APPLICATION OF REMOTE SENSING AND

GEOGRAPHICAL INFORMATION SYSTEM IN

CIVIL ENGINEERING

Date:

INSTRUCTORS

DR. MOHSIN SIDDIQUE

ASSIST. PROFESSOR

DEPARTMENT OF CIVIL ENGINEERING

� Remote Sensing (RS)

� Remotely sensing the usefulinformation of object (earth)

� Process of recording, measuring andinterpreting imagery and digitalrepresentations of energy patternsderived from noncontact sensor

systems

� Geographic Information

System (GIS)

� A system designed to capture,store, manipulate, analyze,manage, and present all types ofgeographically referenced data

Application of Remote Sensing and Geographical

Information System in Civil Engineering2

• G (Geography) - a particular form of Information System applied to geographical data (location, co-ordinates, maps etc..)

• I (Information) S (System) is a set of processes, executed on raw data, to produce information which will be useful in decision-making

• A series of steps from observation and collection of data through analysis to information (Data Handling)

• The DATA into INFORMATION PATHWAY ( Data = Facts; Information =

Facts with Meaning)

Basic definition of GIS3

• GIS as a Toolbox

�

• Usage of GIS for Mapping

• Static vs. Interactive Maps

• GIS as Interactive Cartography

• The Analysis Distinction - Query to Analysis

•

• GIS as an Approach to Science

• GIS as a Discipline

Basic Usage of GIS4

Origin of GIS

Computer Aided

Cartography

(CAC)

Remote Sensing

(RS)

Computer Aided Design/

Drafting

(CAD)

Database

Management

Systems

(DBMS)

GISIntegrated Technologies

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Geographic Information System (GIS)6

� GISs are simultaneously the telescope, the microscope, the computer, and the

Xerox machine of regional analysis and synthesis of spatial data. (Ron Abler,1988)

� “A powerful set of tools for storing and retrieving at will, transforming and

displaying spatial data from the real world for a particular set of purposes“(Burrough, 1986, p. 6).

� “Automated systems for the capture, storage, retrieval, analysis, and display of

spatial data." (Clarke, 1995, p. 13).

� "An information system that is designed to work with data referenced by spatial

or geographic coordinates. In other words, a GIS is both a database system with

specific capabilities for spatially-referenced data, as well as a set of operations

for working with the data" (Star and Estes, 1990, p. 2).

� "A geographic information system is a special case of information systems where

the database consists of observations on spatially distributed features, activities

or events, which are definable in space as points, lines, or areas. A geographic

information system manipulates data about these points, lines, and areas to

retrieve data for ad hoc queries and analyses" (Dueker, 1979, p 106).

What Is GIS - a Brief Introduction7

What Is GIS - a Brief Introduction

� Different mapping systems:

� Electronic atlases

� Thematic mapping systems

� Street-based mapping systems

� GIS: all these things + much more

� analysis, import/export, combination of different data, dynamic map update, etc

“A system of hardware, software, data,people, organizations and institutionalarrangements for collecting, storing,analyzing, and disseminating informationabout areas of the earth (Dueker and Kjerne,1989)

Use of geography to integrate

information from different sources

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� Information

� Remote sensing data

� Geographic data

� Hardware

� Computer

� Digitizer

� Scanner

� Printer/Plotter

Tools for GIS9

� Software

�Desktop GIS

� Internet GIS

�CAD Software

�Database Software

�Multimedia (photos, videos, 3D models)

� Geographic data – 80% of government data collected is associated withsome location in space

� Information - attributes, or the characteristics (data), can be used tosymbolize and provide further insight into a given location

� System – a seamless operation linking the information to the geography –which requires hardware, networks, software, data, and operationalprocedures

…not just software! …not just for making maps!

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GIS Functional Elements

1. Acquisition

� digitizing, editing, topology building, projection transformation, format conversion, attribute assignment etc.

2. Pre-Processing

� Analogue to digital

� Conversion of units

3. Management

� Data archival, databases (hierarchical model, networking model, relational databases etc.)

4. Manipulation and Analysis

� Buffering, overlay, connectivity operations etc.

5. Output (Product Generation)

� Thematic maps, 3D birds eye view, scaled maps etc

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Why a GIS

� Old Records/maps are poorly maintained

� Poorly Updated

� Inaccurate

� No Sharing

� No data retrieval service for maps

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Benefits of GIS

Once a GIS is implemented, following benefits are expected:

� Better Maintained data

� Standard format

� Easy revision,

� Easy updation

� Easy Units conversion

� Easy to share

� Easier to search, analyze and represent

� Many value added products

� Enhance productivity of staff

� Time and Money saved

� Better Decision making

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GIS as a Multi-Disciplinary Science

Combination of following traditional sciences

� Geography

� Statistics

� Cartography

� Remote Sensing

� Photogrammetry

� Computer Science

� Operation Research

� Mathematics

� Surveying

� Civil Engineering

� Geodesy

� Urban Planning

� Environmental Engineering, etc.

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Alternate Names of GIS

� Land Information System (LIS)

� AM/FM-Automated Mapping and Facilities Management

� Environmental Information System (EIS)

� Resource Information System (RIS)

GIS Is now becoming independent DISCIPLINE in the name of

GEOINFORMATICS, or GEOSPATIAL INFORMATION SYSTEM.

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Areas of GIS Applications

� Facilities Management � e.g. PTCL, SNGPL, Irrigation, WASA, for: locating underground pipes and cables)

� Environmental and Natural Resource management � suitable lands for crops, management of forests, EIA, Disaster Management etc.

� Street Network� Car Navigation, locating houses and streets, rescue services etc.

� Planning and Engineering � DAMS, Power Projects, urban planning, regional planning

� Land Information System � Board of Revenue, taxation, zoning, land acquisition.

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GIS and DSS

� GIS is usually an important component of modern Decision Support Systems (DSS)

� DSS components:

� Data Base

� Statistical Analysis

� Numerical Model

� Input and output facility

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USE OF GIS as DSS

Driving Forces: Population,

Health, Wealth, Technology,

Politics, Economic

Analysis and Assessment by GIS

Decision Making: Planning and Management

Human Impacts: Development, Urbanization, Industrialization,

Construction, Energy Use

Environmental Change: Land use Change,

Change of Life Style, Land Degradation,

Pollution, Climate Change

Monitoring By Remote Sensing

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GIS Software

� ESRI: ARC/INFO, ARC VIEW, ARC GIS

� Intergraph: MGE

� Grass Information Centre: GRASS*

� Clark University: IDRISI

� AUTODESK: ARC MAP

� ILWIS: Integrated Land and Water Information System.

http://grass.osgeo.org/ http://www.clarklabs.org/products/idrisi-taiga.cfm

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� Advantages of GIS� Exploring both geographical and thematic components of data in a holistic way

� Stresses geographical aspects of a research question

� Allows handling and exploration of large volumes of data

� Allows integration of data from widely disparate sources

� Allows analysis of data to explicitly incorporate location

� Allows a wide variety of forms of visualisation

� Limitations of GIS� Data are expensive

� Learning curve on GIS software can be long

� Shows spatial relationships but does not provide absolute solutions

� Origins in the Earth sciences and computer science. Solutions may not be appropriate for humanities research

Advantages and Disadvantages of GIS19

Basics of GIS

Lets starts20

Basic Geographical Concepts21

One of the most commonproducts of a GIS is a map

Global to local

Spatial Objects

Points

Line/node

Polygon/chain

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Basic Geographical Concepts

� Spatial Object: Delimited Geographical areas, with a number ofdifferent kind of associated attributes

� Point: A spatial object with no area. A key attribute is its geodeticlocation. Many Attributes can be associated with a Point

� Line: A spatial object, made up of a connected sequence of points. Lineshave no width, thus a specified location will be on one side of a line orother, but never on a line.

� Nodes: Special kinds of points showing start, end and junction of linesegments.

� Polygon: A closed Area. Simple Polygons are undivided areas, whilecomplex polygons are divided into areas of different characteristics.

� Chains: Special kinds of line segments, which corresponds to a portionof the bounding edge of polygon.

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Basic Geographical Concepts

Parcels: The allotment of some amount by dividing something

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� Scale

� Ratio of distance on map (or image) to their true length on the earth’ssurface

� Large Scale: A scale is relatively large, if the area or length representedon map (or image) is large

� Small Scale: A scale is relatively small, if the area or length representedon map (or image) is small

� e.g.

1:10,000 is large scale as compared to 1:100,000.

� Resolution

� Refers to minimum size of the element which we can distinguish on a map.

� For Raster Maps, it is size of cell

� For Maps, it is

= (Area/No of elements)^0.5

� Higher the resolution, more information are available.

� RESEL=Resolution Element

Basic Geographical Concepts24

Basic Geographical Concepts25

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� Attributes

� Pertinent (important) information of geospatial data.

e.g. if a line is representing a road through geographic data (Lat., Long. orEasting , Northing), then its helping information such as width, condition,name, metaled or un-metaled etc. are its attributes.

� Only those attributes should be selected/acquired which might berequired in the analysis.

Basic Geographical Concepts26

� A GIS stores information about the world as a collection of thematic layers that can be linked together by geography

� The basic data type in a GIS reflects traditional data found on a map

� Spatial data

� describes the absolute and relative location of geographic features.

� Attribute data

� describes characteristics of the spatial features. These characteristics can be quantitative and/or qualitative in nature. Attribute data is often referred to as tabular data.

GIS data model (Database management systems-DBMS )

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� Three basic types of spatial data models have evolved for storing geographic data digitally. These are referred to as:

� Raster;

� Vector;

� Image.

SPATIAL DATA MODELS

Image data utilizes techniques very similar to raster data, however typically lacks the

internal formats required for analysis and modeling of the data

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� Raster data models incorporate the use of a grid-cell data structure where the geographic area is divided into cells identified by row and column.

� For digital representations of aerial photographs, satellite images, scanned paper maps, and other applications with very detailed images.

Raster data models

� A raster data structure is in fact a matrix where any coordinate can be quickly

calculated if the origin point is known, and the size of the grid cells is known

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� Vector storage implies the use of vectors (directional lines) to represent ageographic feature. Vector data is characterized by the use of sequentialpoints or vertices to define a linear segment. Each vertex consists of an Xcoordinate and a Y coordinate.

� Vector lines are often referred to as arcs and consist of a string of verticesterminated by a node.

Vector Data models30

Geometry and Topology of Vector data31

Topology is a mathematical concept that has its basis in the principles of feature adjacency and connectivity

The most popular method of retaining spatial relationships among features is to

explicitly record adjacency information in what is known as the topologic data

model

The topologic data structure is often referred to as an intelligent data structure

� Image data is typically used in GIS systems as background display data (if the image has been rectified and georeferenced); or as a graphic attribute

� Image data must be converted into a raster format (and perhaps vector) to be used analytically with the GIS

Image Data models32

� Attribute data refers to pertinent information attached to each geo-spatialdata. A variety of different database models exist for the storage andmanagement of attribute data. The most common are:

1. Tabular (Outdates in GIS !), 2. Hierarchial

3. Network 3. Relational

5. Object Oriented

The hierarchical database organizes data in a tree structure. Data isstructured downward in a hierarchy of tables.

The network database organizes data in a network or plex structure. Anycolumn in a plex structure can be linked to any other

The object-oriented database model manages data through objects.

An object is a collection of data elements and operations that together areconsidered a single entity.

The object-oriented database is a relatively new model. This approach hasthe attraction that querying is very natural, as features can be bundledtogether with attributes at the database administrator's discretion.

Attribute data models33

� A separate data model is used to store and maintain attribute data for GIS

software.

� These data models may exist internally within the GIS software, or may be reflected in external commercial Database Management Software (DBMS)

Note

Attribute database models

Examples of object-oriented data model

Hierarchial and network database models have not gained any noticeable acceptance for use within GIS

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� A relational database organizes data in tables. Each table, is identified by a unique table name, and is organized by rows and columns. Each column within a table also has a unique name.

Attribute data models

UNIQUE

STAND

NUMBER

DOMINANT

COVER

GROUP

AVG. TREE

HEIGHT

STAND SITE

INDEX

STAND AGE

001 DEC 3 G 100

002 DEC-CON 4 M 80

003 DEC-CON 4 M 60

004 CON 4 G 120

The relational database model is the most widely accepted for managing

the attributes of geographic data.

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Basic linkages between a vector spatial data (topologic model) and attributes maintained in a relational database file (From Berry)

Relational Attribute model37

� Attribute data consists of qualitative or quantitative data. Qualitative data

specify the types of object, while quantitative data can be categorized into ratio data, data measured in relation to a zero starting point; interval data, data arranged into classes; and ordinal data, which specify quality by using text.

Relational Attribute model38

� ‘Which is best? depends in 4 issues

� coordinate precision

� speed of analytical processing

� mass storage requirements

� characteristics of phenomena

Choice between raster and vector data

Choice between raster and vector data

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� Data on different themes are stored in separate “layers”

� As each layer is geo-referenced layers from different sources can easily beintegrated using location

� This can be used to build up complex models of the real world from widelydisparate sources

Spatial Data Layers (layers)

The definition of data layers is fully dependent

on the area of interest and the priority needs

of the GIS. Layer definitions can vary greatly

depending on the intended needs of the GIS

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� As data acquisition or data input of geospatial data in digital format is most expensive (about 80% of the total GIS project cost) and procedures are time consuming in GIS

Required Data Sources for GIS41

� The geographic location of each cell is implied by its position in the cellmatrix. Accordingly, other than an origin point, e.g. bottom left corner, nogeographic coordinates are stored.

� Due to the nature of the data storage technique data analysis is usually easyto program and quick to perform.

� The inherent nature of raster maps, e.g. one attribute maps, is ideally suitedfor mathematical modeling and quantitative analysis.

� Discrete data, e.g. forestry stands, is accommodated equally well ascontinuous data, e.g. elevation data, and facilitates the integrating of the twodata types.

� Grid-cell systems are very compatible with raster-based output devices, e.g.electrostatic plotters, graphic terminals.

Advantages of Raster data42

� The cell size determines the resolution at which the data is represented.;

� It is especially difficult to adequately represent linear features depending onthe cell resolution. Accordingly, network linkages are difficult to establish.

� Processing of associated attribute data may be cumbersome if large amountsof data exists. Raster maps inherently reflect only one attribute orcharacteristic for an area.

� Since most input data is in vector form, data must undergo vector-to-rasterconversion. Besides increased processing requirements this may introduce dataintegrity concerns due to generalization and choice of inappropriate cell size.

� Most output maps from grid-cell systems do not conform to high-qualitycartographic needs.

Disadvantages of Raster data43

� Data can be represented at its original resolution and form withoutgeneralization.

� Graphic output is usually more aesthetically pleasing (traditional cartographicrepresentation);

� Since most data, e.g. hard copy maps, is in vector form no data conversion isrequired.

� Accurate geographic location of data is maintained.

� Allows for efficient encoding of topology, and as a result more efficientoperations that require topological information, e.g. proximity, networkanalysis.

Advantages of Vector data44

� The location of each vertex needs to be stored explicitly.

� For effective analysis, vector data must be converted into a topologicalstructure. This is often processing intensive and usually requires extensive datacleaning. As well, topology is static, and any updating or editing of the vectordata requires re-building of the topology.

� Algorithms for manipulative and analysis functions are complex and may beprocessing intensive. Often, this inherently limits the functionality for largedata sets, e.g. a large number of features.

� Continuous data, such as elevation data, is not effectively represented invector form. Usually substantial data generalization or interpolation isrequired for these data layers.

� Spatial analysis and filtering within polygons is impossible

Disadvantages of Vector data45

Comparison b/w raster and vector data 46

Assignment47

Comments….

Questions….

Suggestions….

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I am greatly thankful to all the information sources(regarding remote sensing and GIS) on internet that Iaccessed and utilized for the preparation of presentlecture.

Thank you !