Fundamentals of

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451-610 Fundamentals of
GIS
Vector Map Operations and Manipulations,
Attribute Data Models Week 7 Abbas Rajabifard
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Overview

• Vector Map Operations and Manipulations-
  Generalisation Techniques
• Boundary Operation Single layer operations
• Boolean operations
• Multiple Layer Operations-Vertical Operations
• Examples of Vector Analysis
• Attribute Data Models
• GIS Conceptual Modeling

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Main Types of Data Structures
Spaghetti
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Vector Map Operations and Manipulations

•       Vector GIS operations can be summarised
  into two major operators or categories single
  layer and multiple layer operations.
•   Single layer operations refer to the
  procedures that apply to only one data layer at a
  time and multiple layer operations operate on
  multiple layers simultaneously.       
•  Operational procedures for manipulating map
  features on a single layer include boundary
  alteration and proximity analysis.
•  The second group of operations, multiple layer
  operations are fundamentally for analysis and
  spatial modeling..
•   

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Vector Map Operations and Manipulations
Generalisation Techniques

• Purposes of generalisation include to
•          Economise on the amount of data to be
  processed
•          To produce maps at various scales from
  the one source
•          The remove and modify features for
  effective visual communications
• Methods include
•           Simplification include generalise
•           Smoothing
•           Aggregation includes dissolve
  commands
•           Merge merge and mapjoin command.

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Vector Map Operations and Manipulations
Boundary Operation Single layer operations

•   Common procedures for manipulating feature
  boundaries include
• clipping, erasing, updating, splitting and
  dissolving
•   Most of these operations are only possible
  using topologically structure GISs.
•   They are also commonly called horizontal
  operations

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Vector Map Operations and Manipulations
Multiple Layer Operations-Vertical Operations

•    These operations can be divided into three
  broad categories
• Overlay, Proximity and Correlation Analysis.
•    Overlay analysis involved the logical
  connection and manipulation of spatial data on
  separate layers, to create combined spatial
  features according to logical conditions
  specified in Boolean analysis/algebra,
• The main difference of this operation with the
  same case in Raster is that rather than testing
  the Boolean condition for each raster cell, here
  we test for an entire polygon.

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         Boolean operations
Boolean operations in spatial analysis are
the simplest and perhaps the most often used set
of operations in GIS. Boolean operations
are based on the simplest level of data.
Each map overlay represents a binary map of only
two values 1 or 0 which
represent true or false yes or no or present or
absent. Boolean operations are
logical operations which are used to search data
bases for the co-occurrence of different
features. The primary Boolean operators
are NOT, AND, OR, and XOR.
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         Boolean operations
   
For A AND B, cells in both map overlay A and map
overlay B must be true (1). For A OR B,
cells in either map overlay A or map overlay B
must be true (1).     For A XOR B, cells must
be true either in map overlay A or map overlay B
but not both. The NOT operation simply changes
anything that is true to false and anything that
is false to true. This is called logical
negation.  
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Vector Map Operations and Manipulations
Multiple Layer Operations-Vertical Operations
Everything located within the boundaries of
the input layer is collected in the output layer
when merging multiple data layers.
The outer boundary of the output layer is
identical to that of the input layer.
 If the input is a point layer, the output layer
will contain only point features, although the
identify layer is always a polygon layer.

•    The most common of Overlay Analysis
  include
• Union, Intersection, Identity

•    Proximity analysis deals with operational
  procedures that are based on distance
  measurement between features on different
  layers.
• Distance between different types of spatial
  features is the primary element of proximity
  analysis.
• The proximity analysis is conducted to generate
  information about spatial properties used in
  other applications.
• The most fundamental functions of proximity
  analysis in GIS are
• Near operation , Pointdistance operation ,
  Buffering operation

•    Spatial correlation analysis is useful for
  revealing the relationships between features of
  different types.

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Examples of Vector Analysis
Vector Clip
Polygon option
Line option
Point option
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Examples of Vector Analysis
Vector Erase
Polygon option
Line option
Point option
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Examples of Vector Analysis
Split
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Examples of Vector Analysis
Append
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Examples of Vector Analysis
Eliminate
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Examples of Vector Analysis
Union
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Examples of Vector Analysis
Intersect
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Attribute Data Models
    Flat Files and Spreadsheets - A
flat file or spreadsheet is a simple method for
storing data. - All records in this
data base have the same number of "fields".
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Attribute Data Models
    Hierarchical Files -
Hierarchical files store data in more than one
type of record. - This method is
usually described as a "parent-child,
one-to-many" relationship. - One
field is key to all records, but data in one
record does not have to be repeated in another.

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Attribute Data Models
    Relational Files - Relational
files connect different files or tables
(relations) without using internal pointers or
keys. - Instead a common link of data
is used to join or associate records.
- One field is key to all records, but data in
one record does not have to be repeated in
another.
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Attribute Data Models
 

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GIS Conceptual Modeling
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Design and Implementation
User Views
User Needs
Conceptual Phase
Conceptual Modeling
Logical Model
Data Structure
Software Selection
Internal Model
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Successful GIS Implementation
Successful GIS implementation, in part, depend
upon understanding the real world in which the
organization operates how changes to real world
features affect the information needed by the
organization and how information systems are used
to support the functions that with such
changes. Todays successful GIS implementations
have integrated GIS into the daily operations of
many of their organizational functions and are
beginning to experience a variety of rewards and
challenges in the process.
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Successful GIS Implementation
A Municipal Government Example

• The physical components of a municipality are
• The Geographic coverage of its jurisdiction
• (political boundaries, natural features)
• The People within that area (residents, business
  people, visitors)
• The buildings and facilities that the People use
  
• (buildings, streets, utilities)
• The Business activities that influence the lives
  of the people and their physical environment
  (jobs, goods, services)
• The Land within the geographic coverage that
  supports the physical objects and activities of
  business and people.

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Municipal Government perception structure
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Another Example Private-Sector perception
structure
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The Four Elements of GIS in an Organizational
Context
1-The GIS Paradigm, A conceptual foundation for
using geographic information that provides a
common base of reference or focus for the other
three elements   The GIS paradigm defines how
spatial data are represented and managed,
determines the technology required to handle the
data, and subsequently defines the actions
required of the organization to achieve
successful implementation.
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The Four Elements of GIS in an Organizational
Context
2- Data Management Principles, the logical
structuring and management of databases A data
management strategy provides a set of guidelines
for structuring the collection, management, and
storage of data. The data management strategy
affect the allocation of staff and funds and
therefore impacts the organizations management
structure.  
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The Four Elements of GIS in an Organizational
Context
3- Technology, the effective combination of
various hardware and software components. Without
technology, implementation is not practical. -
Technology that is well aligned with the data and
organizational requirements will enable
successful system to be built. - Too much
emphasis on the technology (especially in the
early stages of GIS implementation), will lead to
expensive setbacks. - Technology selection should
be the result of careful analysis of user needs,
data management requirements and organizational
impact.
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The Four Elements of GIS in an Organizational
Context
4-Organizational Strategy/Setting, A management
environment that provides resources and enables
changes to be made for incorporating GIS
utilization throughout the organization. GIS is
not merely another software product purchased by
an organization to add to its list of softwares
to learn and use.
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The Four Elements of GIS in an Organizational
Context
These Four elements are tightly interconnected
(Huxhold and Levinsohn, 1995)
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1-The GIS Paradigm
The concepts and principles that are fundamental
to geography define the GIS Paradigm, and are
subsequently fundamental to successful
implementation of a GIS. There are

• Georeferencing, the process of locating features
  within a model of the surface of the earth.
•  
• Geocoding, the process of attaching a geographic
  reference to attributes (non-graphical) data.
•  
• Topology, the branch of mathematics that defines
  the relationships between features.

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3- Technology

• Candidate information technology for GIS
  implementation
• CAD,
• DBMS,
• Geoprocessing using,
• Remote sensing and image analysis,
• GPS,
• Multimedia (sound and video),
• Document imaging,
• Text processing,
• Network communications and electronic data
  interchange,
• etc.

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Nine Factors for Developing Conceptual Model in
GIS
1. Is the real world situation/phenomenon under
study simple or complex ? 2. Are the kinds of
entities used to describe the situation/phenomena
detailed or generalised ? 3. Is the data type
used to record attributes, Boolean, nominal,
ordinal, integer, real or topological ? 4. Do the
entities in the database represent objects that
can be described exactly, or are these objects
complex and possible somewhat vague ? Are their
properties exact, deterministic, or stochastic ?
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Nine Factors for Developing Conceptual Model in
GIS

• 5.  Do the database entities represent discrete
  physical things or continuous fields ?
• 6.  Are the attributes of database entities
  obtained by complete enumeration or sampling ?
• 7. Will the database be used for descriptive,
  administrative, or analytical purposes ?
• 8. Will the users require logical, empirical, or
  process-based models to derive new information
  from the database and hence make inferences about
  the real world ?
• 9.  Is the process under consideration static or
  dynamic ?

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Major Assignment
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Major Assignment
Option 1 GIS Conceptual Modelling Option 2
GIS Customisation (Avenue) and Model
Sensitivity Analysis.
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Major Assignment (option 1)
GIS Conceptual Modelling The purpose of this
project is to gain practical understanding of the
steps involved in the design of a GIS system
(conceptual modelling phase). Objectives You
will need to select an organisation/discipline of
their choice and develop a GIS conceptual model
based on the responsibilities of the organisation
in order to facilitate one of their daily
activities. However, the organisation that you
have chosen has been asked to design a GIS system
for the Tourism Industry in Victoria as well.
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Major Assignment (option 1)
The Managing team of the organisation therefore
asked you to advise on the design of the project
and also to develop the Conceptual Model for the
GIS system in such a way that the system also has
a module on the specific application of the
organisation. The organisation is going to
include all sorts of relevant data and
information (different layers of spatial data,
maps, photos, videos, ) in order to develop a
multi-media system for Tourists!
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GIS Conceptual Modelling
Project Name GIS for Victorian Tourism
Industry Project area/location under study
Victoria Users Victorian Tourists Specific
characteristics Multi Media Functionality
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GIS Conceptual Modelling
Tourists are usually looked for different
information such as -         Location of Bus,
Tram and Train stations/stops -        
Accommodations (Hotels, Motels, Hostels, etc.
with different price rang) -         Car
rentals -         Interest sites for
visit -         Routs to sites -        
Tourists Information Centers -        
Governments Offices/Building -        
Educational sites/campus -         Etc.
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GIS Conceptual Modelling
What do we need for GIS design? -         List of
users needs -         List of spatial data
features -         List of attributes for each
feature -         Details of spatial and
non-spatial data (spatial scale of map/s,
formats, types of map/s, etc. non-spatial text,
photos, video, etc.) -         Data collection
Methods -         Identifying the existing data
sources -
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GIS Conceptual Modelling
Classification and Features Coding (feature
classification super/main classes and
sub-classes) o       List of main classes
Building Road Infrastructures Utilities
etc. o       List of sub-classes for each main
class Transportation Railways and Roads
Roads main road, secondary Roads, streets,
allays, etc. o       Feature coding
Transportations TM1000, TS1000, TSt1000,
o       Feature Specification (Description,
color, layer, symbol, etc.) o      
Relationships           Justification
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Conceptual Model
Spatial Data
Main-Class
Sub-Class
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Thank you