than business organization
• What do they do?
• Identify Data Requirements
• Interact!
• Who uses it and what is the nature of
  interaction?
• Organize Data into Logical Groupings
• Develop an Initial Implementation Plan

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Define Entities and Relationships

• Broad to Narrow
• Identify Describe Entities
• Use detail
• Involve end users!
• Identify Describe Relationships
• Use descriptive interpreting statements
• Use Diagrams to Show E R
• Unified Modeling Language

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Identify Proper Entity Representation

• Classify by Type of Representation
• Will it be used on a map?
• Is shape significant for analysis?
• Can it be accessed and visualized through
  relationship to another feature?
• Will it have different representations at
  different scales?
• Does it need annotation?
• Should it be a
• Point, line or polygon
• A surface, raster, image, photo or drawing
• An object
• No point, line or polygon required
• No geometric or graphic representation

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Match to the Geodatabase Model

• Determine Geodatabase Representation
• Simple Features
• Discrete
• No Topology
• Complex Features
• Discrete
• Topology or participation in a network
• Points
• Lines
• Polygons
• Images
• Surfaces
• Object

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Organize into Geographic Datasets

• Identify Name Datasets
• Group Feature Classes
• Large feature class
• Subtypes
• Custom behavior
• Substantially different attributes
• Different access requirements
• Define Topology Needs
• Feature classes participating in topology or
  network must be in the same feature dataset
• Group in Geodatabase(s)
• Different departments
• Size limits