concepts of remote sensing (rs) and geographic...

Training Programme on Monitoring of Irrigation Projects using Bhuvan Web services

Sunil KUMARDirector, National Water Academy, Pune

June 30th 2014 – NWA, Pune

Concepts ofRemote Sensing (RS) and

Geographic Information System (GIS)

What is Remote Sensing ?

• Remote sensing is the science ofacquiring information about the Earth'ssurface without actually being in contactwith it.

• This is done by sensing and recordingreflected or emitted energy andprocessing, analyzing and applying thatinformation

Remote Sensing-Multidisciplinary

• Optics• Spectroscopy• Photography• Computer• Electronics• Telecommunication• Satellite

Principles of Remote Sensing

A-Energy Source, B-Atmosphere, C-Target , D-Sensor E- Transmission, Reception, and Processing, F-Interpretation and Analysis G-Application

Electromagnetic Radiation

• In 1886, Maxwell found that itmight be possible to combineelectric and magnetic fields,forming self sustainingwaves;

• In 1888 Hertz furtherinvestigated the properties ofElectromagnetic waves.

Wavelength & Frequency

• Wavelength is the length ofone wave cycle, which can bemeasured as the distancebetween successive wavecrest

• Frequency is number of cycleof waves passing a fixed timeper unit of time

The Electromagnetic Spectrum

Interaction with the Atmosphere

Scattering Absorption

Radiation – Target Interactions

A-Absorption; T-Transmission, R-Reflection

Target Interactions-Reflections

Specular Reflection Diffuse Reflection

Sensors

Passive Sensors Active Sensors

What is GIS ?• GIS integrates hardware, software,

and data for capturing, managing,analyzing, and displaying all formsof geographically referencedinformation

• GIS allows to view, understand,question, interpret, and visualizedata in many ways that revealrelationships, patterns, and trends inthe form of maps, globes, reports,and charts.

Component of GIS

GIS – History of Development


• 1854 (John Show) : Cholera Outbreak in London;• Early 20th Century: Photozincography for maps

o Concept of layers;o Originally drown on glass plates;o Later on thin plastic films;o Colour printing introduced;(Layer concept used in modern GIS)


• 1960s: Development of Computer Hardware;o 1960: First operational GIS in Ottawa, Canadao Department of Forestry and Rural Development.o Developed by Dr. Roger Tomlinson (Father of GIS)o Called Canada Geographic Information System

(CGIS)o Used to store, analyze, and manipulate data collected

for the Canada Land Inventoryo Facilitated planning & management.


• 1965-91: Extensive Research at Harvard Graduate School ofDesign led to commercial development

• 1980s: Environmental Systems Research Institute (ESRI),Computer Aided Resource Information System (CARIS),MapInfo, Earth Resource Data Analysis System (ERDAS)emerged as commercial vendors of GIS software.

• 1986: Mapping Display and Analysis System (MIDAS), thefirst desktop GIS product, renamed in 1990 as Mapinfo asMicrosoft windows based package.

GIS – Packages

Open Source GIS software• GRASS GIS – Originally developed by the U.S.

Army Corps of Engineers: a complete GIS.• ILWIS (Integrated Land and Water Information

System) – Integrates image, vector and thematicdata.

• MapWindow GIS – Free desktop application andprogramming component

• uDig – API and source code (Java) available.

GIS – Packages

Commercial GIS software• ArcGIS, ArcView, ArcSDE, ArcIMS, ArcWeb

services and ArcGIS Server by ESRI;• ERDAS, IMAGINE by ERDAS Inc;• MapInfo by Pitney Bowes SoftwareIndigenous GIS Packages• ISROGIS

GIS – Map Features

• Location: Describes position of particular geographic featureon earth surface.

• Attribute: Describes characteristics of geographic featuresuch as type, name, area, length etc.

GIS – Data Model

Vector

Raster

GIS – Data Model

Discrete Space: Lumped models

Continuous Space:Distributed models

Feature/Vector data structures

Raster/griddata structures


Point Feature: Represents asingle point location (eg.location of rain gauge, flow-gauge, manholes)


Line Features: Lines are usedto represent the shape andlocation of geographic objects,too narrow to depict as areas.(eg. Streams, Rivers, Canals)


Polygon Features: Polygon isused to represent a shape, setof connected, orderedcoordinates forming an area(eg. Watersheds, catchments,water bodies tc.)

GIS – Data Model

Point

Line

Polygon

Vector Raster

Zone of cells

GIS – Data Model

Vector Data Format• Point, line, polygon, shape filesRaster Data Format• Jpeg, tiff, gif, DEM

GIS – Map Projections

A map projection is a systematictransformation of the latitudes andlongitudes of locations on thesurface of earth into locations on aplane.Planar representation of actualmap features on the curvedsurface of the earth, all mapprojections necessarily distortsome aspects.


Cylindrical Projections: Meridians are mapped to equallyspaced vertical lines and circles of latitude (parallels) aremapped to horizontal lines. Minimum distortion at equatorialregion & maximum at poles)


Conic Projections: meridians are mapped to equally spacedlines radiating out from the apex and circles of latitude(parallels) are mapped to circular arcs centered on the apex


Azimuthal Projections: Directions from a central point arepreserved and therefore great circles through the central pointare represented by straight lines on the map


Metric Properties of Map:• Area• Shape• Direction• Distance


Preserving direction(Azimuthal), a trait possibleonly from one or two pointsto every other point

Preserving shape locally(conformal ororthomorphic)


Preserving area (equal-areaor equivalent or Authalic)

Preserving distance(equidistant), a traitpossible only between oneor two points and everyother point

GIS Coordinate System

Geographic Coordinate Systems


Universal Transverse Mercator (UTM)


Transverse Mercator Projection

GIS Layers

• GIS allows multiple layers ofinformation to be displayed on a singlemap (eg. Landuse, soil type, Thiessenpolygon).

• One of the main features ofcontemporary GIS

• Layers facilitates representation of realworld.

Overlay Analysis

Superimposing twoor more mapsregistered to acommon coordinatesystem, to showrelationshipsbetween features inthe same study area.

Overlay Analysis

Geodatabase

The geodatabase is the common data storage andmanagement framework which combines "geo" (spatialdata) with "database" (data repository). Geodatabaseassociate data management capabilities to leverage spatialinformation.

Geodatabase

• Fully Relational Data BaseManagement System (RDBMS);

• Facilitates Relationships, Query,Report;

• In-built Attribute dataset, featureclass;

• Provides flexibility to GISenvironment.

GIS Data Collection

• Primary Data: Collected directlyfrom the field. Eg. Remote SensingData (raster), Surveying Data, GPS,LiDAR (vector)

• Secondary Data: Collected fromalready published sources. Eg.Scanned maps, image, aerialphotographs (raster).

GIS Applications

• Environmental assessment• Forestry and wild life tracking• Waste land development• Water resources management• Land use and thematic mapping• Facility management• Urban and town planning• Defence• Land Information Systems• Business and retails

GIS Watershed Analysis

Digital Elevation Model(DEM): is a digital modelor 3D representation of aterrain's surface — createdfrom terrain elevation data.


Fill Sinks: Sinks (andpeaks) are often errors dueto the resolution of thedata or rounding ofelevations to the nearestinteger value.

GIS Watershed Calculations

Fill Sinks: Sinks should be filled to ensure properdelineation of basins and streams. If the sinks are notfilled, a derived drainage network may bediscontinuous.


Flow Direction:Flow direction tool permits todetermine the flow behaviourdepending on the height ofthe adjacent cells of a grid.


Flow Accumulation:Calculates accumulatedflow as the accumulatedweight of all cells flowinginto each downslope cell inthe output raster.


Stream Definition: Thisgenerates a network with themain rivers. It assigns a valueof 1 to the cells that contain aflow accumulation higher than agiven threshold, while null valueare provided to the cells with alower accumulation flow.


Stream Segmentation:It creates a grid of streamsegments, in such a way that allthe cells with the same GridCode compose one differentsegment


Drainage Point Location:This function allows to identifydrainage point at the mostdownstream point in the sub-catchments. This point containsthe largest value in the flowaccumulation grid.


Catchment Grid Delineation:This function creates sub-catchment on the basis ofdrainage pour point &contributing area.

Sunil KUMAR

MANY THANKS

June 30th 2014 – NWA, Pune

concepts of remote sensing (rs) and geographic...

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