Introduction to the

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Introduction to the Geodatabase
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• What is a Geodatabase?
• What are feature classes and feature datasets?
• What are domains
• Design a personal Geodatabase
• Import data to a Geodatabase

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What is a Geodatabase?
A relational database that contain geographic
information

• A container for tables, feature classes, feature
  datasets.
• Tables attributes of rows and columns
• Standalone feature classes (conceptually like
  shape files)
• Feature datasets (a collection of feature
  classes)
• Rules and relationships

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Feature classes..

• Store geographic features represented as points,
  lines, or polygons, and their attributes
• Can also store annotation and dimensions.
• Tables may contain additional attributes for a
  feature class

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Feature datasets..

• Feature classes can be organized in Feature
  datasets.
• All feature classes in a feature dataset share
  the same coordinate system.
• Feature classes in a feature dataset can be
  organized into a geometric network. The network
  maintains topological relationships between its
  feature classes.

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Personal vs. Multiuser Geodatabase
Personal geodatabase - stores data in a
Microsoft Access database - size limit 2 GB -
directly read through ArcCatalog - does not
support raster data Multiuser geodatabases -
data stored in IBM DB2, Informix, Oracle, or
Microsoft SQL Server - connected through ArcSDE
or direct - ArcSDE license necessary for
editing - supports raster data
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Why Geodatabase?

• All data (vector, raster, address, measures,
  CAD, etc.) is stored together in a commercial
  off-the-shelf DBMS
• Simplify support and maintenance, and reduce
  costs
• Allows multi-user access (with ArcSDE license)
• Support for intelligent features, rules, and
  relationships between feature classes

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More advantages..

• Dynamic Geocoding
• Annotation subclasses
• Subtypes within Feature classes
• Coded attribute and range domains
• Improved topology and editing

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Confused?

• The geodatabase may seem complicated..

however they are simply modern equivalents of
shapefiles and coverages stored in a commercial
database.
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Geodatabases in ArcGIS

• - Geodatabases can be created and managed easily
  using the standard tools in ArcCatalog
• ArcMap and ArcToolbox provides tools to work
  with geodatabases

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Creating a Geodatabase
Think before you create

• Design process
• Create an empty Geodatabase in ArcCatalog
• Define the database structure
• Set spatial reference and coordinate domains
• Load data
• Define topology rules and relationships

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• Design process
• What data layers to include in the geodatabase
• Shape files Coverages
• Look-up tables
• How to organize the feature classes into logical
  feature datasets
• Think about what topolygy rules you may want to
  apply how are the feature classes related to
  each other spatially?

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Create a new Geodatabase in ArcCatalog
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Migrating existing data into the Geodatabase

• Shape files and coverages are converted to
  feature classes
• Attributes can be left out or renamed
• CAD data, dBase files, annotation etc. can be
  imported
• Data of the same spatial extent can be imported
  to the same feature dataset

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Importing existing data

• In ArcCatalog or ArcToolbox
• Tools and wizards are available
• Works with coverages, shapefiles, tables, CAD
  etc.

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Creating Feature Datasets

• Right-click on the geodatabase New Feature
  Dataset
• Name the Feature Dataset and define the
  coordinate system
• Set X/Y domain
• Set Z domain and M domain
• Set manually or import from existing data sets

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Coordinate Domains
Lost data
Max X and Y is 2.14 billion

Y
Large area Smaller precision (1,000)
Small area larger precision (100,000)
X
(0,0)
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Coordinate Domains

• The coordinate domain defines the area you can
  make edits in
• X and Y max is 2.14 billion for the database
• Default domain is 21000, 21000
• Define your coordinate domains correctly the
  first time they cannot be changed
• You can have a different coordinate domain for
  each feature class

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What is max/min X and Y on the map?
Max X and Y
Min X and Y
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Setting X/Y Domain Precision
1000
Min X 2,145,320 Max X 2,657,580 Min Y
1,632,610 Max Y 1,967,940 1 ft units, 1/1000
ft accuracy Precision 1000/1 1000 (good
enough)
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Coordinate Domains
Max X and Y is 2.14 billion
Y
Most of the data is here in the database Large
expansion options to the north and east
X
(0,0)
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Coordinate Domains Calculations
Min X 2,145,320 Max X 2,657,580 Min Y
1,632,610 Max Y 1,967,940 Precision 1000
These coordinates would put the data in the lower
left corner however we want to shift this to be
able to expand in all directions
(MinX MaxX)/2 (2.14 x 109) / (1000 x 2) X
min 2,401,450 1,070,000
1,331,450 (MinY MaxY)/2 (2.14 x
109) / (1000 x 2) Y min 1,800,275
1,070,000 730,275
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Coordinate Domains Calculations
(MinX MaxX)/2 (2.14 x 109) / (1000 x 2) X
max 2,401,450 1,070,000
3,471,450 (MinY MaxY)/2 (2.14 x
109) / (1000 x 2) Y max 1,800,275
1,070,000 2,870,275
Shifted x/y domain
Default x/y domain
Min X 1,331,450 Max X 3,471,450 Min Y
730,275 Max Y 2,870,275 Precision 1000
Min X 2,145,320 Max X 2,657,580 Min Y
1,632,610 Max Y 1,967,940 Precision 1000
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Coordinate Domains
Max X and Y is 2.14 billion
Y
Most of the data is here in the database Large
expansion options in all directions
X
(0,0)
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The shifted x/y domain allows for editing within
this window
Max X, Max Y
Min X, Min Y
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Why create Feature Datsets?

• Data organization
• Topology rules
• Shared boundaries
• Geometric networks

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Subtypes in feature classes
Subtypes can only be created in ArcEditor and
ArcInfo
- A subtype is a group of objects that have
similar properties within the Geodatabase
For example the attribute ZoneCode may have
subtypes - Commercial, Residential,
Industrial Landcover vegetation types may have
subtypes - Forest, Agriculture, Rangeland, Urban
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Attribute Domains

• Attribute domains are properties of the
  Geodatabase
• - Multiple objects may use the same domain
• - Can be created using the Domains
  properties dialog box
• Defines legal values for field attributes
• - Range domains (allowable numeric value
  range)
• - Coded value domain (in dropdown menus)

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Questions?