Download - GIS Data Modeling and Database Design (2014)
-
8/10/2019 GIS Data Modeling and Database Design (2014)
1/19
Modeling and Representing
Geographic Situation andGIS Database Design
Nama Raj Budhathoki, Ph.D.
-
8/10/2019 GIS Data Modeling and Database Design (2014)
2/19
Nama Raj Budhathoki Apex GIS course - 2014
2
Model can be in different forms
-
8/10/2019 GIS Data Modeling and Database Design (2014)
3/19
Nama Raj Budhathoki Apex GIS course - 2014
3
Dictionary meaning of Model
Miniature representation of an object,
system, process or phenomena so thatits certain aspects of interest can be
analyzed/studied
Can be picture, mathematical, physical,
diagram or other
-
8/10/2019 GIS Data Modeling and Database Design (2014)
4/19
Nama Raj Budhathoki Apex GIS course - 2014
4
Geospatial Data Modeling
Process of extracting and representing
geospatial objects or phenomena in
relation to their location in geographic
space and time
This process influences the type of
questions a GIS can answer
-
8/10/2019 GIS Data Modeling and Database Design (2014)
5/19
Nama Raj Budhathoki Apex GIS course - 2014
5
Paper Map as a Model of Real World
Data capture
Representation
Visualization
-
8/10/2019 GIS Data Modeling and Database Design (2014)
6/19
Nama Raj Budhathoki Apex GIS course - 2014
6
But!..Paper Map is an inefficient
model of Real World
Difficult to change andanalyze information
Fixed scale Require large storage space
High back up, production,reproduction and transfercost
Features in map fade overtime and use
Shrinkage bringsmeasurement inaccuracies
-
8/10/2019 GIS Data Modeling and Database Design (2014)
7/19
-
8/10/2019 GIS Data Modeling and Database Design (2014)
8/19
Nama Raj Budhathoki Apex GIS course - 2014
8
How can we represent such a
complex world in the computer?
-
8/10/2019 GIS Data Modeling and Database Design (2014)
9/19
Nama Raj Budhathoki Apex GIS course - 2014
9
Two Views
Continuous phenomena(Elevation, temperature,
pollution etc.)
Discrete Objects withclear boundary, shape
and size (Land parcels,
buildings, roads etc.)
-
8/10/2019 GIS Data Modeling and Database Design (2014)
10/19
Nama Raj Budhathoki Apex GIS course - 2014
10
Geospatial Data Models
We use different models to
represent two views ofgeospatial phenomena: Feature
(vector)for discrete objects and
Field (Raster) for continuous
phenomena
-
8/10/2019 GIS Data Modeling and Database Design (2014)
11/19
Nama Raj Budhathoki Apex GIS course - 2014
11
Stages of Geospatial Data Modeling
Representation
in the computer
Extraction ofthe real world
Realworld
Human World (Real World)
Computer World (Virtual World)(0s and 1s)
-
8/10/2019 GIS Data Modeling and Database Design (2014)
12/19
Nama Raj Budhathoki Apex GIS course - 2014
12
Different Levels of Data Modeling
Conceptual Modeling
Physical Modeling
Logical Modeling
Realworld
What to
extract?
How to represent andstore in computer?
-
8/10/2019 GIS Data Modeling and Database Design (2014)
13/19
Nama Raj Budhathoki Apex GIS course - 2014
13
Conceptual Data Model
Certain concept (domain) is used toselectively extract the real world from its
infinite complexity.Consists of the following steps (Zeiler1999):
Model the user and use view
Define entities and their relationships
Identify representation of entities
-
8/10/2019 GIS Data Modeling and Database Design (2014)
14/19
Nama Raj Budhathoki Apex GIS course - 2014
14
Conceptual Date Model:Model use and users view
Identify the functions GIS is to support
eg.Land Use Planning
Identify the data required to support tothese functions
eg. Land Records, Environmental data,
Transportation data
-
8/10/2019 GIS Data Modeling and Database Design (2014)
15/19
Nama Raj Budhathoki Apex GIS course - 2014
15
Conceptual Model:Define and describe entities
Identify entities
Entities are distinguishable objects; Something about which data is kept
Describe entities
Attributes associated with an entity
Key Attribute - uniquely identify an entity
-
8/10/2019 GIS Data Modeling and Database Design (2014)
16/19
Nama Raj Budhathoki Apex GIS course - 2014
16
Conceptual Model:Identify relationships and attributes
Identify and describe relationships
among these entities
One-to-One (1:1)
One-to-Many (1:N)
Many-to-Many (N:M)
Document the entities andrelationships in diagram (ERD)
-
8/10/2019 GIS Data Modeling and Database Design (2014)
17/19
Nama Raj Budhathoki Apex GIS course - 2014
17
Diagrammatic Example of Land
Records
More on Next Week
-
8/10/2019 GIS Data Modeling and Database Design (2014)
18/19
Nama Raj Budhathoki Apex GIS course - 2014
18
Conceptual Model:Identify representation of entities
Point
LineArea
Raster
Image Surface
Object
Discrete Features
Continuous Phenomena
Terrain
Non-geographic entity
-
8/10/2019 GIS Data Modeling and Database Design (2014)
19/19
Nama Raj Budhathoki Apex GIS course - 2014
19
Summary
Data capture
Data storage
and management
Data Visualization
Database