ArcGIS Desktop and Geodatabases

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Lecture 3

• ArcGIS Desktop and Geodatabases

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This lecture

• Exploring ArcGIS desktop
• The geodatabase data model
• Building a personal geodatabase
• Creating features
• Editing features and attributes
• Exporting geodatabases
• Geocoding

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ArcGIS Desktop Applications

• ArcCatalog
• ArcMap
• ArcToolbox

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What do we do in ArcCatalog?

• Manage geographic data
• Copy, move, delete data
• Connect to drives on your computer
• Search for data on your drives or across a
  network
• Add/edit metadata
• Drag data into ArcMap
• Export data

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ArcCatalog interface
Toolbars
Catalog Tree
Catalog display (Preview mode)
Geography selected
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ArcCatalog interface
Catalog display (Preview mode)
Table selected
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What do we do in ArcMap

• Displaying map data
• Navigating a map
• Looking at feature attributes
• Editing features and attributes
• Query attributes
• Analyse spatial relationships
• Design map layouts

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ArcMap interface
Map display
Table of contents
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What do we do in ArcToolbox

• Tools to convert spatial data between formats
• Apply map projections
• Analysis tools
• Many tools have wizard interface
• Available from either ArcCatalog or ArcMap

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ArcToolbox interface
ArcCatalog
ArcToolkit window
ArcMap
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Extensions

• Extend the capabilities of ArcGIS with a number
  of products
• Add from the Tools menu in ArcCatalog or ArcMap
• Allows selection of products (subject to license)

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Toolbars for extensions

• Toolbars for these extensions do not
  automatically open. Use View gt Toolbars to open
  (in ArcMap)

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Summary ArcGIS Desktop applications

• ArcCatalog browse, search, preview, manage and
  add (to ArcMap) spatial data
• ArcMap display data, query attributes, analyse
  data and design map layouts
• ArcToolbox tools for converting, projecting and
  analysis of data

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Geodatabases

• New ArcDesktop data format.
• The future for ArcGIS.
• Like a Coverage only stored in an Object
  Orientated Database.
• Local or Personal Geodatabases vs. SDE
  Geodatabases shared on a network.
• SDE databases can be on ArcSDE servers or most
  other databases. They have locking and versioning
  to resolve conflicts if more than one person
  edits a Feature.

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Geodatabases

• Can build them from scratch, import from other
  formats or build using drawings.
• Keep strict Topological and Data Item constraints
  on Features.
• Build Topology and confirm Features have
  appropriate data as they are edited.
• Because of this, are used as the basis of Network
  Analysis.

Geodatabase
Feature Dataset
Feature Class
Features
Workspace
Coverage
Arcs, Polygons etc.
Features
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Object Orientated Databases

• Each feature is an Object stored in the
  Geodatabase.
• Each Feature is of a certain predefined type, or
  Class.
• You can define your own classes, and inherit
  properties from standard classes.
• When your classes inherit from another class,
  they pick up all the Classes Attributes.
• Classes inheriting from another are known as
  Subclasses of a Superclass.

ESRI Simple Edge Feature integer length
Building integer people
House
Has length and people
Also has length
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Constraints

• Geographical.
• Class and data types.
• Variable ranges or categories.

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Example

• Whereas previously youd make an Arc for a road,
  you can now make a Road class from the Simple
  Edge Feature superclass.
• Constrain the Road so it must have a Surface type
  variable picked from a list.
• Subclass Road to make a Motorway class, with a
  Number variable which is constrained between 1
  and 999.

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Building a Geodatabase from scratch

• First decide your requirements. Many parts of the
  creation process cannot be undone later, so get
  it right first time.
• What types of data do you want and what
  constraints?
• What geographical area do you need?
• Are you going to do analysis on the data?
• Build the Geodatabase in ArcCatalog.

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Building the Geodatabase

• Right-click on the Workspace and pick New
• Unless a server is running ArcSDE, youll only
  get the chance to create a Personal Geodatabase.

To connect to an existing SDE database, use
Database Connections.
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Building the Geodatabase

• You set constraints by creating Attribute Domains
  at the Geodatabase level in its Properties.
• These can be ranges or coded values (categories)
  data must fall in.
• These are then applied to specific Feature
  classes.

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Attribute Domains

• Maximum and Minimum range, or build codes for
  categories with associated text descriptions.
• A Default Value for new Features.
• Split policy if a Feature is split, how should
  the Attribute data be handled in each new
  Feature?
• Each gets the default, duplicates the original,
  or is the original value split on the basis of
  the divided length/area.
• Merge policy if two Features joined, how should
  the Attribute data be kept?
• Feature gets the sum of the original, the
  default, or a length/area weighted average.

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Feature Dataset

• Right-click Geodatabase gt New gt Feature Dataset.
• A collection of Features that share a Spatial
  Reference, i.e. area and coordinate system. Set
  this with the Edit button.

Give the Dataset a max/min area and Select a
Projection System.
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Feature Classes

• Right-click Feature Dataset gt New gt Feature Class
• Choose a name and set the field.

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Feature Classes Constraints

• Add new Field.
• For each pick an Alias (alternative name - can
  include spaces), a Default Value, and an
  Attribute Domain if you want constraint.
• Note that Long Integer Integer used when making
  domains.
• Field Properties change when you click on a Field
  Name.

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Table of Contents

• You should end up with something like the
  following.

Geodatabase
Feature Dataset
Feature Class
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Drawing your Geodatabase

• You can also make your Geodatabase schema (i.e.
  structure) using a combination of
• CASE (Computer Aided Software Engineering) tools.
• Allow you to draw software and convert it to
  computer code.
• UML (Unified Modelling Language).
• A standard way of drawing Object Orientated
  things.

ESRI Simple Edge Feature integer length
Occupants text owner integer others
Building inherits from ESRI Simple Edge Feature
Building integer people
Building has attached Occupants data
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Summary

• Geodatabases are a new, highly controlled data
  storage technique.
• When you build one, you can set Attribute Domains
  which are constraints that can be applied to
  Features.
• You build a Feature Dataset for a particular area
  / spatial reference.
• You design Feature Classes e.g. Roads and set
  their constraints.

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Shapefiles another commonly used data format

• Dont store topological geometry or attribute
  information
• A feature is stored a a shape comprising of
  vector coordinates
• Fast to draw and edit
• Support point, line or polygon features
• Attributes in dBASE format

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Other shapefile information

• A shapefile consists of ONLY one feature class
  whereas geodatabases and coverages may contain
  several
• Shapefiles consist of 3 files
• .shp main file
• .shx index file
• .dbf dBASE table
• Good format to move data about

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Geography data input and output
Get geography
Get attributes

• Getting geography data in
• ESRI formats
• other formats
• digitising.
• Editing.
• Exporting data.

Analyse
Output data
Output maps
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Getting geographical data in

• Creating new data
• Manual adding.
• Importing shapefiles, coverages and geodatabases.
• Importing text files.
• Importing other formats.
• Importing from web services.

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Creating new data

• Digitising
• Produces vector data
• Usually produced from paper maps, aerial photos
  or satellite images
• Heads-up digitising
• Digitise image on computer screen
• ArcGIS allows you to create shapes or specify
  angles and lengths of line segments and whether
  they are parallel or perpendicular to other
  segments

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Importing

• Right-clicking on a Workspace, Geodatabase or
  Feature Dataser brings up import and export
  options, so you dont have to build Geodatabases
  from scratch.

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Importing text files

• ArcGIS can import ASCII text files (American
  Standard Code for Information Interchange).
• ArcToolbox Generate to Coverage Wizard..

NB Generate files only include geography, not
attributes.
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Importing other formats

• ArcToolbox has a whole set of tools for
  conversion.
• You can convert from
• Atlas Geo File
• dBASE file
• Digital Elevation Model
• MapInfo Interchange Format
• TIGER (US Census maps)

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Importing from web services

• Web services the Next Big Thing.
• Data storehouses you connect via a menu on your
  GIS, they download the data to you. You dont
  save it locally.
• Ultimately online GIS will do the analysis you
  just get the results.
• Transfer format ultimately GML (Geographical
  Markup Language a form of XML).
• Protocols being put together by the Open GIS
  Consortium includes ESRI (and us!).

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Geography Network

• ESRIs online data warehouse.
• Holds data from many sources.
• ArcGISs ArcMap can access it.
• File gt Add data from Internet
• ArcExplorer can also contact it.
• Data transfer written in Java.

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Geography Network

• Pick locality, dataset and it downloads the data
  from the website into your application.

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Geographic data sources
Convert
Raw coordinates
Other vector GIS
Convert
Paper map
Convert
Raster GIS
Digitise
ASCII coordinate file
Image
Digitise
Convert
Shapefile
Import/Export
ArcInfo coverage
ArcInfo grid
Import/Export
Convert
Generate
Manual entry
Load
Geodatabase
Load
Scan
Source Adapted from Introduction to ArcGIS Part
2 (for ArcView, ArcEditor 8 and ArcInfo 8) v1.2,
ESRI (UK) Training course, 2003
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Get geography
Get attributes

• Getting geography data in
• ESRI formats
• other formats
• digitising.
• Editing.
• Exporting data.

Analyse
Output data
Output maps
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Editing in ArcMap

• Features can be deleted, moved, divided, merged,
  resized, reshaped or buffered
• When features edited, attributes may
  automatically update eg length, area.
• Some attribute data may need manual updating
• Can add new attributes to table

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The Editor Toolbar

• All digitising (creating new features or
  modifying existing ones) is done in an edit
  session
• Start Editing command - on Editor Toolbar
• Stop Editing command also on Editor Toolbar
• When editing session started you specify
• The task the operation, e.g. Create New Feature
• The target layer to which the data is going
  into
• The tool e.g Sketch Tool
• Errors made in editing can be undone on Standard
  Toolbar

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Adding Geodatabase Features

• With a Geodatabase you can pick particular Class
  Features.

Pressing the Attributes icon brings up a selected
Features attributes so you can change them.
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Tasks Modify features etc

• Theres a few additional menu items that might
  help you, if your topology doesnt clean or you
  need to edit your data.
• These are on the Task drop down list of the
  Editor Toolbar.

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Editing existing features in ArcMap

• Select Features Using a Line / Area for when
  you want to select without finishing a sketch.
• Extend / Trim Features Select lines, then
  sketch tool. Draw a line across / beyond selected
  ones. Trimmed to the right of the sketch line /
  extended to the line after Finish Sketch
  selected.
• Modify feature select line, right-click where
  you want to add a vertex. Choose Insert Vertex
  and Finish Sketch (similar for delete).
• Can also be picked to drag Vertices or stretch
  the object depending on setting in Editor gt
  Options gt General gt Stretch geometry
  proportionately...

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Reshape

• Reshape Feature used to cut or add to a polygon
  depending on whether start and end of a sketched
  line are in or out of the Polygon. Cut Polygon
  works similarly but splits rather than deleting.
• Can also be used with the sketch tool to redraw
  shared boundaries between Polygons in the same
  way.

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Editing Topological features

• If youve got a Topology built, when you start
  editing the editor integrates the data. That is,
  boundaries within the cluster tolerance are
  snapped so they become identical.
• The default cluster tolerance is zero. You can
  set this to something else (usually less than the
  precision of your map) and manually integrate
  under Editor gt Options gt Topology.
• Once integrated, there are special tools for
  dealing with joint Polygon boundaries.

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The Topology Edit tool

• The other major tool for shared boundaries.
• Used for dragging shared vertices or boundaries.
• Also used under the reshape feature task to
  select the boundary you want to alter, before
  redrawing it with the sketch tool.

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Autocomplete Polygon

• You can also use AutoComplete Polygon from the
  task list with the sketch tool to add Polygons
  with shared boundaries.

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Get geography
Get attributes

• Getting geography data in
• ESRI formats
• other formats
• digitising.
• Editing.
• Exporting data.

Analyse
Output data
Output maps
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Exporting from Geodatabase

• Can use ArcCatalog to export to different formats
  by right-clicking on the geodatabase

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Geocoding

• Create spatial data (point features) from
  information that describes or names a location
  e.g. an address
• GIS assigns coordinates to data records
• Example Leeds University may want a map of all
  its students to study distribution. If it has
  students address or postcode then it can make
  map.

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How does it do it?

• Address table (in database or text format)
• Reference data on which addresses/postcodes can
  be located (e.g. street map or postcode
  boundaries)
• ArcGIS uses address information in attribute
  table of reference data to work out where to
  place point (representing address of customer)
• Street level reference data will put data at
  correct location along street
• Postcode (Zip) reference data will put point at
  centre of polygon

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Do you need anything else?

• Yes, you need an Address Locator
• The link to Address Locator can be found in the
  catalog tree of ArcCatalog or in the ArcToolbox
  window
• Manages existing locators and create new address
  locators on your computer.
• Depending on the address locator style you
  choose, it defines the rules by which addresses
  are matched from the address table to the
  reference data and suggests adjustments to enable
  fuzzy address matching
• Style chosen depends on geometry in your
  reference data and format of address data

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Matching addresses

• Geocoding also called address matching
• ArcGIS looks at each address in the address file
  and sees if it can match it with address in
  reference data
• Generates a list of probable or possible matching
  locations (candidate)
• Candidate given likelihood score (user can choose
  the score which defines a match)
• Creates a new data set point features of each
  address
• Can geocode individual addresses using Find
  dialog

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Rematching addresses

• Some addresses will not match either because
  reference data is incomplete or because of
  incorrect entry in address file
• Can rematch automatically (all at once) after
  adjusting matching options
• Rematch interactively (one at a time) have
  additional options.

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What is the output from geocoding?

• Shapefile or geodatabase feature class of points
• Geocoded data attributes of the address table,
  some of the reference data attributes and,
  optionally, new attributes, e.g. x,y, coordinates
  of each point.

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Summary Geocoding

• Create point data from address information
• Require
• Address file
• Reference data
• Address locator
• ArcGIS matches address data from address file
  with address data from reference data
• Produces a point file in shapefile or geodatabase
  format

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Practical

• Create a personal geodatabase
• Create feature classes
• Add fields and domains
• Keep safe for a later practical

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Next week

• Displaying data
• Presenting data
• Querying
• Attribute tables