Hello hello everyone this is Arun Saraf from department of Earth Sciences IIT Roorkee and
we are going to start a new course on introduction to Remote Sensing Earlier I have also done
the course on introduction to Geographic Information System and I would like to link these two
courses with a word (aa) technology word which is called geo informatics and geo informatics
constitute three technologies one is remote sensing another one is GIS ie geographic information
system and third one is nowadays is very popular is and navigation system or global position
system
Now these three technologies are having three things in common First of all these three
things and technologies are digital secondly they are special technologies that means they
are all related with the location location specific data handling and other things and
third one all these three technologies are generic and that means that you can apply
to (as) as if one can think and the application area
So that is the best thing is that all these three technologies are getting nowadays integrated
with other technologies like communication and other things and overall these technologies
are becoming very powerful tool for and (and) in natural resource management disaster management
and so many other application So first (aa) as I mentioned we are going to now discuss
(ahh) all this (ahh) subject that is remote sensing in detail in next 20 lectures
So first we will see that what is basically remote sensing technology we know that (aa)
in all we go by the definition that is a (re) acquiring information or data about the Earth
surface without actually being in contact with it And the best example of the motion
is our eyes we (abs aa) many things we observe through eyes without even touching them but
our eyes are not sensitive in all parts of electromagnetic spectrum our eyes are only
sensitive in visible part of electromagnetic spectrum and therefore we use as a human we
use a very small window of electromagnetic spectrum which we will see in later lectures
in detail
But there are some animal and words which are more sensitive in other parts of electromagnetic
spectrum and one (aa) we consider as (bembel aa) mammal and that is your tape which have
got a different kind of remote sensing and and it is having different kind of remote
sensing technology that means it sense a eco-pulses and whatever in return it records it and base
on that is basically make the assessment about a tape this is how it works
So our eyes are only sensitive in visible part not in infrared or thermal infrared that
means through distances by looking the object you cannot assess the temperature of that
object unless we know some other background information
And this is a as you know now days there are various type of satellite are in space and
what these satellites are doing basically they are recording whatever the reflected
or am meted energy (reflecte) for reflected energy you basically require some source and
the best source for us is available is the sun
So sun in during day time you know illuminates the part of the Earth and then whatever the
reflected energy which reaches to the satellite is recorded Emitted energy is as you know
all natural objects which are having temperature above absolute zero also emitted energy and
that energy can also be recorded in thermal part of electromagnetic spectrum so that we
will see later
And in over all remote sensing what we do we do recording of a reflected or emitted
energy we do the processing remote sensing also involves the analysis of remote sensing
data and finally it is a and last that is not the least is the application part how
to apply How to use these data set which is huge data set now it is available from various
type of satellites in for as I mentioned for natural resource management disaster civil
engineering you name it now days people are using for (aaa) various application
So first as you can see here that there is a illumination source which is source which
is some is available to us and then we are having a satellite and then there might be
a different type of satellite then we are having a ground station and then we are having
recording facility analysis facility at the ground So first as I have mentioned for this
reflecting remote sensing we required energy source that Sun is available for us and the
radiation and the atmosphere in between and the (aa) we are having between the Earth and
the Sun we are having these phenomena
Especially the atmosphere and then whatever the interaction it has it has with the front
objects like for example if the solar energy is falling on water it will have a different
reflections if it is falling on the bear ground it will have a different if it is on it will
have different So the interaction with target is also important and that makes with the
basis of basically the image making and image inter potential and analysis and this what
we do after this reflection and then again going through the atmosphere finally it is
recorded by the satellite and these satellite then which are having different type of sense
which we will see later
Then this involves the transmission of data from satellite to ground Earth stations or
different satellites and finally you do the processing and analysis and then of course
interpretation and analysis are very very important because lot of now days data is
available but not much analysis or interpretations are being done And the new innovations are
always required integration with other data sets are also required while doing interpretation
and analysis So this set basically covers the entire remote sensing in a nut shell and
of course as I have mentioned application are there people are developing new applications
are been developed very regularly almost every day
As you know that within one day the current or the present day remote sensing didn’t
not start it took a lot a lot many years and we will see the history as well So that remote
sensing is also consider when we are using helicopters or aerial aero planes which is
consider as aerial photography and later on we started putting our sensors also there
on the aero planes and then we are having optical sensors or other sensors through the
satellite and having different distances like your helicopters are might be at 300 meter
400 meter or 1 kilo meter where as aerial photographic can be done from higher space
Then you are having very high distance surface of the Earth about the satellites which are
mainly polar orbiting satellite I am talking Then might be some times they are having Space
Shuttle vision and which are may not be at that height as 700 to 900 but maybe between
185 to 575 and then there are another for SAR Interferometry or some data remote sensing
we use are different Now days one more thing we can add here is now at these a UAV unmanned
vehicles are also been use (ana aa) remote sensing as well
As I mentioned earlier that now days the Earth is envelope with hundreds of satellite launched
by different countries as you can see the cluster of different satellites are there
our inset satellites is also here and there NOAA satellites which started in 70’s and
then many many satellites are there and which this is F51 to 3 F52 to 4 and these where
the Chinese satellite and so on so forth And there if you will see carefully you would
find that there are 2 3 types of orbits are also sole at different distances So this is
just a representative that how Earth is being enveloped by different types of satellite
which are orbiting around the Earth Some of them might not be working or there are many
many many more satellites which are working which are not sole in this figure
Now as we progress further in this that the remote sensing process involves an interaction
between incident radiation and targets of interest and in this case when we are having
regular satellites orbits the target of interest is been scanned on very regular basis depending
on the height of the satellite depending on special resolution of the satellite these
targets of interest are being recorded And then this is exemplified by the use of imaging
system most of these system we are not having a like digital camera like a snap shot except
a neurological satellites like inset or these communication satellites where we are having
snapshots otherwise we are having imaging system which scans line by line or part of
the Earth and then transmit the data towards the earth through Earth station we record
the data we interpret the data analyze the data and make different applications
Now as you can see that for these reflected remote sensing or specific remote sensing
we require a source of energy which is Sun is there and there is one satellite in sole
and this energy of the Sun has to travel from the and atmosphere through the atmosphere
It reaches on the different types of the object which is present on the Earth which is starting
from the building and may not be very high building and maybe the road bare soil grass
water bodies forest and different type of objects are there
Then these reflected energy reflected solar radiation has to go back again to the satellites
through this atmosphere and lot of changes might also occur lot of errors maybe introduce
during these transmission or (aa) this reflected radiation from the Earth toward the satellite
So that is also how to correct it how to improve our images that is also done in a digital
image processing or satellite data So that is also part of remote sensing
Now as a one by one we will go as A is the illumination source which is shown there as
a Sun which a first requirement for remote sensing is to have a energy source without
that energy source we cannot have a illuminations or we cannot have recordings of any targets
of interest And as I also mentioned that if you don’t have the illumination source the
natural emittance or the natural emission of energy which is coming out of the different
object may also work there
So that also there then we are having the radiation and atmosphere as I have mentioned
that the solar radiation which reaches to the Earth has to go back to the satellite
through again the atmosphere So there is B component which is shown in this figure as
the energy travels to the source to its target it will come in contact and interact with
the atmosphere So initially it will interact and then it passes through and this interaction
may take place and may take few seconds as a energy travels from target to the sensor
so we are more concern when our solar radiation or reflected energy is going back from the
Earth surface towards the satellite because that is what which is recorded by the satellite
and that is what it creates the problem for us
Suppose if there are clouds in during the day time in this passive remote sensing
this reflecting part the clouds will create problem and then what satellite will record
satellite will record clouds not the part of the Earth so this is the major issue so
the atmosphere plays a very very important role while this solar radiation reflected
solar radiation reaching towards the satellite
Then a the C component is the interaction with the target so their once the energy hits
or the solar energy hits the object that makes it get through the target through the atmosphere
it interacts with the target depending upon the properties of the both the target and
the radiation here the properties as I have mentioned just two slides back that whether
this a solar radiation is falling on a building or a bear soil or a rocket sources or water
bodies or vegetation it will behave differently and therefore the signature which it will
reflect towards the satellite are also going to be different and this makes basis on our
image which will show these object in different in digital values basically and we assigns
these different values different colours so we see things in different colours
And the D component is recording of energy by the sensor once the this reflected solar
energy reaches to the satellite it is recorded by the sensors which are present and the recording
system which are on board of the different satellites so after the energy is been scattered
by or emitted as I have also mentioned earlier that a once this energy goes through the atmosphere
through the satellite it has to pass through the atmosphere and this then create some problem
Like their might be some absorptions their might be some scattering and different types
of scattering which we will also see later and which requires a sensor remote not in
target to collect and record the electromagnetic radiations so you require a require a complete
recording system on board the satellite and there are satellites of also which not only
records but the same time they also transmit the data towards the Earth
So if you are having a appropriate set up for recording this data and live also simultaneously
once the part of the Earth is being scanned by the satellite the same time the data is
been recorded by the satellite and also it is directly being broadcasted towards the
Earth stations and that can also been recorded so immediately we get the data about that
particular part of the Earth for which the satellite is over passing And the last one
here is E E component that is transmission research and processing
So transmission is done by the satellite the energy recorded by the sensor on board of
satellite has to be transmitted or recorded then often it is in electronic form that is
digital form then it has to be received by Earth stations which are spread over the different
parts of the Earth in different countries processing station is required the data some
initially processing done and later on some advance processing or digital image processing
of that data is also done Some people may go for hard copies or now days more popular
one is a digital image processing
Now one after these you come with the F component that is the inter potential analysis so that
the image which is recorded on the sensor of board of the satellite may not show initially
the object which one might be looking or the differentiation between the object and therefore
lot of processing is required First processing is to correct do the correction of radio metric
corrections their might be some problems about the sensors scanners and those things has
to be corrected
Generally these things has to be corrected by the operators of those satellites or Earth
stations then their comes analysis part the comes the how to remove the atmospheric distortions
because the reflecting energy is going through the atmosphere and this causes the lot of
distortions in the data ultimately the images and these has to be removed so that our image
becomes much more sharp or much more useful interpretable
And then these there are some other advance image processing which are applied and ultimately
we go for a better recognition or classification of images and we prepare using a satellite
image we can prepare a forest density map using a satellite we can make land use map
or may be ethological map or structural map all kinds of map then can be derived using
remote sensing data
So we put all this in interpretation and analysis and finally the G component that is application
that is the most important one is the data is there every set up is there but the data
has to be applied data has to be used somewhere Now there are lot of applications are there
people are employing data or a you’re a even weather forecasting weather monitoring
if you are having the long term data then climate change people are using the data and
for applications like simple preparing land use land cover maps for forest cover
maps for vegetation density maps even for agriculture production forecasting what is
going to be the output through (rodi) ready crop or a wheat crop and so on and so forth
Maybe mineral exploration maybe in oil exploration water exploration so in a they this is a long
list of applications some of the application may be is still not been developed or explore
and I am sure with more data and more type of different type of sensors people will explore
more application of remote sensing as well So depends were we and most important thing
whenever there is a disaster occurs whether it is a flooding or earthquake or landslide
first thing people look remote sensing data and that is the true very good application
of remote sensing because of these disasters the first causality is the communication
The communication becomes very weak or very poor and there forth you have to do some (aaa)
you have to find some information for rescue and rehabilitation only that is possible now
days through remote sensing So that is the data is the first look for remote sensing
data So this brings the basically very brief the introduction of remote sensing In this
course in next 19 lectures we will be seeing all this things components in much more detailed
we will start with different parts of electromagnetic spectrum and we will end different applications
few examples is will show that how remote sensing can successfully being implied for
water resources maybe for earth quake related studies and so on so forth Thank you very
much