Creating a GeoDatabase

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Creating a GeoDatabase
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GeoDatabase

• Supports a model of topologically integrated
  feature classes
• In a relational database
• In some applications database designers will be
  needed to tune the database operation!
• Use can be simple or very complex!

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You need to consider ...

• What kind of data will be in the GDB
• What will be the projection used?
• What rules of data modification will be required?
• Do you want to maintain relationships between
  objects of different types?
• Will you be using geometric networks?
• Will you require topologically related features?
• Will you store custom objects?

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Definitions
What...

• Do all those words mean??????????

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You need to consider ...

• What kind of data will be in the GDB
• What will be the projection used?
• What rules of data modification will be required?
• Do you want to maintain relationships between
  objects of different types?
• Will you be using geometric networks?
• Will you require topologically related features?
• Will you store custom objects?

• Connectivity Constraint on the type of network
  features that may be connected to one another
• edge-junction rules
• edge-edge rules
• Topology Permissible relationships of features
• within a feature class
• between feature classes
• between features in two different feature classes

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You need to consider ...

• What kind of data will be in the GDB
• What will be the projection used?
• What rules of data modification will be required?
• Do you want to maintain relationships between
  objects of different types?
• Will you be using geometric networks?
• Will you require topologically related features?
• Will you store custom objects?

Associations or links between two or more objects
in a GDB. Relationships can exist between 1)
spatial objects (features in a feature class) 2)
non-spatial objects (records in a table, or 3)
spatial and non-spatial objects
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You need to consider ...

• What kind of data will be in the GDB
• What will be the projection used?
• What rules of data modification will be required?
• Do you want to maintain relationships between
  objects of different types?
• Will you be using geometric networks?
• Will you require topologically related features?
• Will you store custom objects?

Objects The representation of a real world
entity stored in a GDB. An object has properties
and behaviors.
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You need to consider ...
A one dimensional nonplaner graph (mathematics)
that is composed of features.These features are
constrained to exist within the network and can,
therefor, be considered network features.

• What kind of data will be in the GDB
• What will be the projection used?
• What rules of data modification will be required?
• Do you want to maintain relationships between
  objects of different types?
• Will you be using geometric networks?
• Will you require topologically related features?
• Will you store custom objects?

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You need to consider ...

• What kind of data will be in the GDB
• What will be the projection used?
• What rules of data modification will be required?
• Do you want to maintain relationships between
  objects of different types?
• Will you be using geometric networks?
• Will you require topologically related features?
• Will you store custom objects?

Relationships between connected features in a
geometric network ORShared borders between
features in a topology (Now that is circular!!!!)
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You need to consider ...

• What kind of data will be in the GDB
• What will be the projection used?
• What rules of data modification will be required?
• Do you want to maintain relationships between
  objects of different types?
• Will you be using geometric networks?
• Will you require topologically related features?
• Will you store custom objects?

Custom Objects In ArcGIS you are NOT limited to
the objects provided. New objects can be added
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More Definitions Feature

• An object class in a GDB that has a field of type
  GEOMETRY.
• Are stored in Feature Classes
• A representation of a real world object
• A point, line or poly in a coverage or shapefile
• A representation of a real world object in a
  layer on a map.

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More yet Feature Class

• Conceptual representation of a category of
  geographic features.
• Includes point, line, poly annotation
• In a GDB, an object that stores features and has
  a geometry field type

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Feature Dataset

• A collection of feature classes that share the
  same spatial reference.
• It is because they share the same spatial
  reference that they can participate in
  topological relationships with each other.
• Several feature classes with the same geometry
  may be stored in the same feature dataset.
• Object geometry and relationship classes can
  also be stored in a feature dataset

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Some others

• Edge
• A line segment in a topology that defines lines
  or polys boundaries
• Multiple features in one or more feature classes
  may share topology edges
• Dataset
• Any feature class, table, or collection of
  feature classes or tables in the GDB
• A named collection of logically related data
  items arranged in a prescribed manor

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Icons
GDB
Feature Dataset
GDB table
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Icons
GDB
Feature Dataset
GDB table
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Icons
GDB
Feature Dataset
GDB table
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Three ways to create a GDB
Plan it
Create a Schema with ArcCatalog
Import Existing Data
Use CASE tools
Define connectivity rules, relationships
Load data into SchemaShapefilesCoverages
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Three ways to create a GDB
Schema?
The structure or design of a database
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Three ways to create a GDB
CASE Tools...
Computer Aided Software Engineering .. Make
Blueprint of GDB Structure in UML (Unified
Modeling Language) like VISIO.
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GeoDatabase items

• Feature datasets
• Spatial Reference
• Spatial Index
• Field Properties
• Field Precision and Scale
• Required Fields
• Topologies
• Geometric Networks
• Relationship Classes
• Data Types

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Feature Datasets (FDS)

• Exist in a GDB to define a particular Spatial
  Reference
• Are a way to group feature Classes(FC) with the
  same spatial reference
• So they can participate in topological
  relationships with each other
• Topologically related FCs must reside in the same
  FDS

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Spatial Reference

• A coordinate System
• Geographic
• UTM
• Etc.
• A spatial domain (coord range, measures (M), and
  Z values
• Precision ( of system units/unit M)
• MUST be specified when creating a FDS and it
  feature classes or a stand alone feature class

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Spatial Index

• Each feature class has a spatial index that is
  generated automatically and maintained by the
  ArcInfo System
• Use to quickly locate features in a dataset that
  might match criteria for a spatial search
• Basically a 2D grid the spans the feature class
• The spatial index grid is changeable

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Field Properties

• When creating a Feature Class or table you can
  specify the number of fields to be included
• And you can spec settings such as field type and
  max. size
• All fields have property default values, domains,
  aliases, and null allowance

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Field Properties

• When creating a Feature Class or table you can
  specify the number of fields to be included
• And you can spec settings such as field type and
  max. size
• All fields have property default values, domains,
  aliases, and null allowance

Valid set or range of values for the field
Set values at creation time
Yes or NO for allowing nulls (nothing)
Aliases will display on maps
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Field Precision Scale

• Max. field size and precision
• Precision number of digits (not the .)
• Scale number of decimal places
• Personal GDBs support ONLY binary fields and
  precision and scale are ignored!
• NOT SO for enterprise GDB!!!

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Required Fields

• Apply to all feature classes and tables
• Automatically created
• Required fields also have required properties
  (domain) cant change
• Required fields for simple FCs are
• OBJECTID
• Shape
• Note when you import data there will be other
  fields you cannot change in ArcGIS But you can
  change them in ACCESS

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Topologies

• Many datasets have features that could share
  boundaries or corners
• By creating a Topology you set up rules defining
  how features share their geometries.
• Editing a boundary or vertex shared by two or
  more features updates the shape of all of them.

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Topology rules

• Govern the relationships between between features
  within a FC or features in different FCs
• Example moving a slope boundary in in one FC
  could update two slope class polys AND update a
  forest stand boundary in another FC.
• Topology editing tools in ArcMap are used to
  create and change the rules

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Geometric Networks

• Some vector datasets need to support connectivity
  tracing and network connectivity rules
• Communications
• Pipelines
• Transportation (roads, railroads, canals)
• Geometric networks allow you to turn simple point
  and line features into network edge and junction
  features

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Relationship Classes

• These define relationships between object in the
  GDB
• One to one
• One to many
• Many to many
• A given feature, table,or row may be related to
  another and creating, editing, or deleting that
  feature may have a specific effect on the other.
• These are composite relations
• Example deleting a pole could result in the
  deletion of a transformer or the maintenance
  records in a related table!

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Data

• Numeric data can be stored in 4 types
• Short integer
• Long integer
• Single precision floating point (floats)
• Double precision floating point (doubles)

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Decimal vs. Binary

• Important concept
• 8,4,2,1 place weight
• The binary number 0110 6 in decimal
• 0001 1, 0010 2, 0011 3, 0100 4
• The short integer is 16 bits or 2 bytes
• One is for sign leaving 15 for the number
• Range is 32,000 to 32,000
• The long integer is 4 bytes or 32 bits
• Range is 2 billion to 2 billion (more or less)

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Decimal vs. Binary

• Floats and doubles are coded in a form similar to
  scientific notation
• -3,125 ? -3.125 x 103 ? 3.125E3
• Float is a 8 bit number and store up to 7
  significant digits
• -3.4E-38 to 1.2E38 for neg numbers
• 3.4E-38 to 1.2E38 for positive
• As a result floats and doubles are only
  approximate numbers!!!!!!!!

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More yet

• You cannot express the number 1,234,567.8 as a
  float because it contains more than 7 digits. As
  a float it will be 1,234,568
• 0.1 cannot be expressed exactly-- it will
  be 0.099999

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Summary of data types
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Summary of data types
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The BLOB

• Binary Large Object
• Simply some data stored in the GDB as a long
  sequence of binary numbers.
• Such as
• Images
• Multimedia
• Code

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GDB and ArcCatalog

• View and modify contents of GDB

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GDB and ArcMAP

• Edit contents
• Full set of tools to edit
• simple features
• geometric networks
• topologies
• Editing a feature in a map topology or
  geodatabase topology with topology edit tools
  automatically updates the geometry of the shared
  parts of all features
• It then checks to see if you have violated any
  rules and tells you where the booboos are

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Summary
GDB
Feature Datasets Feature Classes Features