Lecture 1 : Rudiments of Remote Sensing and Advantages

Summary

This course, 'Remote Sensing Essentials' by Arun Saraf from IIT Roorkee, introduces the fundamentals of remote sensing, covering its definition, advantages, and applications. The 30-hour course explores the technology of acquiring Earth's surface information without direct contact, using various platforms like satellites and UAVs. It delves into the process of sensing, recording, and analyzing reflected or emitted energy from the Earth's surface for diverse applications, emphasizing the benefits of remote sensing in providing a synoptic view, repeatability, multispectral capabilities, and its wide-ranging uses in fields from agriculture to disaster management.

Takeaways

• 📚 The course 'Remote Sensing Essentials' is a 30-hour program covering the basics, advantages, and applications of remote sensing technology.
• 🔬 Remote sensing is defined as the technology of acquiring information about the Earth's surface without physical contact, using sensors that can detect a wide range of the electromagnetic spectrum.
• 👀 Human eyes and animals have natural remote sensing capabilities, but humans have developed sensors that can operate beyond the visible spectrum, including infrared, thermal, and microwave regions.
• 🛰️ Remote sensing is performed using various platforms, including ground-based, aerial, spacecraft, and extraterrestrial satellites, each with different capabilities and coverage areas.
• 🌐 The process of remote sensing involves the interaction between incident radiation and targets of interest, recorded by sensors and transmitted back to Earth for processing and analysis.
• 🌟 The energy source for remote sensing is typically the sun, but any object above absolute zero can emit energy that can be detected by sensors.
• 🌍 The atmosphere plays a crucial role in remote sensing, as it can introduce distortions and errors in the energy that is reflected or emitted from the Earth's surface back to the sensors.
• 📈 Remote sensing data requires processing, including corrections and analysis, to be useful for various applications such as weather forecasting, disaster management, and resource monitoring.
• 🚀 The script discusses different types of remote sensing platforms, including the evolution from balloons to aircraft, satellites, and unmanned aerial vehicles (UAVs), each offering different advantages.
• 🌐 The advantages of remote sensing include synoptic view, global coverage, repeatability, multispectral capabilities, multi-resolution images, near real-time data, systematic data collection, and accessibility to otherwise inaccessible areas.
• 🌐 The script highlights the versatility of remote sensing applications, ranging from agriculture to natural disaster management, and its importance in modern technology and research.

Q & A

What is the main topic of the course discussed in the script?

The main topic of the course is 'Remote Sensing Essentials,' which covers the basics, advantages, and various applications of remote sensing.

What is the formal definition of remote sensing mentioned in the script?

Remote sensing is defined as the technology of acquiring information about the Earth's surface without actually being in contact with it.

What are the different types of platforms used in remote sensing according to the script?

The platforms mentioned include ground-based, aerial (aircrafts, helicopters), spacecraft (satellites), and extraterrestrial remote sensing like moon or Mars satellites.

What is the significance of the electromagnetic (EMF) spectrum in remote sensing?

The EMF spectrum is significant because it is the range within which sensors operate to detect and measure the energy reflected or emitted by the Earth's surface.

How does the script describe the process of remote sensing?

The process involves sensing and recording the reflection or emitted energy from the Earth's surface, processing and analyzing this data, and then using the images for various applications.

What is the role of image processing in remote sensing as discussed in the script?

Image processing is crucial as it involves correcting raw data or images, performing various corrections, and interpreting the images for different applications.

What are the components of the remote sensing process mentioned in the script?

The components include the energy source (illumination), the interaction with the target (Earth's surface), recording of energy by the sensor, transmission of data, and processing, analysis, and application of the data.

What is the importance of multispectral sensors in remote sensing?

Multispectral sensors are important as they allow for the measurement of energy at different parts of the EMF spectrum, providing a more comprehensive view of the Earth's surface beyond the range of human vision.

How does the script explain the advantages of using remote sensing for inaccessible areas?

Remote sensing is advantageous for inaccessible areas because satellites can acquire data from areas that are not easily reachable by humans, which is particularly useful in natural disasters and other emergency situations.

What are some of the practical applications of remote sensing mentioned in the script?

Some practical applications include weather forecasting, natural disaster management, resource management, agriculture, geological mapping, and climate change studies.

How does the script describe the evolution of remote sensing platforms?

The script describes the evolution from initial use of balloons to aircrafts, helicopters, satellites, and now unmanned aerial vehicles (UAVs), each offering different capabilities and advantages.

Outlines

00:00

📚 Introduction to Remote Sensing Essentials

Arun Saraf from IIT Roorkee introduces the course on remote sensing essentials, covering the basics, advantages, and applications of remote sensing. The course spans 30 hours and begins with the rudiments of remote sensing, including its formal definition as the technology for acquiring information about the Earth's surface without physical contact. Various platforms for remote sensing, such as satellites and sensors, are mentioned, highlighting their roles in detecting different parts of the electromagnetic spectrum and their development for ground, aerial, and space-based applications. The lecture also touches on the recording and processing of reflected or emitted energy from the Earth's surface for various uses.

05:01

🌐 Components and Platforms of Remote Sensing

The script delves into the components of remote sensing, starting with the energy source or illumination, which is essential for capturing reflected energy from the Earth. It discusses the role of the atmosphere in remote sensing, the interaction of radiation with the Earth's surface, and the recording of this energy by sensors on satellites or other platforms. The paragraph also covers different types of remote sensing platforms, including their evolution from balloons to aircraft and satellites, with a focus on polar orbiting satellites that provide extensive data for analysis. The potential for real-time data transmission and the use of satellite Earth stations for data reception and processing are also highlighted.

10:01

🛰️ Remote Sensing Platforms and Sensor Technology

This paragraph discusses the evolution and variety of remote sensing platforms, ranging from space shuttles to unmanned aerial vehicles (UAVs), each with specific capabilities and altitudes. It emphasizes the popularity of UAVs for high-resolution, real-time imaging in applications like disaster management and agriculture. The text also explains the role of different types of satellites, including polar orbiting and geostationary satellites, in acquiring remote sensing data. The importance of the seven elements involved in imaging systems or sensors is outlined, from the satellite or vehicle to the Earth's surface and the energy source, atmosphere, and sensor recording system.

15:03

🔬 The Role of Atmosphere and Sensor Recording in Remote Sensing

The script explains how the atmosphere influences remote sensing by interacting with the energy traveling from the source to the target and back to the sensor. It discusses the importance of minimizing atmospheric errors for more useful and accurate images. The paragraph also describes the interaction of energy with the Earth's surface, depending on the properties of the target and the radiation, and how this interaction results in different behaviors of the reflected or emitted energy. The role of sensors in recording this energy and the subsequent transmission of data to Earth stations for processing and analysis is emphasized.

20:04

🖼️ Image Processing and Interpretation in Remote Sensing

The paragraph focuses on the post-acquisition processes in remote sensing, including the reception of data at processing stations, digital output generation, and the interpretation and analysis of images by experts for various applications. It highlights the versatility of remote sensing technology, which can be applied across different domains such as civil engineering, geology, and environmental science. The use of software tools, neural networks, and fuzzy logic for digital image interpretation is mentioned, as well as the extraction of information from images for problem-solving and new insights.

25:04

🌏 Advantages and Applications of Remote Sensing

This section of the script enumerates the advantages of remote sensing, such as the synoptic view it provides, allowing for large area coverage with a single image. It discusses the trade-off between spatial resolution and the width of the image swath, the global coverage possible with polar orbiting satellites, and the repeatability of satellite imaging. The paragraph also covers the benefits of multispectral sensors, multi-resolution imaging, near real-time data acquisition, systematic data collection for time series analysis, and the use of remote sensing in inaccessible areas. The generic nature of remote sensing data for multiple applications is also highlighted.

30:09

🔍 Further Advantages of Remote Sensing Technology

The script continues to elaborate on the advantages of remote sensing, including its use in processing digital data, the ability of microwave sensors to penetrate clouds and dry sand, and the optimization of field investigations. It mentions the cost-effectiveness of updating and revising existing maps using high-resolution satellite images and the creation of color composites for detailed area analysis. The role of remote sensing in natural disaster studies and rescue missions is emphasized, along with its use in climate change research, providing fundamental biophysical information and data for modeling.

35:14

🌱 Conclusion on the Essentials of Remote Sensing

The final paragraph concludes the discussion on remote sensing essentials, summarizing the key points covered in the script. It reiterates the passive and non-invasive nature of remote sensing, its systematic data collection, and its ability to provide fundamental information under controlled conditions. The paragraph also emphasizes the importance of remote sensing in climate change studies, its cost-effectiveness due to technological improvements, and its wide-ranging applications from agriculture to space exploration.

Keywords

💡Remote Sensing

Remote sensing is the technology of acquiring information about the Earth's surface without physical contact. It is central to the video's theme, as it encompasses the various methods and technologies used to gather data from a distance. The script discusses the formal definition, the technology's capabilities, and its applications in diverse fields.

💡Electromagnetic Spectrum

The electromagnetic spectrum refers to the range of frequencies (wavelengths) of electromagnetic radiation. In the context of remote sensing, it is crucial because different parts of the spectrum are used to detect and analyze various features of the Earth's surface. The script mentions that human eyes are sensitive to only a limited part of this spectrum, while sensors can be designed to work across a broader range, including infrared and microwave regions.

💡Satellites

Satellites are artificial objects that orbit the Earth and are used for various purposes, including remote sensing. The script discusses different types of satellites, such as polar orbiting and geostationary satellites, and their roles in capturing images and data about the Earth's surface from space.

💡Unmanned Aerial Vehicles (UAVs)

UAVs, or drones, are aircraft without a human pilot aboard, which can be used for remote sensing. They are highlighted in the script as a modern platform for capturing high-resolution images and are particularly useful for real-time monitoring and areas that are difficult to access.

💡Spatial Resolution

Spatial resolution in remote sensing refers to the level of detail visible in an image, typically measured in ground sample distance (GSD). The script explains how different sensors have varying spatial resolutions, affecting the size of the area they can cover in a single image and the level of detail they can provide.

💡Multispectral Sensing

Multispectral sensing is the process of capturing images in multiple spectral bands, allowing for the detection of features not visible to the human eye. The script mentions multispectral sensors as an advantage of remote sensing technology, enabling the capture of data beyond the visible light spectrum.

💡Atmosphere

The atmosphere plays a significant role in remote sensing as it interacts with the electromagnetic radiation traveling from the source to the Earth and back to the sensor. The script discusses how the atmosphere can introduce errors and distortions in the data, which must be corrected during image processing.

💡Image Processing

Image processing involves the manipulation and analysis of images to extract useful information. The script touches on the necessity of image processing in remote sensing, where raw data is corrected and analyzed to produce meaningful and usable images for various applications.

💡Synoptic View

A synoptic view provides a comprehensive perspective of a large area, which is one of the advantages of remote sensing mentioned in the script. It allows for the simultaneous observation of vast landscapes, useful for monitoring and analyzing geographical features and patterns.

💡Time Series Analysis

Time series analysis is the study of data points collected or recorded at successive, equally spaced points in time. The script mentions the ability of remote sensing to provide systematic data collection, enabling time series analysis to observe changes over time in various environmental and geographical features.

💡Applications

The script discusses various applications of remote sensing, such as weather forecasting, natural disaster management, and resource monitoring. It emphasizes the versatility and importance of remote sensing data across different domains and industries.

Highlights

Remote sensing is defined as the technology of acquiring information about the Earth's surface without physical contact.

The course 'Remote Sensing Essentials' will cover the basics, advantages, and various applications of remote sensing over 30 hours.

Remote sensing uses a wide range of the electromagnetic spectrum, including visible, infrared, and microwave regions.

Sensors have been developed for ground, aerial, spacecraft, and extraterrestrial remote sensing applications.

Remote sensing involves recording the reflection or emitted energy from the Earth's surface, which is then processed and analyzed.

The process of remote sensing includes elements such as the energy source, interaction with the Earth's surface, and data transmission.

Different platforms for remote sensing include satellites, aircraft, balloons, and unmanned aerial vehicles (UAVs).

Polar orbiting satellites are primarily used for remote sensing, offering coverage around 840 km above the Earth.

Remote sensing platforms have evolved from balloons to UAVs, providing various heights and resolutions for data acquisition.

The atmosphere plays a crucial role in remote sensing, affecting the energy's interaction with the Earth's surface and its reflection back to sensors.

Remote sensing technology allows for systematic data collection and time series analysis due to the repeatability of satellite orbits.

Remote sensing images are used in various applications, from agriculture to disaster management, due to their multispectral and multi-resolution capabilities.

The advantages of remote sensing include synoptic view, global coverage, repeatability, multispectral sensing, and multi-resolution imaging.

Remote sensing data is digital, allowing for automated or semi-automated processing and analysis.

Microwave remote sensing can penetrate clouds and dry sand, providing data in conditions where optical or thermal sensing may fail.

Remote sensing optimizes field investigations by allowing for preliminary exploration and planning using high-resolution images.

Updating or revising existing maps with remote sensing data is more cost-effective and faster than traditional field surveys.

Remote sensing provides color composites that enhance the identification of features such as water bodies, forests, and geological structures.

Remote sensing is extensively used in natural disaster studies and rescue missions, providing crucial data for response planning.

Overall, remote sensing is cost-effective, unobtrusive, and provides systematic data collection for various scientific and practical applications.

Transcripts

Hello everyone, and I am Arun Saraf from IIT Roorkee.

And we will be discussing in this course essentials of remote sensing which I have given name

is remote sensing essentials.

Basically we will be looking in this course about the basics that is rudiments of remote

sensing advantages and also various applications which we will be ahh discussing in due course

of time.

So, this is 30 hours ahh course, which we are going to have.

So in this series of lectures and I am going for first one, that is rudiments of remote

sensing and advantages.

So, very briefly in this lecture we will be going to discuss what exactly remote sensing

and especially the formal formal definition of remote sensing as well.

And then and different platforms and other things.

And we will be also discussing.

So let us start first with the word basically remote sensing, in the books or literature,

this is how it is defined.

That is remote sensing is the technology of acquiring information about the Earth's surface

without actually being in contact with it.

And that that means if I say in simple words, that anything which we can sense film, our

eyes or cameras or sensors, without basically coming into physical contact of it, and then

we can say as a ahh this that we are doing remote sensing.

As you know that our eyes are very sensitive.

And though they work in the very limited part of EMF spectrum, which we will be discussing

in detail that is only visible part of the spectrum, but it is a very efficient ahh remote

sensor or a similarly, there are some ahh other you know animals are also having different

kind of or similar or different kind of capabilities of sensing things.

And because human has designed sensors, which can not only work with the invisible part

of EMF spectrum.

But they can work in the infrared thermal infrared, even in microwave regions and not

only active microwave, but in passive microwave also.

So, a large part of EMF spectrum wherever atmosphere windows are available instruments

are sensors have been developed, some are ground ways, some are aerial based, and many,

many of them are a spacecraft based on based on satellites.

And also you know that now we are going for extraterrestrial ahh remote sensing like going

on moon putting satellites around the moon or Mars and so on.

So, all these things will be also discussing in brief in this course, ahh this is the remote

sensing as you know is done by sensing and recording.

And that is a recording what recording that is the reflection or emitted energy, which

is coming out of the surface of the Earth.

And then we process it and analyze it and up and then use this data, these images for

different applications.

But as I gave the example of human eyes, we do not have that that kind of recording facilities

only it goes in memories, but we cannot replay, ahh but using instruments or sensors it is

possible to require record the reflection or emitted energy of the surface of the Earth.

And it is also possible to acquire that information or that data which has been sense by satellite,

which is based ahh which is in orbiting around the Earth or moon.

And to Earth ahh by through satellite Earth stations.

So, in this course also very briefly we will be also touching that aspect that how data

is acquired from satellites and then they send the signals and so on.

And then of course, whatever the data or images which we get generally are in raw form.

So, we need to do the image processing a lot of corrections are also performed.

And we also analyze interpret the images and then use for different application.

So, this is what is basically ahh remote sensing in this one.

if we if we see different parts of remote sensing or different components of remote

sensing, so, we will go a step by step that the the E which is which you see here is the

energy source or illumination, this is very much required that is essential especially

for the reflected energy which we have just discussed in the definition of remote sensing

that you need either illumination source or illumination or reflection that is possible

in daytime or you need to imitate emittance that is any object which is above absolute

0 will also emit energy.

That energy can be also detected by satellite.

So, this is what it is is shown here, that E is the illumination source, B is the radiation

and the atmosphere, so that the energy which is coming from ahh sun reaches towards the

Earth, which is a C here and then some of this energy is reflected or emitted and then

it reaches to the satellites and another D is also shown, because this is shown for the

microwave and satellites.

In our sensors that the satellite itself they send the microwave signals towards the Earth

and then whatever the work is capturing ahh or the energy which goes back again is recorded

by the satellite.

So, that is why here B is also shown.

So, then the C part is the interaction with the target or the surface of the Earth in

case of passive remote sensing and recording of energy by the sensor.

Whatever the signals which reaches or energy which reaches to the sensor, it is recorded

by the satellites which are orbiting and the Earth, moon or Mars and then the transmitter

this in ahh these signals, whatever the data which they have acquired or satellite images

they transferred towards the Earth.

So, this is the satellite Earth station and so these the receiving is done some ahh first

level or second level of processing is also done.

And then it is recorded here and then of course, it goes for processing analysis and interpretation.

So, that part comes the ahh the G that is the application also.

It is also possible that a the satellite which is which has recorded a scene or an image

can also transmit to some other satellite which might be orbiting over ahh a satellite

particular satellite Earth station.

So, almost in a real time that data though the satellite might be safe flying over ahh

over India.

But ahh the Earth station might be new is so through a satellite that transmission goes

from one satellite to another and then and that signal goes to ahh that station where

it is located.

So, all kinds of ahh possibilities are there for data recording as well as all kinds of

possibilities are there for sensing ahh these signals either illuminated or emitted.

So, this is all what we are having in remote sensing.

Now, there are different types of platforms which are discussed in remote sensing which

are considered as part of remote sensing.

And this is a ahh changing at a quite fast rate I would say that because initially we

started remote sensing with ahh balloons, so, some cameras were put on balloons, and

though in this diagram is not soon because I am discussing here only the present day

remote sensing platforms, and then later on then it came on the aircraft but this these

aircrafts are having their own limitations, helicopters are also their aircrafts are there.

So they can fly up to 1.3, 1.5 or maybe 10 kilometer ahh in the in the air or in the

atmosphere.

But the more robotic platforms are the satellites which are very far around the 700 to 900 kilometer,

these these satellites I am talking about the remote sensing satellites roughly they

are somewhere 840 50 kilometer + - 10 kilometer, these remote sensing polar orbiting or near

polar satellites, these are the satellite which I am talking here.

Though there are different types of orbits are also they are in in due course and time

we will be might be also discussing some basic types of orbits which are used in a space

or in satellite remote sensing.

But the the remote sensing which we discuss or I am going to discuss mainly will focus

on the data or images which are acquired by these polar orbiting satellites, which are

around 840 or 50 kilometer in space.

It is also possible to acquire data it has been done on the past using space shuttles,

like one of the examples of through space shuttles or missions are there ahh like a

shuttle radar topography mission, which was done using the space shuttle.

So, that is also possible, they fly somewhere between 185 to ahh 576 kilometer above the

Earth and then there are also possibility of airborne SAR, airborne aircraft are also

shown here.

But air bornes are ahh they fly much higher above the ground and the latest the new edition

in remote sensing platforms is a this is what is UAB and unmanned aerial vehicles which

are becoming very popular for ahh for different kinds of photography or imaging, and all kinds

of payloads can be put depending on the capability of these drones.

And though they cannot fly very high, they cannot cover a very large area.

But if somebody is looking for a very high resolution images and almost in real time

and they would like to have the full control over it, then you will be can be one of the

options and this is being used in case of disasters in agriculture and a lot of resources

management also, currently you UAVs are being used, very popular in, very cost effective

also sometimes.

So, the different platforms are there at different heights to cover the various parts of the

Earth.

And as you know that then there are 100 of satellites orbiting and and different depth

in the space.

And there are the satellites which before we will be focusing as I have already mentioned,

near polar orbiting satellites which are shown in these ahh red color orbits, there are satellites

which are ahh as jewel geostationary satellites, which are shown here like INSAT series of

India.

These are the geostationary satellites.

We are also having like these polar orbiting satellites, like IRS satellite, landsat and

meteosat and NOAAVHR, NOAA satellite, there are many such satellite which are orbiting

in polar orbits.

And there are some other different types of orbits are they ahh, so very not all satellites

are shown but many, many such satellites are shown ahh which which have which have been

put by different countries in different orbits for completely, sometimes different purposes.

But most of the time, we are going to discuss about the polar orbiting or near near polar

orbiting and sun synchronous satellites, which are around 850 kilometer away from us.

So as you as we have just discussed that remote sensing is the process which involves an interaction

between incident radiation and the targets of interest.

And this is exemplified by the use of imaging systems or sensors where the ahh these following

7 elements are involved.

What are those 7 elements as we start with the satellite.

So, there is a very important component of satellite based remote sensing, if it is drone,

then drone is the some vehicle is required on which a payload can be put.

So, that is what is required.

So, instead of satellite we can say vehicle then of course the there is a Earth and different

objects on the Earth whether the water body is there, forest is there, grass is there,

bare soil and so and so forth.

Of course, you need a energy source.

So, we are having sun here illumination source.

And then in between you are having atmosphere in between means, the between sun and Earth

and between satellite and Earth and this atmosphere plays a very important role in in field of

remote sensing.

And because ahh though the solar energy is coming through the atmosphere, so, the entire

energy is not reaching towards the Earth.

And the same way when it is reflected back and say to the satellite, then again entire

reflection or emission is not reaching towards the Earth because in between there is atmosphere

and this atmosphere while ahh the energy or signals which are going back ahh through the

atmosphere there are a lot of distortions are created, and errors are introduced and

we try to minimize by through our processing or techniques which are available currently.

We try to minimize these atmospheric errors as well.

So that our images becomes much more useful quantitatively and qualitatively as well.

So, the 7 components are here, ahh which are key elements in remote sensing also ahh one

by one we will be discussing these elements ahh like a first as A is here shown also that

energy source illumination, that is the first requirement for remote sensing is to have

an energy source and which illustrates or provide electromagnetic energy to the target

of interest.

And that the second element or second important component of remote sensing is the radiation

and atmosphere.

Of course, atmosphere is there, but if we talk about remote sensing of Mars or moon,

then in those ahh extraterrestrial bodies like Mars, Mars has a very thin atmosphere.

And therefore, the distortions or errors or you know the blurriness which might come in

case of Earth images, that is not very common in case of Mars.

So, that atmosphere there is thin and has got less role to play as compared to the Earth.

But, when we are on the Earth or we are talking about satellite images or remote sensing of

the Earth, then atmosphere plays a very important role as as we know that when the energy travels

from its source to the target, it will come in contact with ahh atmosphere and interact

with it ahh and it passes through also some part of energy and this interaction ahh may

take place a second time as the energy travels from the target to the sensor.

By second time is I have already said that when it is coming from Sun to the Earth, it

has to travel through atmosphere, which is in between, and when it goes back after illuminating

the surface or image and energy, then again it has to pass through the atmosphere that

is ahh that is why it is second time.

So, second time is more important in case of remote sensing of the Earth.

Then comes the C part that is the interaction with the target or interaction with the surface

of the Earth.

So, once that energy ahh reaches ahh its way through the atmosphere to the target through

illumination source like sun and then it interacts with the target depending on the properties

of both the target and the radiation.

Here the properties means that target might be a water body might be ocean, or a land

or a desert, or a dense forest, or a building or a similar objects or a mountain or a snow

peaks or glaciers.

So, different objects which are present on the surface of the Earth will interact differently

with the signals which are coming ahh or the energy which is coming to the sun and then

they will behave differently the radiation is will be going to be different and then

whatever is reflected back or reaches to the satellite, that is what it is recorded ahh

by the sensor which are on board of the satellites, that is the D ahh component.

And after the energy has been scattered or emitted ahh from the target in between with

the of course, it has gone through also and absorption or scattering within the atmosphere

as well.

And so, we require a sensor that maybe a remote sensor and maybe own board of satellite or

aircraft or helicopter to collect and record the electromagnetic radiation which has reflected

or scattered back from the Earth.

So, you record a recording system also with that sensor and this transmission and then

of course, then whatever is recording is done either it should be transmitted live that

is by direct broadcasting or recording in direct broadcasting, all kinds of options

are available with different types of sensors.

So, transmission is also important component or remote sensing and these whatever the data

it has collected, whatever the image is has collected, it has to transmit towards the

satellite Earth station like soon shown here.

Then these restrictions received the data.

So, the reception part and then of course processing first level processing, second

and then ahh satellite analysis, image analysis interpretations and of course applications.

So, the energy recorded by the sensor has to be transmitted, of in in form of electronic

form and basically be receiving digital form.

So, all the remote sensing images recorded in digital form not analog form nowadays.

And then processing stations or satellite this systems receives this these data sets

or images and then processing will take place and generally the outputs nowadays is very

common is the digital one, but hard copies can also be prepared.

And then of course, after all this then we come to the interpretation and analysis part

ahh that is here and that is mainly in the lab work also.

So, the processed image is interpreted by experts or for application scientists for

different purposes.

If one is civil engineer, then he might be using that image for civil engineering purposes.

If somebody is geologists then he would be using for identification of some mineral deposits

or ahh coal or oil or gas or whatever.

And similarly for a scientists will be looking at different density of for us maybe different

species of plants and so on.

So the interpreting and the same image can be interpreted for different purposes.

That is why also it is said that the remote sensing is a generic technology that means

it can be applied in various applications of various domains.

And then interpretation can be visually interpretations can be ahh digitally based on the softwares

or maybe more recent tools like neural network and basically classification based on fuzzy

logic and other things.

And then ahh ultimate purpose is to extract information of the Earth objects from these

images for different applications.

So that is the main purpose.

And then finally comes the applications that the final element remote sensing process is

achieved when we apply the information, we have been able to extract from imagery about

the target in order to better understand it reveal some few new information or assist

in solving a particular problem.

You know that nowadays remote sensing images, though it is need not to be everyone is expert

on remote sensing.

But, from in day to day life we have started using remote sensing.

For example, when we see the weather forecast is so whoever in the television or on net

when it is displayed the satellite image is also displayed and clouds and if there are

some cyclones are developing or other thing, they are also ahh shown through these images.

So we start seeing images for different, so it can be also used for weather forecasting

or natural disaster management and various other applications.

So, these satellite images are becoming very common Google Earth is another ahh product,

which provides lot of images.

And you can zoom it and as soon as you zoom it, you get higher and higher spatial resolution

images of any location of the world.

So, because thousands and millions of images have been put in that Google Earth database,

which can be accessed by very easily by the users of their ahh area of interest.

Now, what are the advantages, some you might have realized by seeing or while going through

this discussion is the synoptic view that is the biggest advantage but because generally

remote sensing is done from a distance.

So when you go from from an object away from object to the distance, you start covering

a large area and so in one go you can cover a very large area of course, it depends on

the spatial resolution of the sensor.

But nonetheless, ahh it will provide a synoptic view.

So, a large area can be covered in one go that is what meaning here is.

So, suppose if I take example of NOAA AVHRR, NOAA is the name of satellite AVHRR is the

advanced very high ahh resolution radiometer and that having a spatial resolution about

1.1 kilometer and that covers about 2800 kilometer wide swath.

So, in one image in one go you can cover a 2800 kilometer ahh swath or a strip of the

part of the Earth.

So, it provides a very large coverage, but as you go higher and higher spatial resolution,

the size of this swath, the breadth of the swath reduces and if I take example of one

meter resolutions say ikonos images, then the swath reduces to 11 kilometer.

So, from 1 clue 1.1 kilometer spatial resolution and 28 2800 kilometer swath you reduce to

11 kilometers swath, but the spatial resolution you are getting all 1 meter.

So, as you go for higher spatial resolution, the breadth of the swath reduces, but it is

still that higher spatial resolution image will provide a synoptic view.

So that is the one of the biggest advantages and the remote sensing in day to day nowadays,

we are seeing these drones have become very common and whether it is a marriage or some

function or some large programs there ahh these videographers have started to have using

these ahh drones.

And why they use to cover a large area.

So they provide also the synoptic view, global coverage.

When you are going for satellite based remote sensing, not drone based of course, then satellite

based remote sensing, then you can cover the entire globe is basically I am talking about

a polar orbiting satellite like IRS LANSAT port or many, many such satellites.

So, they provide a completely global coverage sometimes except for ahh polar regions, but

otherwise they provide a complete global coverage.

Repeatability that is another best advantages with satellite based remote sensing, that

each satellite will be coming or revisiting the same part of the Earth, maybe after a

few hours like in case of new NOAA VHRR or maybe after 30 days, 16 days, 18 days depending

on the resolution and depending on the distance from the Earth.

So, these repeatability is another best advantage of remote sensing satellite based remote sensing.

So you can have coverage like that, and then you are having multispectral sensors, that

is another very good advantage because in the beginning I mentioned that our eye work

only in the visible part of EMF spectrum.

But if we if I want to scan a part of the earth, using infrared or thermal infrared

and of course visible as well, then I can have different you know, bands or channels,

then we call it the multispectral.

So, these sensors can be designed and been designed, they are already there are lot of

different types of sensors are there, which can sense or measure the energy at different

parts of EMF spectrum, beyond the range of as mentioned, human vision.

Multi resolution images are now possible.

Within even 1 satellite different sensors are installed.

Like I give the example of IRS so earlier in IRSV IRS-1Z 1D satellites.

We had ahh 3 types of sensor, we have panchromatic sensors, which was giving black and white

images.

Then we have multispectral sensors sensors like LISS 2, LISS 3, LISS 4 and so on, so

forth.

So, within one platform you can have different payloads and multi resolution images can also

be acquired, it is it is a very common thing nowadays with satellite based remote sensing,

it is also possible to have images data in near real time.

Once the satellite has acquired and there are satellites which can directly transmit

towards the Earth.

So, if you are having your own satellite Earth station in real time you can acquire the data,

though the satellite is scanning of the sensor is just scanning that part of the Earth.

If it is in range of your ahh satellite Earth station or antenna, then in real time you

can get the images and then systematic data collection because the repeatability is fixed

and the the coverage is fixed.

So, you get a complete ahh sequence of data.

So, the time series analysis is become very possible very much possible with the satellite

based remote sensing.

So, since the data collection is very systematic, it is not common the drone or any such or

aerial or airborne remote sensing but mainly with satellite based remote sensing.

The only solution sometimes for otherwise inaccessible areas.

This is another important point, because there are many power there are many parts in the

world which are inaccessible to human, not easily reachable, but the satellites can reach

that means they can acquire the data and provide to ahh whoever needs for that time and especially

in case of natural disasters, and satellite remote sensing plays a very important role.

And finally, the generic data which I have already mentioned that one data set one image

can be used by 10 or 20 types of applications.

So, there are multi purposes are associated with a single remote sensing data sets and

that is another very big advantage like the first one the synoptic view, the last one

the generic data and in between all are a big advantages with remote sensing and that

is why remote sensing is being used from agriculture to natural disaster from civil engineering

to ahh our sciences or in a on the Earth or moon on Mars or explore the ahh universe.

So, for all kinds of such missions remote sensing techniques are being used.

Another few more advantages of remote sensing and which is when we go at the processing

level because data being acquired by these satellites, which is in digital form and therefore

lot of processing either can be done in automatic manner or semi automatic manner.

So, analysis and processing becomes very fun because originally generically the data in

digital form.

If we are working in microwave region, then microwave advantage with microwaves that it

can penetrate through the clouds.

Because the the waves or bender which we are covering in microwave, the waves are having

a larger and you know larger ahh wave length and therefore, they can penetrate the clouds

and also sometimes in dry sand and then it can be used.

This microbial remote sensing has been used in India ahh to identify or locate the old

lost courses of social theory in Rajasthan desert because the dry sand was there.

So, as soon as the moisture comes that can be imaged or mapped by these microwave sensors.

And of course in a natural disaster conditions especially in flooding, and sometimes there

are clouds or enduring flooding most of the time there are clouds.

So, if we imply the remote microwave remote sensing, then these can penetrate the optical

remote sensing may not work the thermal may not work in flood and may not work, but microwave

remote sensing can work in such conditions.

It also optimizes field investigations it it will note, it can never replace the field

investigations, the field work or field investigates, site investigation have to be there a ground

routing have to be there, but one can plan very well using remote sensing, one can optimize

and one can take field investigation at a very fast rate by implying the remote sensing

technology as it is happening in geological map or mineral exploration or in civil engineering.

First people nowadays starts exploding or seeing things on Google Earth, then the plan

many many field investigation side investigations just based on Google Earth data, which are

the high resolution images, and then they go to that specific point which need to be

checked on the ground.

And therefore, it optimizes field investigations, updating or revision of existing maps is expensive

and faster.

So, it is inexpensive that whenever there are old maps are there if you want to upgrade

and then you imply the high resolution satellite images, and then these can be upgraded like

survey of India, have you started doing this thing that they are now using in order to

update the topographic maps they are using now satellite images to upgrade and that process

become because if everything has to be checked in the field and it is upgraded.

Then it is very expensive, but employing remote sensing data becomes inexpensive inexpensive

and faster and color composites because we are talking about multispectral remote sensing.

So, therefore color composites can be created and they ensures the details of the area that

we can I can identify very easily the water bodies, I can identify the turbidity in water,

in pollution in water or forest I can identify density of forest.

I can identify different species of forests or if I talk in case of our sciences or in

geology, then I can to some extent I can identify different types of rocks and geological structures

if they are of larger scale.

And then and there are advantages with remote sensing is in natural disasters studies and

rescue missions.

And then based remote sensing based rescue missions can become easier and fast and this

is has become a this has become a normal practice.

And extensively it is being used when in 2015 Nepal earthquake occurred and people or different

countries shared their whatever the satellite data, current satellite data they had, which

was covering and and the area which got affected by those series of earthquakes.

And these rescue missions, ahh use the data and could prepare a lot of plans and maps

and then these operations were done like that.

And of course, so overall it is cost effective.

And because they are doing things in the field getting updating information in the field

is very expensive.

And where is using remote sensing data, it becomes very much possible earlier when remote

sensing is starting the real remote sensing like lens at one in 1972 at that time, the

satellite life of the satellite used to be say 3 years, 4 years like that.

But nowadays, the the technology has improved, electronics has improved, the solar panels

have improved, the batteries have improved.

And now a satellite when it is known sometimes they are lasting for more than 10 years.

So, they are becoming further cost effective.

So, these are the various advantages of remote sensing which can be ahh used implied and

lot of work can be done implying remote sensing data.

Now, there are some other little bit more discussion on this advantages that remote

sensing is on obviously, on unobtrusive that is it is a passive thing.

It does not destroy anything.

So it records the reflected or emitted ahh energy by an object and a passive it is most

of the passive except that some part of microwave remote sensing which is active, but still

it does not destroy anything of the object.

So, in that way it is unobtrusive that passive remote sensing does not disturb the object

or area of interest, I can say overall the entire remote sensing does not not disturb

the objects or area of interest.

So, in that way, it is also non invasive and advantages remote sensing devices may be programmed

to collect the data systematically and such as within say 10 by 10 kilometer frame, vertical

aerial photography.

And this systematic data collection can remove the sampling bias interlude in some institute

investigations.

Nowadays, a drones are also these UAVs are also being programmed and they are they too

have started collecting data very systematically.

So, the satellites and in between the platforms between say Earth and satellite that you are

having drone, helicopters, aircraft and then different satellites in different heights.

And under controlled conditions remote sensing can provide fundamental biophysical information

including x by location, z location, and that is these other types of satellites or navigation

satellites.

Also we can get the biomass, temperature and moisture content.

Whatever the research currently which is going on on climate change, large part of or larger

data huge data or big data is coming from remote sensing sensors be the temperature

or say moisture content or say vegetation cover or a pollutants, aerosols.

All that information is coming from different types of satellites.

So lot of the data input in ahh these climate changes studies and modeling, all the data

is coming from remote sensing or from different platforms.

So this brings to the end of this initial discussion on remote sensing essentials, I

try to cover in this one, what exactly remote sensing is, and what are different platforms.

And how this whole thing works, starting from sun to satellite in between Earth and atmosphere.

And then very briefly, I have told what are ahh the other processes involved and finally,

I have also discussed in detail the advantages of remote sensing for various purposes.

So this brings to the end of this discussion.

Thank you very much.