GIS Tutorial 1
Lecture 4
Geodatabases
Prepared by:
David Webb
With support from:
NSF DUE-0903270
in partnership with:
Geospatial Technician Education Through Virginia’s Community Colleges (GTEVCC)
Lecture 4
GEODATABASES
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The Geodatabase Poster
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Geodatabase

No more lost data!

Model of reality.

Contains the information needed to create a
map and answer a problem.

Schema already available.
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Geodatabase types
Manages features and tables inside a
database management system

File geodatabase




stores datasets in a folder of files
each dataset a file up to 1 TB in size
can be used across platforms
can be compressed and encrypted for read-only,
secure use
 ESRI’s recommended choice
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Geodatabase types

Personal geodatabase





stores datasets in a Microsoft Access .mdb file
storage sizes between 250 and 500 MB
limited to 2GB
only supported on Windows
ArcSDE geodatabase
 stores datasets in a number of optional DBMSs:
 IBM DB2, IBM Informix , Microsoft SQL
Server , Oracle, or PostgreSQL
 unlimited size and users
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New file geodatabase
ArcCatalog
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Import into geodatabase
Shapefile features
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Import into geodatabase

Tables
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Export from geodatabase
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Compact geodatabases

File and personal geodatabases
 Reduces size and improves performance
 Compact personal geodatabases > 250 MB.
 Geodatabases with frequent data entry, deletion,
or general editing
 Open geodatabases in ArcMap cannot be
compacted
 remove any layers with a source table or
feature class in that database from the TOC
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Compress geodatabases

File geodatabases
 Once compressed, a feature class or table is
read-only and cannot be edited
 Compression is ideally suited to mature datasets
that do not require further editing
 Compressed dataset can be uncompressed to
return it to its original, read-write format
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View geodatabases


Cannot identify names in Windows Explorer
Must use ArcCatalog
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Geodatabase Essentials
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Lecture 4
DATA MODELS
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Data Models

Download Models and copy appropriate
portions into your geodatabase.
 http://support.esri.com/en/downloads/datamodel

Base maps: http://resources.arcgis.com/content/localgovernment/basemaps

GDB Design Forms-Tutorial #3
 For large Projects and multiple entities
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Student Models

What data is required to answer the
questions…..Often driven by the limitations
on location.

Where to put a wind turbine in Roanoke
area?
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Wind Turbine

Wind power available

Elevation

Slope

Proximity to airports, roads, rivers,
populations

Ability to see from scenic locations
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Lecture 4
DATA TYPES
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Vector data

Map features
 Points, lines, polygons
 Shape Files

Feature attributes
 Every feature has attributes (e.g. name, area,
population) Tabular Data
Shape
Name
Class
Pop2000
State
Point
New York
City
8,008,278
NY
Point
Los Angeles
City
3,694,820
CA
Point
Chicago
City
2,896,016
IL
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Feature class

a collection of geographic features that
share the same geometry type (such as
point, line, or polygon) and the same
attribute fields for a common area. Streets,
well points, parcels, soil types, and census
tracts are examples of feature classes.
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Feature dataset

Use feature datasets to organize spatially
related feature classes into a common
dataset:
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Raster Data
Stored electronic image
or picture taken as an
aerial photograph or
satellite image
Composed of a rectangular array of
square cells, called pixels, with a number
in each cell representing the solid color fill
of that cell
http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/Supported_raste
r_dataset_file_formats/009t0000000q000000/
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Directly loadable data types


dBase (.dbf)
Text with comma (.csv) or tab-separated
values (.txt)

Microsoft Access (.mdb)

Microsoft Excel (.xls)
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Triangular irregular networks (TIN)
Vector based triangles: useful to create
slopes, contour intervals and other
elevation
data. Cannot be stored in a geodatabase.
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Terrain

TIN Based surface based on measurements
stored as features in a geodatabase.
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Lecture 4
TOPOLOGY
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Topology

Quality Assurance of Data
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Topology
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Topology tw_651
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