GEOGRAPHICAL

INFORMATION SYSTEM

An organized collection of computer hardware, software, Geographical data and personnel

designed to efficiently capture, store, update, manipulate, analyze & display all forms of

Geographically referenced information

GEOGRAPHIC INFORMATION SYSTEM

What is a GIS?

Geographic Information System

• “There are as many definitions as there are disciplines using a GIS”(Huxhold, 1991)

WHAT IS A GIS ?GEOGRAPHIC implies that locations of the data items are known, or can

be calculated, in terms of Geographic coordinates (Latitude, Longitude)

INFORMATION implies that the data in a GIS are organized to yield useful knowledge, often as coloured maps and images, but also as statistical graphics, tables, and various on-screen responses to interactive queries.

SYSTEM implies that a GIS is made up from several inter-related and linked components with different functions. Thus, GIS have functional capabilities for data capture, input, manipulation, transformation, visualization, combinations, query, analysis, modelling and output.

What is a GIS?A GIS is a database management system forspatially distributed features and the associated attributes.

• Spatial data capture• Management• Analysis• Display• Decision making• Research

GEOSPATIALDATA

USERS

COMPUTER SYSTEM

KEY COMPONENTS OF GISKEY COMPONENTS OF GIS

Hardware&SoftwareCapture, Storage, processing

Analysis, Display etc.,

Maps, Aerial photographs, SatelliteImages, Statistic Tables etc,

Design of Standards, Updating, Analysis and Implementations

*COMPUTERISED CARTOGRAPHY-- performing cartographic functions by means computer hardware and software

*CARTOGRAPHY -- art and science of map making

A map represents geographic features or other spatial phenomena by graphically conveying information aboutlocations and attributes

*MAP

•Map(graphic) information * only graphic data is available and retrieval * networks are not defined.•Map publication * spatial relationship not defined

Computer Assisted Mapping

INTRODUCTION

PERSONNEL

ROLE OF LOCATION - ORGANISATION

VIEWERS USERS DOERS

BASIC FUNCTIONS OF GISBASIC FUNCTIONS OF GIS

WHAT IS IT….?WHAT IS IT….?(LOCATIONS)(LOCATIONS)

JFM AREAJFM AREA

(X,Y)

WHERE IS IT ….?WHERE IS IT ….?(CONDITIONS)(CONDITIONS)

WITHIN THE WITHIN THE FOREST BLOCK FOREST BLOCK

HOW HAS IT HOW HAS IT CHANGED …?CHANGED …?(TRENDS)(TRENDS)

IMPROVEMENT INIMPROVEMENT INFOREST GROWTHFOREST GROWTHIN FIVE YEARSIN FIVE YEARS

WHICH DATA AREWHICH DATA ARERELATED ….?RELATED ….?(PATTERNS)(PATTERNS)

NEARESTNEARESTJFM VILLAGEJFM VILLAGE

WHAT IF….?WHAT IF….?(MODELS)(MODELS)

FINDING SOLUTIONS TO FINDING SOLUTIONS TO THE FORTH QUESTIONSTHE FORTH QUESTIONS

DATA

ATTRIBUTE DATA

SPATIAL DATA

SPATIAL DATARaster

Vector

DATA MODEL AND STRUCTUREDATA MODEL AND STRUCTURE

RASTER MODELRASTER MODEL VECTOR MODELVECTOR MODEL

ADVANTAGES OF VECTOR MODELADVANTAGES OF VECTOR MODEL

• PRECISE EXPRESSIONPRECISE EXPRESSION• LESS DATA VOLUMELESS DATA VOLUME• FULL TOPOLOGYFULL TOPOLOGY• FAST RETRIEVALFAST RETRIEVAL• FAST CONVERSIONFAST CONVERSION

ADVANTAGES OF RASTER MODELADVANTAGES OF RASTER MODEL

• SIMPLE DATA STRUCTURESIMPLE DATA STRUCTURE• EASY FOR OVERLAY AND EASY FOR OVERLAY AND MODELLINGMODELLING• SUITABLE FOR 3D DISPLAYSUITABLE FOR 3D DISPLAY• INTEGRATION OF IMAGE DATAINTEGRATION OF IMAGE DATA• AUTOMATED DATA CAPTUREAUTOMATED DATA CAPTURE

DISADVANTAGES OF VECTOR MODELDISADVANTAGES OF VECTOR MODEL

• COMPLICATED STRUCTURECOMPLICATED STRUCTURE• DIFFICULTY IN OVERLAYDIFFICULTY IN OVERLAY• DIFFICULTY IN UPDATINGDIFFICULTY IN UPDATING• EXPENSIVE DATA CAPTUREEXPENSIVE DATA CAPTURE

DISADVANTAGES OF RASTER MODELDISADVANTAGES OF RASTER MODEL

• LARGE DATA VOLUMELARGE DATA VOLUME• LOW PRECISIONLOW PRECISION• DIFFICULTY IN NETWORK DIFFICULTY IN NETWORK ANAYLYSISANAYLYSIS• SLOW CONVERSIONSLOW CONVERSION

What Data is in Your GIS?

• What features do you map?

• What attributes do you need to collect data on?

• What attribute values can you give the attribute?

Point Features

Spatially distributed entities, activities orevents

• Points have a single geographic coordinate such as:– Tree– Traffic accident– Lamp post

Line Features

Spatially distributed entities, activities orevents

• Lines (Arcs) are a series of geographic coordinates joined to form a line such as:– Road– Stream – Railway

Area FeaturesSpatially distributed entities, activities orevents

• Areas (Polygons) are a series of geographic coordinates joined together to form a boundary such as: – Lake– Soil types

Automated Mapping/Facility Management

Graphic files Non-graphic files

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efined

Attribute dataAttributes can be numeric or alfanumeric

data that is assigned to a point, line or area spatial features

Example Attributes…

Stand ID, Compartment no,Vegetation type, Name of the Forest Block,Type of Road,VSS code etc.,

Data Capture Sources

• Digitizing from paper maps

• Scanning

• Traditional surveying techniques

• Paper records & field notes

• Photogrammetry

• Remote sensing

• GPS

GIS Data Storage

There are two main types of data in a GISdatabase

• Cartographic - observations on spatially distributed features, activities, or events, which are definable as:– Points– Lines (Arcs)– Areas (Polygons)

GIS Data Storage

• Non-Cartographic - descriptive information in a database about the cartographic features located on a map.– Attributes– Attribute Values

Attributes

Description or characteristic of a feature

• Possible attributes for the feature Tree– Height– Diameter– Species– Condition– Age

Attribute Values

The value given to an attribute

• Possible values for the attributes of a Tree feature– Height = 15m– Diameter = 0.75m– Species = Oak– Condition = Good– Age = 8 years

DATA STRUCTURES - POINT, LINE, POLYGON, THEME

PERSONNEL - VIEWERS, USERS, DOERSROLE OF LOCATION - ORGANISATION

DATA COLLECTION - SOURCES OF DATA - CONVERSIONTO DIGITAL FORMAT, PROCESSING,STORAGE, UPDATION

ANALYSIS - OVERLAY, BUFFER, DISSOLVE, LINKING WITHRDBMS

CODING - NEED FOR CODE - LOGISTICS IN CODING

OUTPUTS - HARD COPIES, SOFTWARES, MODELS

ADVANTAGES OF GIS

Type of Errors

• Dangle Node • Undershoot• Overshoot• Missing Labels • Duplicate labels • Pseudo nodes • Unclosed polygon• Incorrect user ID to the features

Types of Attribute ValuesThere are a number of different types ofattribute values

Feature Attribute Attribute Values

Character Pole Pole ID ABC123

Numeric Pole Height 15m

Menu Pole Condition GoodAveragePoor

Date Pole Date User generatedAuto generated

Time Pole Time User generatedAuto generated

BASIC FUNCTIONS OF GISBASIC FUNCTIONS OF GIS

• DATA AQUISITION AND DATA AQUISITION AND PREPROCESSINGPREPROCESSING

DIGITIZINGDIGITIZING EDITINGEDITING

TOPOLOGY BUILDINGTOPOLOGY BUILDING

PROJECTIONPROJECTION ATTRIBUTIONATTRIBUTION

TOPOLOGY

• Topology mathematical representation of geographic features(arcs, nodes, polygons and points)

• When topology is built,it creates spatial relationship among the features

• Topology can be very important for certain types of analysis.

TOPOLOGIC DATA ELEMENTS

Node

Line (Arc)

Area(polygon)

Nodes: defines beginning and end of the lineLine: defines roads,utilities,boundaries,etc.,Areas: administrative boundaries, forest block,JFM areas,lakes

Supports spatial analysis

Supports network analysis

Supports map publication

LOGISTICS IN CODING

CODING

NEED FOR CODE

JFM_CODECOMPT_CODEDDRB_CODE

PROJECTION

GEOREFERENCING/GEOCODING SPATIAL DATA

Transforming three-dimensional space onto a two-demensionalmap is called ‘projection’ orProjection is a mathematical expression which convert data froma geographical location(lat & long) on sphere or spheroid to arepresentative location on a flat surface.

This much earth surfacehas to fit onto this muchmap surface

Projection Plane

*Conformal projections*Equal-area projections*Equidistant projections

WHY GIS ?

• To inventory and monitor resources

• To test the sensitivity of our analysis assumptions

• To simulate potential impacts of management alternatives

• To make the map the 2nd time, the 50th time, the 100th time...

Uses of a GIS

• Mapping geographical characteristics for analysis

• Modeling alternative processes for management plans

• Managing a utility’s assets

• Monitoring changes in environmental factors

Integration of Data

GIS data

• A GIS allows integration of data collected: – At different times– At different scales– Using various methods of capture

GIS Data Analysis

• A GIS identifies relationships among features in the database

• Provide answers to queries that are spatial (geographic)

THEMATIC OVERLAYTHEMATIC OVERLAY

1. TOPOGRAPHY1. TOPOGRAPHY

2. BOUNDARIES2. BOUNDARIES

3. VEGETATION3. VEGETATION

4. ROADS4. ROADS

5. RIVERS5. RIVERS

6. SOILS6. SOILS

Query and Analysis

Data Query Output

Veg_type - Area feature

-Potential are available for jfm

- 3 Village locations with density-type classes

MT

MISC

Identify areaswhere densityis lt 0.2 within5km from thecenter of the

village

Density map1-dense2-open3-scrub4-blanks

Report

TEAK

BAMBOO

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VillageBuffer 5km

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6

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DATABASE MANAGEMENT AND DATABASE MANAGEMENT AND RETRIEVALRETRIEVAL

HIERARCHICAL MODELINGHIERARCHICAL MODELING

NETWORK MODELINGNETWORK MODELING

RELATIONAL MODELINGRELATIONAL MODELING

ATTRIBUTE QUERRYATTRIBUTE QUERRY

DATABASE: COLLECTION OF INFORMATION ABOUT THINGS AND THEIR RELATIONSHIP TO EACH OTHER

DBMS : A SET OF PROGRAMS THAT IS DESIGNED TO MANIPULATE MAINTAIN DATA IN A DATABSE

UNIVERSITY

DEPARTMENT

STUDENTS PROFESSORS

REGISTRATION COURSES

Hierarchical modeling

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Network linkages

ADVANTAGES OF GIS IN SIMPLE TERMS

• Though collection of data is difficult once it is collected, it can be stored safely in digital form (in computer) forever without damage, which usually happens to our maps.

• Once if a map is prepared accurately it can be printed in any scale without any redrawing.

• Large scale maps at smaller units (Beats) level can be joined for creating maps at divisions or district level, very accurately within few minutes.

• Changes can be incorporated very easily in computer and it doesn’t require any redrawing.

• Same map can be generated even after 100s of years later.• New things can be known after overlay of different themes and a new types of

maps can be generated.• Work can be done faster than manually.• The work of decision makers and end users will become easier.