The’Geodatabase’ - About...

ESSM/GEOG 462: Advanced GIS Ecosystem Science and Management | Texas A&M University (c) 2014, A. Michelle Lawing

The Geodatabase Chase T. Brooke Ecosystem Science and Management Texas A&M University College StaOon, TX 77843 [email protected]


EvoluOon of the acronym GIS


SpaOal Thinking

“IdenOfying, analyzing, and understanding the locaOon, scale, paZerns, and trends of the geographic and temporal relaOonships among data, phenomena, and issues.” -‐ Joseph Kerski


SpaOal Thinking

What is your definiOon of spaOal thinking?


What is a Geodatabase?

•  A spaOal relaOonal database management system that stores geographic and related data.

•  Central repository for spaOal data storage and management.


EvoluOon of database systems


Geometry Data Type

•  All 2D mapping can generally be accomplished with three geometry types

•  Points, polylines, and polygons


RelaOonships among features •  Topological

–  Determines adjacency and connecOvity among features –  Shared and coincident geometry types

•  SpaOal

•  Network –  Simple edges and juncOons –  Complex edges and juncOons

•  General


Topology


Geometric Network

•  The storage of network informaOon •  Several components –  Simple edges and juncOons –  Complex edges –  Complex juncOons


Geometric Networks

•  To build a network –  Sources and sinks –  ConnecOvity rules

•  Edge-‐juncOon rules •  Edge-‐edge rules

•  Perform a network analysis –  Trace –  Flow direcOon


The parts of a geodatabase

•  Geographic dataset –  Feature classes, a collecOon of features with the same type of geometry

–  RelaOonship classes, a table that stores the relaOonships between two feature classes

•  Object classes –  A feature class table –  A non-‐spaOal aZribute table


The parts of a geodatabase


Example Geodatabase


Making your own geodatabse

•  Design your data model –  Evaluate your data –  Define database structure –  Add data

•  Understand your spaOal reference –  Choose a coordinate system –  SpaOal domain –  Precision

•  Modify your spaOal domain if necessary


Benefits of using a geodatabase

•  Store a rich collecOon of spaOal data in a centralized locaOon

•  Apply sophisOcated rules and relaOonships to the data

•  Define advanced geospaOal relaOonal models (e.g., topologies, networks)

•  Maintain integrity of spaOal data with a consistent, accurate database


Benefits of using a geodatabase

•  Work within a mulOuser access and ediOng environment

•  Integrate spaOal data with other IT databases. •  Easily scale your storage •  Support custom features and behavior


Two types of Geodatabes in ArcGIS


Personal geodatabase

•  May be read by mulOple people •  Only edited by 1 person at a Ome •  Max size 2 GB •  Currently stores only vector data •  Raster stored as catalogs


MulO-‐user geodatabase

•  Suitable for large workgroups and enterprise GIS implementaOons

•  May be read and edited by mulOple users simultaneously

•  Requires ArcSDE and a DBMS •  Supports both raster and vector formats


A geodatabase extends a database

•  Provides the framework for defining and managing the GCS for a set of data

•  Models topologically integrated sets of feature

•  Defines general and arbitrary relaOonships between objects and features


A geodatabase extends a database

•  Enforces the integrity of aZributes through domains and validaOon rules

•  Binds the natural behavior of features to the tables that store features

•  Stores mulOple versions so that many users can edit the same data


SpaOal Query

•  What is a spaOal query?

•  Name three examples of a spaOal query


SpaOal Query OperaOons

•  Search –  ThemaOc search –  Search by region –  Search by classificaOon

•  LocaOon analysis –  Buffer –  Corridor –  Overlay



•  Terrain analysis –  Slope/aspect –  Catchment –  Drainage network

•  Flow analysis –  ConnecOvity –  Shortest path


SpaOal Query OperaOons •  DistribuOon

–  Change detecOon –  Proximity –  Nearest neighbor

•  SpaOal analysis/StaOsOcs –  PaZern –  Centrality –  AutocorrelaOon –  Indices of similarity –  Topology –  Hole descripOon



•  Measurements –  Distance –  Perimeter –  Shape –  Adjacency –  DirecOon


Architecture of a SpaOal Database


Core features of a DBMS

•  Persistence –  Some data are transient –  Some are persistent

•  TransacOons – Map a database from one consistent state to another –  All or abort – Many transacOons executed concurrently


Space Taxonomy

•  OrientaOon, DirecOon, Topological relaOonships (adjacent, next to, inside)

•  MulOtude of descripOons available to organize space


Data Model

•  Vector –  Points –  Polylines –  Polygons

•  Fields –  Raster, uniform grid imposed on underlying space –  TIN, triangulated irregular networks –  Contour lines –  Point grids


Data Model Example


Structured Query Language (SQL)

•  DeclaraOve language

•  User specifies the result

•  Example: Find all land parcels next to my house. SELECT M.address FROM land_parcel L, city_name M WHERE Adjacent (L,M) AND M.address = “MYHOUSE”


Types of queries

•  Range (select all points within 10 km of the city limits)

•  Join (combine two tables on a common aZribute)


SQL Examples

•  Join

•  SpaOal Join


File organizaOon and indices

Programmer’s Point of View Database Manager’s Point of View

Infinite

Infinite

Finite


Data mining

•  SystemaOc search of potenOally useful informaOon embedded in digital data

•  Hot topic of research inside and outside of academia

•  BIG DATA


Big Data Landscape


SpaOal data are Big Data


SpaOal data mining

•  Find paZerns in data with respect to geography

•  Not new in GIS, but methods are sOll in their infancy

•  Up to 80% of digital data is spaOal in nature!


SpaOal data mining

•  A spaOal database specialist can leverage experOse to… –  Design search algorithms to hand large amounts of data –  Extend SQL with “mining” methods

•  Random sampling commonly used in data mining

•  Because of spaOal autocorrelaOon, other techniques might need to be employed (spaOal staOsOcs)


SpaOal databases

•  Important for management of spaOal and related data

•  Important for the query of spaOal data to extract both spaOal and related data

The’Geodatabase’ - About...

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