MODULE :- 1

INTRODUCTION

TO

RS & GIS (BCV515D)

By

1Dr. Tejaswini N. Bhagwat

Associate Professor

Department of Studies in Civil Engineering

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• Definition : Remote Sensing
• Types of Remote Sensing
• Remote Sensing Process
• Electomagnetic Spectrum
• Black body
• Platform & Sensors

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BASIC CONCEPT of RS

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Humans apply remote sensing in their day-to-day business, through vision, hearing and sense of smell

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WHAT IS REMOTE SENSING ?

SCIENCE and ART of obtaining INFORMATION about an OBJECT, AREA or PHENOMENON through the analysis of data acquired by a DEVICE that is not in contact with the object, area or phenomenon under investigation.

OBJECT – Building, Tankers.

AREA - Water bodies, Forest cover, Cultivated land, Rocky area.

PHENOMENON – Forest Fire, Floods, Oil slick, Earthquake, Drought, Erosion, EIA.

DEVICE – Sensors – Active and Passive.

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DATA AND INFORMATION

• Remote Sensing data provides most accurate spatial information and it can be economically utilized over conventional methods of hydrological surveys.
• Digital enhancement of satellite data results in extraction of maximum information and an increased interpretability.
• In remote sensing, information transfer is accomplished by use of electromagnetic radiation (EMR).
• EMR is considered to span the spectrum of wavelengths from 10-6 µm to 109µm.

Type of Remote Sensing

REMOTE SENSING PROCESS

• ENERGY SOURCE or ILLUMINATION (A)

• RADIATION & THE ATMOSPHERE (B)

• INTERACTION WITH THE TARGET (C)

• RECORDING OF ENERGY BY THE SENSOR (D)

• TRANSMISSIO, RECEPTION AND PROCESSING (E)

• INTERPRETATION AND ANALYSIS (F)

• APPLICATION (G)

REMOTE SENSING IN INDIA

• Central Ministries/ Department:
• Agriculture
• Environment and Forests
• Rural Development
• Urban Development
• Water Resources
• Ocean Development
• Mines
• Science and Technology
• Planning Commission
• Biotechnology
• State Government Agencies
• Private Sector
• NGOs
• Academia/universities

Applications

Users

Service providers > 200

• Agriculture & Crops
• Forest & Bio-resources
• Water Resources
• Geology
• Ocean/coastal
• Environment
• Rural Development
• Urban Management
• Cartography/mapping
• Global Change
• Strategic Applications
• Land and Water Resources Development
• Natural Resources Information System

TELEMEDICINE VIA SATELLITE

Referral �Hospitals

Panel of Doctors

Video Conferencing

Pathology

Cardiology

Video Conferencing

Health Specialist �Centre

Reaching the un-reached

Rural /

Remote/ Inaccessible

Extension education for Doctors in rural/remote areas

POSITIONING AND NAVIGATION

COMMUNICATIONS FOR DEVELOPMENT

MULTI-MEDIA

INFORMATION SERVICES

IRS

INSAT

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INTEGRATED SYSTEM

• VOICE
• VIDEO
• DATA
• TALK-BACK
• 2-WAY VIDEO

PRIORITY AREAS

• WATERSHED DEV.
• HEALTH & EDUCATION
• PANCHAYAT RAJ

TV RECEIVE ONLY TERMINALS

STUDIO/DATA BANK

TALK BACK TERMINAL

• CROP ACREAGE AND PRODUCTION ESTIMATION
• DROUGHT MONITORING AT THE NATIONAL LEVEL
• FLOODED AREA MAPPING ON NEAR REAL TIME BASIS
• WATERSHED PRIORITIZATION
• MARINE FISHERIES DEVELOPMENT
• FORECASTING AGRICULTURAL OUTPUT USING SPACE, AGRO-METEOROLOGY AND LAND-BASED OBSERVATIONS - FASAL

SPACE AND AGRICULTURE

DRINKING WATER

FOR NATION

• Success rate for groundwater targeting raised from 45 % to more than 90%
• 160,000 villages with drinking water problem got benefited

• Prospecting and sustainable development

HYDRO-GEOMORPHOLOGICAL MAP

Scientific source

finding approach

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HYDROGEOMORPHOLOGICAL

MAP

SATELLITE IMAGERY

Locating and Recharging Ground Water

Success rate in locating

water up to 95%

OCEAN APPLICATIONS

IRS P4 - OCM

Sea Surface Temperature �retrieval from NOAA-AVHRR data

POTENTIAL FISHING ZONE

(IRS P-4 OCM DERIVED)

November 17, 1999

0.1

mg/m³

5.0

OFF GOA

OFF �GUJARAT

3.0

November 21, 2000

IRS WiFS based NDVI

May-July 2001

Severely drought

affected districts

DROUGHT MONITORING

KARNATAKA PROVINCE

Increasing NDVI

Targeting social safety nets

Relief and Rehabilitation

Subsidy and Entitlements

Developmental focus

NDVI- normalized difference vegetation index

Reporting hierarchy

May-July 2000

SPACE AND URBAN DEVELOPMENT

• URBAN GROWTH PROFILES
• FACILITY MANAGEMENT
• INFRASTRUCTURE DEVELOPMENT
• CITY/TOWN MAPS
• PROPERTY MANAGEMENT
• MUNICIPAL INFORMATION SYSTEMS
• URBAN INFORMATION SYSTEMS

METEOROLOGICAL APPLICATIONS

DATA COLLECTION SYSTEMS

• Wind Speed
• Temperature
• Humidity
• Etc.

INSAT-3A

Kalpana-1

1. The interpretation of imagery requires a certain skill level

2. Needs cross verification with ground (field) survey data

3. Data from multiple sources may create confusion

4. Objects can be misclassified or confused

5. Distortions may occur in an image due to the relative motion of sensor and source

6. High cost of satellite systems

7. Takes 10 years + to develop, build, test, and launch

LIMITATIONS

Electromagenetic Energy

ELECTROMAGNETIC SPECTRUM

• The Electromagnetic spectrum (EMS) is the distribution of electromagnetic radiation according to energy (or according to frequency or wavelength).
• The electromagnetic spectrum ranges from the shorter wavelengths (including gamma and x-rays) to the longer wavelengths (including microwaves and broadcast radio waves).

Fig. : Electromagnetic spectrum

Fig.: Electromagnetic spectrum:COSMOS

Electromagnetic spectrum - wavelength bands

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Visible range Blue - 0.4 - 0.5 μm

Green - 0.5 – 0.6 μm

Red - 0.6 – 0.7 μm

Infrared (IR): Near IR - 0.7 – 1.3 μm

Mid IR - 1.3 – 3.0 μm

Thermal IR - beyond 3 μm

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Micro wave 1 mm – 1 m

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Earth's atmosphere absorbs energy in γ rays, x rays and ultraviolet bands

– not used in Remote Sensing

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ENERGY INTERACTION WITH THE ATMOSPHERE

• Particles and gases in the atmosphere can affect the incoming light and radiation.
• These effects are caused by the mechanisms of scattering and absorption.

SCATTERING

• Scattering occurs when particles or large gas molecules present in the atmosphere interact with and cause the electromagnetic radiation to be redirected from its original path.

Types of scattering

i) Rayleigh scattering.

ii) Mie scattering.

iii) Non selective scattering

1. Rayleigh scattering occurs when particles are very small compared to the wavelength of the radiation.
1. These could be particles such as small specks of dust or nitrogen and oxygen molecules.
2. Rayleigh scattering causes shorter wavelengths of energy to be scattered much more than longer wavelengths.

ii) Mie scattering occurs when the particles are just about the same size as the wavelength of the radiation.

• Dust, pollen, smoke and water vapour are common causes of Mie scattering which tends to affect longer wavelengths than those affected by Rayleigh scattering.

iii) Non selective scattering the final scattering mechanism of importance is called non selective scattering.

• This occurs when the particles are much larger than the wavelength of the radiation.
• Scattering causes fog and clouds to appear white to our eyes because blue, green, and red light are all scattered in approximately equal quantities

In contrast to the absorption bands, there are areas of the electromagnetic spectrum where the atmosphere is transparent (little or no absorption of radiation) to specific wavelengths. These wavelength bands are known as atmospheric “windows”

Energy interactions with Earth surface features

RESOLUTION

• Resolution is defined as the ability of an entire remote sensing system, including lens antennae, display, exposure, processing, and other factors to render a sharply defined image.

• Small element in a satellite image is a single pixel resolution describes the area on the earth surface represented by a single pixel.

• weather satellite image that has a resolution of 1km each pixel represents the average brightness value over an area that is 1km by 1km

• In higher resolution imagery each pixel represents a much smaller portion of the earth. For example landsat of typically produces imagery with 30m resolution

INDIAN IMAGING CAPABILITY

• EVERY 30 MIN. IMAGING
• 1:1M+ SCALES
• CLIMATE/WEATHER

• VERY 2 DAYS IMAGING
• 1:250K SCALES
• OCEAN APPLICATIONS

• EVERY 5 DAYS IMAGING
• 1:250K SCALES
• NATIONAL SURVEYS

• EVERY 22 DAYS IMAGING
• 1:50K SCALES
• DETAILED RESOURCES SURVEY

• EVERY 5 DAYS IMAGING
• 1:12500 SCALES
• LARGE SCALE MAPPING
• STEREO CAPABILITY

• LOCAL AREA IMAGING
• 1:2000/4000/1:8000 SCALES
• STEREO CAPABILITY
• STEP AND STARE

IMAGE REGISTRATION

• Image registration is the process of transforming the different set of data into one coordinate system; also, may be said as the process of overlaying two or more images of the same scene taken at different times, from different viewpoints or from different sensors

AIRPORT

IMAGE

• Remote sensing images are representations of parts of the earth surface as seen from space.
• The images may be analog or digital. Aerial photographs are examples of analog images while satellite images acquired using electronic sensors are examples of digital images.

IMAGE OF VIDHAN SOUDHA

•  It is important to distinguish between the terms images and photographs in remote sensing.

CHARACTERISTICS OF IMAGES

TECHNIQUES OF INTERPRETATION

Identification of different objects in the scene

(1) Digital interpretation:- Allow for quantitative analysis of all spectral band in imagery simultaneously and is able to detect subtle differences that we cannot.

(2) Visual interpretation: - Does not allow for full exploitation of data provided. A human can only visually interpret three types of remotely sensed information at a time.

ELEMENTS OF VISUAL INTERPRETATION TECHNIQUES

1) Tone refers to the relative brightness or colour of objects in image. Generally, tone is the fundamental element for distinguishing between different targets or features.

2-Shape refers to the general form, structure, or outline of individual objects.

• Shape can be a very distinctive clue for interpretation.
• Straight edge shapes typically represent urban or agricultural (field) targets, while natural features, such as forest edges, are generally more irregular in shape, except where man has created a road or clear cuts.
• Farm or crop land irrigated by rotating sprinkler systems would appear as circular shapes.

3-Size of objects in an image is a function of scale.

• It is important to assess the size of a target relative to other objects in a scene, as well as the absolute size, to aid in the interpretation of that target.

4-Pattern refers to the spatial arrangement of visibly discernible objects.

• Typically an orderly repetition of similar tones and textures will produce a distinctive and ultimately recognizable pattern.
• Orchards with evenly spaced trees and urban streets with regularly spaced houses are good examples of pattern.

5-Texture refers to the arrangement and frequency of tonal variation in particular areas of an image.

• Rough textures would consist of a mottled tone where the grey levels change abruptly in a small area, whereas some of the textures would have very little tonal variation.
• Smooth textures are most often the result of uniform, even surfaces, such as fields, asphalt, or grasslands.

6-Shadow is also helpful in interpretation as it may provide an idea of the profile and relative height of a target or targets which may make identification easier. However, shadows can also reduce or eliminate interpretation in their area of influence, since targets within shadows are much less (or not at all) discernible from their surroundings. Shadow is also useful for enhancing or identifying topography and landforms, particularly in radar imagery.

7-Association takes into account the relationship between other recognizable objects or features in proximity to the target of interest. The identification of features that one would expect to associate with other features may provide information to facilitate identification. In the example given above, commercial properties may be associated with proximity to major transportation routes, whereas residential areas would be associated with schools, playgrounds, and sports fields. In our example, a lake is associated with boats, a marina, and adjacent recreational land.

Fig: Indian Remote Sensing Satellites

Remote Sensing Platform

1.Platform is a stage where sensor or camera is mounted to acquire information about a target under investigation.

2. According to Lillesand and kiefer (2000), a platform is a vehicle, from which a sensor can be operated. For remote sensing applications, sensors should be mounted on suitable stable platforms. These platforms can be ground based, air borne or space borne based.

3. As the platform height increases the observational area increases. Thus, higher the sensor is mounted;large synoptic view is obtained.

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4. The types or characteristics of platform depend on the of sensor to be attached and its application. Depending on task, platform can vary from ladder to satellite.

5. Three types of platforms are used to mount the remote sensors-

1. Ground based Platform
2. Air borne platform and
3. Space borne platform

Ground Based Platform

1.Sensor installed over ground based platforms records detailed information about the feature or surface area such as a crop field or road intersection of limited extent(i.e 200 to 400 sq. m) which may be compared with information collected from aircraft or satellite sensors as per the required of the researcher.

2. Ground observation platforms include-handheld platform, cherry picker, towers, portable masts and vehicles etc.

3. To study properties of single plant or a small patch of grass, ground based platform is used (hand-held or mounted on a tripod).

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4.For the field investigations, some of the most popular platforms have been used are cherry picker platform, portable masts and towers. The cherry picker platforms can be extended to approximately 15m.

5. They have been used by various laboratories to carry spectral reflectance meters and photographic systems.

6. Portable masts are also available in various forms and can be used to support cameras and sensors for testing.

7. Permanent ground platforms like towers and cranes are used for monitoring atmospheric phenomenon and long-term monitoring of terrestrial features.

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8.Towers can be built on site and can be tall enough to project through a forest canopy so that a range of measurements can be taken from the forest floor, through the canopy and from above the canopy.

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2.Air Based Platforms

1. Airborne remote sensing is carried out using specially designed aircrafts or hot air ballons depending on the operational requirements and the availability of budget.
2. Aircraft remote sensing system may also be referred to as sub-orbital or airborne, or aerial remote sensing system. At present, airplanes are the most common airborne platform.
3. Airborne platforms are employed owning to their mobilization flexibility and capability of recording data covering large spatial areas as compared to the ground based sensors.

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4. The speed, altitude as well as orientation of the aircraft must be carefully chosen so as to have minimum influence on the scale, resolution and geometric characteristics of record images.

5. Other airborne observation platforms include ballons, drones (short sky spy) and high altitude sounding rockets. Helicopters are occasionally used.

Balloons

1.Ballons are used for remote sensing observation (aerial photography) and nature conservation studies.Ballon floats at a constant height of about 30km.

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2. It consists of a rigid circular base plate for supporting the entire sensor system which is protected by an insulting and shock proof light casing.

3.The balloon is governed by the wind at the floating altitude. Balloons are rarely used today because they are not very stable and the course of flight is not always predictable, although small balloons carrying expendable probes are still used for some meteorological research.

4.Ballons as platforms are not very expensive like arcrafts. They have a great variety of shapes, sizes and performance capabilities. The balloons have low acceleration, require no power and exhibit low vibrations.

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5.There are three main types of balloon systems, viz.free balloons and powered balloons.

Drones

1. Drone is a miniature remotely piloted aircroft.It is designed to fulfill requirements for a low cost platform, with long endurance, moderate payload capacity and capability to operate without a runway or small runway.
2. Drone includes equipment of photography, infrared detection, radar observation and TV surveillance.
3. It uses satellite communication link.An onboard computer controls the payload and stores data from different sensors and instruments.

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4. Drones was developed on britain during world war-II, is the short sky spy which was originally concieved as a military reconnaissance. Now it plays important role in remote sensing.The unique advantage is that could be accurately located above the area for which data was required and capable to provide both night and day data.

3. Aircraft platforms

1. Aerial platforms are primarily stable wing aircraft. Helicopters are also occasionally used for this purpose. Generally, aircraft are used to collect very detailed image.

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2. Special aircraft with cameras and sensors on vibration less platforms are traditionally used to acquire aerial photographs and images of land surface features.

3. While low altitude aerial photography results in large scale images providing detailed information on the terain, the high smaller scale images offer advantage to cover a larger study area with low spatial resolution.

4. Aircraft platforms offer an economical method of remote sensing data collection for small to large study areas with cameras, electronic imagers, across- tack and along-track scanners, and radar and microwave scanners.

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1.Low altitude aircraft: It is most widely used and generally operates below 30000 ft. They have single engine or light twin engine. It is suitable for obtaining image data for small areas having large scale.

2.Hogh altitude aircraft: Includes jet aircraft with good rate of climb, maximum speed, and high operating ceilling.It acquires imagery for large areas(smaller scale).

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Rockets as Platforms

1.High altitude sounding rocket platforms are useful in assessing the reliability of the remote sensing techmniques as regards their dependence on the distance from the target is concerned.

2.Ballon have a maximum altitude of approxiamately 37km, while satellites cannot orbit below 120km.High altitude sounding rockets can be used to amoderatebaltitude above terrain. Imageries with moderate synoptic view can be obtained from such rockets for area of some 500000 sq.km perframe.

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3.Prior to use of airplanes, aerial photographs were obtained by rocketing a camera into the sky and then retrieving the camera and film.

4. The high altitude sounding rocket is fired from a mobile launcher. During the flight its scanning work is done from a stable altitude, the payload and the spent motor are returned to the ground gently by parachute enabling the recovery of the data.

5. One most important limitations of this system is to ensure that the descending rocket not going to cause damage.

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3. Space Borne Platforms

1. Space borne remote sensing is carried out from the outer space or at an altitude higher than the earth’s atmosphere and utilizes space shuttle or more commonly satellite as platforms.

2. Space borne or satellite platform are onetime cost effected but relatively lower cost per unit area of coverage, can acquire imagery of entire earth without takung permission. Space borne imaging ranges from altitude 250km to 36000km.

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3.Satellites are man made objects that resolve around the earth and sensors installed onboard captures data of earth’s surface covering areas of more than hundreds of sq. km. Because of their orbits, satellites permit repetitive coverage of the earth’s surface on a continuing basis.

4. Ever since the launch of the first earth satellite (i.e Landsat in 1972),satellite based remote sensing has continuously served towards the betterment of science and technology.

There are two types of well recognized satellite platform

1. Manned satellite platforms: Manned satellite platforms are used as the last step,for rigorous testing of the remote sensors on board so that can be finally incorporated in the unmanned satellites. Crew in the manned satellites operates the sensors as per the program schedule.It includes space shuttles ,space crafts, international space stations etc.
2. Unmanned satellite platform:Landsat series,SPOT series and IRS series of remote sensing satellite,NOAA series of meteorological satellites, the entire contelation of the GPS satellites and the GOES and INSAT series of

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geostationary environmental, communication, televison braodcast, weather and earth observation satellite etc are example of unmanned satellite category.

Space borne remote sensing provides the following advantages:

1. Large area coverage:
2. Frequent and repetitive coverage of an area of interest:
3. Quantitative measurement of ground features using radio metrically calibrated sensors;
4. Semi automated computerized processing and analysis;
5. Relatively lower cost unit are of coverage.

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References

• https://www.isro.gov.in/
• https://bhuvanapp1.nrsc.gov.in/bhuvan2d/bhuvan/bhuvan2d.php?toolid=ocean.
• https://earthexplorer.usgs.gov/
• https://qgis.org/download/

THANK YOU