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					Data Structures &
  GeoDatabase
                NEW!
• In 9.2 the GDBs have significantly
  changed
• Mostly for the better
• New names (file, personal, scaleable)
• Easier to move data between GDBs
• Do NOT have to specify the EXTENT
  of the GDB – a big problem in 9.1 and
  earlier.
    The Geodatabase

It is a single container for many
  feature classes (FC) (layers,
  {themes} of any feature class type)
Quite often the FCs are stored in
 Feature Datasets (FDS)
Shapes become Feature Classes (FC)
Data in a FDS can be topologically
 linked
          GeoDatabase Now
• Three flavors of GDB
  – File
  – Personal
  – Scalable (was called Enterprise)
• Supports a model of topologically
  integrated feature classes - 2D & 3D
• Supports Data Models -- ArcHydro
• Use can be simple or very complex!
• In some applications database designers
  will be needed to tune the database
  operation!
• Can use many different data structures
      The possibilities…




From ESRI’s course Learning ArcGIS Desktop
            GeoDatabase
• Three flavors of GDB
  – File
  – Personal
  – Scalable (was called Enterprise)
              File GDB

• Stored as folders in a file system.
• Can scale up to 1 TB in size.
• This option is the currently
  recommended GDB
• Only one user can edit at a time
• Is much faster than other flavors
            Personal GDB

• Stored within a Microsoft Access
  data file, which is limited in size to 2
  GB.
• One editor at a time
          Scaleable GDB
• Also called an ArcSDE Geodatabases
• Stored in a relational database using
  Oracle, Microsoft SQL Server, IBM
  DB2, or IBM Informix.
• These multi-user Geodatabases
  require the use of ArcSDE and can be
  unlimited in size and numbers of
  users.
• Much more complex and require
  professional computer types
          Scaleable GDB
• Also called an ArcSDE Geodatabases
• Stored in a relational database using
  Oracle, Microsoft SQL Server, IBM
  DB2, or IBM Informix.
ArcSDE = Spatial Database Engine
• These multi-user Geodatabases
  require the use of ArcSDE and can be
  unlimited in size and numbers of
  users.
• Much more complex and require
  professional computer types
        How do they look

• In ArcCatalog
• In Windows Explorer
 Catalog View
Views of GDB
           WE view
Views of GDB
            WE view




    Catalog View
        Advantages of GDBs
• Can be moved as one piece of data
  regardless of how much stuff is in it or
  where it is!
• Faster (particularly for File GDBs)
• Can use between layer topology for FC in a
  FDS
• Can actually get into the Personal GBD
  Access database and mess with it (but you
  had better know what you are doing!)
         Advantages of GDBs
 • Can be moved = the arrangement
TOPOLOGY? as one piece of data that
   regardless of how much stuff is in features
defines how point, line, and polygon it or
   where it is!
share coincident geometry.
 • Faster (particularly for File GDBs)
examples, between layer topology for FC in a
 • Can use
   FDS
•Fire hydrants must fall on water mains,
 • Can actually get into the Personal GBD
   Access soil polygons must share (but
•Adjacent database and mess with it theiryou
   had better know what you are doing!)
common boundaries.
  Geodatabase

                    Feature Classes
Feature Dataset




   Stand alone
  Feature Classes




     Source View
                         Line(arc)



                                  poly
                                  Anno
                                  Table

                                  point

                      }   Cover



               ArcCatalog view
Display view
                           These are in a
                           FDS and thus
                           valves can be
                           snapped (must
                           be actually) to
                           pipes
                      }   Cover



               ArcCatalog view
Display view
   More yet: Feature Class (FC)
• Conceptual representation of a category
  of geographic features.
• Includes point, line, poly & annotation
• When shapefiles are added to a GDB
  their computer representation is
  changed
• This is why you cannot drag and drop a
  shapefile into a GDB.
• You have to load it or Import it.
      Feature Dataset (FDS)
• 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
 GDB               Icons
            Feature Dataset




GDB table
 GDB               Icons
            Feature Dataset




GDB table
 GDB               Icons
            Feature Dataset




GDB table
Annotation
Vector data: Network
     Table 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
            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.
            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
        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
        Summary of data types

Name       Range,            Size     Applications
                            (bytes)
           length
Short      -32,768 to         2       No fractions
Integer    32,767
Long       -2,147,483,648     4       No fractions
           To
Integer
           2,147,483,647
Float      ~-34E-38 to        4       Fractional values
           ~1.2E38
         Summary of data types

Name        Range,         Size     Applications
                          (bytes)
            length
Double      ~ -2.2E-308     8       Fractions OK
            ~ 1.8E308
Text        <=64,000      varies Names etc.
            char

Date        mm/dd/yy        8       Date and time
            hh:mm:ss
          Creating a GDB

• In ArcCatalog!
• Point to where you want to put the
  new GDB
• Click New>Personal GDB
• Type in a new name
                Adding data
• In Catalog…
     Right click and select New
    • You get
            Copying data

• You can copy/paste data between
  GDBs
• OR
• You can import shapefiles, coverages,
  computer-aided drafting (CAD) data,
  and GeoDatabase FCs into a GDB
       Importing shapefiles

• feature class that's in another
  coordinate system.
  – You MUST project to the spatial
    definition of the GDB
  – Then right click on
    GDB and select
    Import --------- 
                Planning

• What is the problem?
• What data is needed (scale, extent,
  etc.0?
• What kinds of relationships are needed
  between FC?
• How will the data be organized (FDS)?
            SUMMARY

• The new GDB structure is much
  improved
• Easier to use
• 3 kinds
• Drop and drag between GDBs
• Extent does not have to be defined
  before creating

				
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posted:11/26/2011
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