database

basesprocketData Management

Oct 31, 2013 (3 years and 8 months ago)

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Introduction to the


Geodatabase






What is a Geodatabase?



What are feature classes and feature datasets?



What are domains



Design a personal Geodatabase



Import data to a Geodatabase


What is a Geodatabase?



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

A relational database that contain
geographic information





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


Feature classes…..





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.



Feature datasets…..

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




Personal vs. Multiuser 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



Why Geodatabase?



Dynamic Geocoding




Annotation subclasses




Subtypes within Feature classes




Coded attribute and range domains




Improved topology and editing



More advantages…..

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

Confused?

-
The geodatabase may
seem complicated…..

-

Geodatabases can be created and
managed easily using the standard
tools in ArcCatalog


-

ArcMap and ArcToolbox provides
tools to work with geodatabases


Geodatabases in ArcGIS




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




Creating a Geodatabase

Think before you create


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?



Create a new Geodatabase


in ArcCatalog




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





Migrating existing data into


the Geodatabase



Importing existing data



In ArcCatalog or
ArcToolbox



Tools and wizards are
available



Works with coverages,
shapefiles, tables, CAD
etc.








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







Coordinate Domains

Lost data

Large area

Smaller precision (1,000)

Small area larger precision (100,000)

(0,0)

Y

X

Max X and Y is 2.14 billion

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

What is max/min X and Y on the map?

Max X and Y

Min X and Y

Setting X/Y Domain Precision


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)

1000

(0,0)

Y

X

Max X and Y is 2.14 billion

Most of the data is here in the database


Large expansion options to the north and east

Coordinate Domains

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 10
9
) / (1000 x 2) =
X min


2,401,450


1,070,000 = 1,331,450



(MinY + MaxY)/2


(2.14 x 10
9
) / (1000 x 2) =
Y min


1,800,275


1,070,000 = 730,275

(MinX + MaxX)/2
+

(2.14 x 10
9
) / (1000 x 2) =
X max


2,401,450
+

1,070,000 = 3,471,450



(MinY + MaxY)/2
+

(2.14 x 10
9
) / (1000 x 2) =
Y max


1,800,275
+

1,070,000 = 2,870,275

Min X ~ 2,145,320

Max X ~ 2,657,580

Min Y ~ 1,632,610

Max Y ~ 1,967,940

Precision 1000


Min X = 1,331,450

Max X = 3,471,450

Min Y = 730,275

Max Y = 2,870,275

Precision 1000


Default x/y domain

Shifted x/y domain

Coordinate Domains Calculations

(0,0)

Y

X

Max X and Y is 2.14 billion

Most of the data is here in the database


Large expansion options in all directions

Coordinate Domains

The shifted x/y domain allows for


editing within this window

Max X, Max Y

Min X, Min Y

Why create Feature Datsets?



Data organization



Topology rules



Shared boundaries



Geometric networks

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

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)


Questions?