Hello everyone and welcome to new discussion
today we are going to discuss different sources of free satellite images. Because, so far what we have discussed the
details about remote sensing how data is gathered and how it is processed some applications
we have also discussed, but when you start your own work and then you would be requiring
satellite images. And earlier we used to buy satellite images
which used to be very costly affair. But nowadays a lot of free satellite data
of very good quality high quality is available from different sources and of course, these
are internet sources. So, I thought that it is now discussed this
in this aspect also because now we are approaching towards the end of this course. So, before I go for the last lecture, I thought
that I will also discuss this part which is very very important and after all we have
to analyze the data we have to get the data. And from where we will get that part we will
be discussing the current sources of data. So, you know the this remote sensing or such
datasets are available of course from web portals of different agencies. And from starting from NASA, which is US agency
to European agency, ESA and ISRO also and ISRO instead of directly from ISRO we get
the data from NRSA. So, all that we will be discussing also data
from all these sources or agencies are available of the almost entire world except for a NRSA
data and available data at various spatial resolutions and various types of data various
types of data that means. The visible infrared thermal infrared data
is available and same time radar and microwave active microwave data is also available for
SAR interferometry analysis. And sometimes you also get very good software
like from European Space Agency in order to process Sentinel data or and VSAT data earlier
which was which we use to handle all the software's can also be downloaded from these sites. So, we will be will be will be discussing
in detail on those and not only one can download some of the latest greatest satellite images
But also at no charge. So, these are free of course, some of the
these web portals will ask you to get registered some will not even asked to registration and
you can just go them go on those sites search your data and you will get the link and you
start downloading. I will be showing some examples of interfaces
of such a big web portals as well. And but before you download the data, you
must know for which area you would like to download the data. So area of interest for should be decided
and that be based on that then you start searching for the data on different portals. And as I mentioned already mentioned that
the registration some portals may require registration it is generally free. So, no issue just provide your email address
name and organization and within few minutes you are having access to the data and why
these agencies go for registration of users because they would like to know that who are
using their data, how many people are using their datasets, because after all, they they
do have to be answerable to their countries or government and therefore, this is required,
there is no nothing kind of spying or anything. But just to know that who are using their
data for what purposes they are using the data. And the datasets are offered by USGS expert
earth Explorer, which is one of the very popular web portal for downloading the data of USGS
that is United States Geological Survey, which offers abundance of datasets various datasets
are available from this web portal. And they acknowledge world supporter for of
free data providers, access to Landsat satellite data. So this USGS earth explorer there are various
web portals may provide even the same type of data. So, it is as per your convenience, because
different web portals are having different kind of web interfaces to search and download
the data. So, the one in which you like you can start
downloading the data that means what I am trying to say the like for example, Lansat
data, you will let us data maybe I will label on 3 4 portals. So, there is a it is not necessarily that
only USGS you will download you can download from other also. So access to the satellite data because the
Landsat data is very popular one and there is continuity from 1972 onward. So more than 40 years of history of this Landsat
data is available in many spectral bands for entire globe. And also you can download the Aster data and
settle topographic mission. That is SRTM also data of that is and Digital
Elevation models. So 2 different Digital Elevation models and
that too and too many spatial resolutions like ASTER and SRTM dem's can also be downloaded
from Earth Explorer, NASA land data products and services includes Hyperion's hyperspectral
data as well. So, the when we have been discussing hyperspectral
remote sensing at the time, I mentioned that there is only one satellite which is Hyperion
and that can provide the data. So, Hyperion data is also available, but it
may not be available for the entire globe in a continuous fashion as compared to Landsat
data. But nonetheless, some datasets for your own
analysis and interpretations and having experience of processing such data are also available
and very other popular data on daily basis because the coverage of the globe on daily
basis by MODIS and AVHRR sensor. And MODIS is one Terra and of Aqua satellites
AVHRR one NOVA series of satellites. So the datasets of land surface reflection
and dispersed radar data can also be downloaded from USGS. So USGS earth explorer is one of the biggest
resources of such datasets. When you go and open this web portal. This is how you start getting the interface. And then on the left side, there are various
options are available. You just go and download the data, make your
query, search for results, provide your location, search the data and once that is there, you
get the data And the links available and then you can download
the data. The next very popular and resource web resource
that is the ESA and that 2 for the Sentinel data and you know both normal data that is
visible infrared data as well as your radar data, interferometry data can also be downloaded
from European Space Agency. And that is a satellite datasets Sentinel
datasets and Sentinel 2a and 2b have higher spatial resolution that is 10 meter visible
and infrared that is also available free of cost. You can also download Sentinel and high quality
passive and active data that is microwave data active data microwave data interferometry
data. And this Sentinel 2a to 2b data is available
in 12 spectral bands of entire globe and this is what the C band synthetic aperture radar
interferometry datasets from Sentinel 1 for for entire world. It is available. Let me give you very latest Example of about
this dataset, how useful it is that only very recently there were earthquake in Pakistan
occupied BOK. And we wanted to analyze the ground deformations
which might have induced by and that particular earthquake. And we just downloaded as pre earthquake and
post earthquake data and in within few hours we could do the analysis and prepare the ground
deformation map very accurately and very promptly so that is the advantage of having and datasets
from ESA of the sentinel one active microwave interferometry data. And also it is free of cost it is available
quickly once the data has been acquired within few minutes it is available on the portal
for downloading, so this is how when you go on this side this is how you get the Copernicus. Open access hub and there you start searching
the data lot of options are there and once say you are sure that you want to download
the data click on the link. and get on your machine now another web portal
which is NOAA class is there which currently NOAA and that is national data centers NDC
supports POES data. DMSP, DMSP is the passive microwave remote
sensing data then GOES data, me topped me me metOp data, JSON data and many data are
there but these data generally are having relatively coarse at resolution data so if
you are working on continental scale. Then these datasets can also be downloaded
and they also provides the archive data collection most of these sites will provide you archive
and from NP NPP, JPSS. And earlier we used to know about and pause
and GOES-R jason-3 and many other data satellite data which might be available in future high
quality atmospheric datasets can also be downloaded From these as this is what is again the NOAA
site NOAA class site about this class is here and you can create a user account and then
start downloading the data the best practice if you are looking for ground data as a ground
for the satellite data is to spend some time on individual portals and they explore the
portal exhaustively and I am sure that after say half an hour or one hour you would be
very comfortable you would know where exactly. I have to go and search the data and from
where I will download so just going first time may me me give you impression that is
too heavy to search for the data so the best thing is spend some time and in half an hour
time or one hour time you would we you are going to be comfortable with that particular
portal and you start downloading the data now there is a another portal by NASA earlier. We saw the USGS that was also from USA NASA
is also from USA that is earth data search is available as a use archival data is available
of various satellites and it is I tell you this very good portal for getting free data
and that data provides Aqua, Terra that is MODIS data of Aqua ,Aura and TRMM and NASA,
DC, ENVISAT data, METEOSAT data, GOES, Landsat SMAP and the many many such datasets are available
from these including data from GPS satellites. And for various kind of analysis sometimes
you might be requiring the data so that dataset can also be downloaded from earth data search
and as I am already mentioned that user may find initially bit difficult to navigate and
then to search the datasets this this is general impression
this is how the experience the first time visitor experience ended oh it is too cluttered
it is having too much difficult to navigate through different options. But as I said the best practice is spend some
time on that web portal I am sure in half an hour one hour time would be very comfortable
there are various base of narrow down search 30 ways to narrow down search, so various
options are available how to find out the best data so we start with a simple search
the first best practice for such a you know big portals and then change the time range
criteria. You go to that time which for which you you
are looking for the data further narrowed answers and finally download free satellite
datasets. So that that is we and you can you can be
very comfortable this is the interface of that EARTHDATA search a portal various datasets
are available and various ways you can search 30 ways here you type here location of any
part of the globe that location will come you can use your geographic search you can
use some polygons overlay add that layer and overlay that one and then you get the and
the appropriate data whichever. You are looking say for example I am looking
for NOAA data I might get the indices of NOAA data or links of NOAA data and then I go for
download. There is another web portal for different
type of satellite data that is Earth Observation Link EOLi in sort that is European Space Agency
client for Earth observing catalog and ordering services and one can preview most of these
web portals so far which we I have discussed will allow you to see the data in a quick
look format that is in preview format before you download that it advantage of that one
that you can assess the cloud coverage initially. And you can also know roughly that whether
your area of interest is being covered in that particular scene which you have selected
for download or not because before and avoiding preview and just downloading the data and
later on on your system you are seeing and the image you find that it is not covering
your area it is having cloud cover it would be a stage your time so the good practice
is once you have selected the data look for the preview most of these porters will prove
and portals will provide the preview have a look spend some time zoom it. And once you are sure then you go for download
link so this Earth Observation link provides the data of Envisat, ERS, IKONOS, DMC, ALOS,
SPOT, Kompsat, Proba, SCISAT even IRS data need not to be directly from NRSA but from
other organization of different countries. So in that way you can have the data access
to the data IRS data is generally available free of cost only after 3 years of data acquisition
and there are various searches downloading may be little slow For this portal this is how it looks like
how to access the data sometimes you also get the tutorials available so you can spend
some time on tutorials learn a quick way best way to download that Search the data and then
download the data. So these are the web portals for that now
a one more about portal which is National Institute for Space Research INPE is available
that is a partnership between Brazil and China has their own image catalog of remote sensing
or satellite data which allowed to download such datasets and these datasets include the
China - Brazil Earth Resources Satellite 2 and 2b and these CBERS-2, CBERS – 2b all
these satellite data is available it also includes satellite from the United States,
United Kingdom. And other countries and other satellite including
India data from Aqua, CBERS, Landsat see the Landsat, Landsat data might be available from
various web portals sometimes one web portal might be having only the older data may not
be the latest data or some web portals might be having the entire dataset so you have to
search and find just making search on one web portal and thinking that is the only dataset
available from Landsat will not be sufficient. So all these their resources web resources
should be searched and then you get the data the source set is of course Indian data which
is also available and Terra, Aqua data, UK DMC data all kinds of data is available one
has to be little careful sometimes and the web portals might not be in English, so you
have to get a translated from Portuguese to English. Those options are available like here this
is the example that it is in Portuguese and you can definitely get it translated through
web only that is not a big deal. Now come to our own Indian and web portal
for downloading the data and the web portal is our Bhuvan earlier Bhuvan used to require
the registration and only later we used to get the access to the data now it is registration
free and you have to basically install in an app earlier now even you do not have to
install the app and directly it will open and do it so it easily basically as I said
it has in really big strides in in satellite remote sensing technology because earlier. We were buying each and every dataset from
an RSA and DC that is national data center of an RSA now most of the dataset is available
older datasets is available free of course from this web portal that is Bhuvan and datasets
up to 1988 because that is the first time when we launched our own Indian remote sensing
satellite IRS-1A, so onward 1980 it is was the month of March so March 1988 onward. And data on this web portal is available and
super and Geo Platform is this is the India’s Geo Platform and so most of the data is for
India only as I have mentioned earlier also that the Bhuvan provides data only for India
and may be little bit on the surrounding countries that data can be downloaded it includes the
Hhyperspectral IMS data also to limited extent not fully for entire country it has in have
a data on Cartosat it is having Oceansat, ResourceSat. And Cartosat derivatives that is digital elevation
models at a higher spatial resolution maybe 5 meter resolution available on this site
as well and these are the products which are available and derivatives not only the raw
data but derivatives like NDVI and for entire India or part often India global coverage
and a CartoDem that is Cartosat digital elevation model and available for SAARC countries and
some Climate products are also available for North Indian Ocean region
also. This is how it will look when you go for the
web portal and using this address then you get the this kind of thing as I mentioned
India and little surrounding countries are there so up to Pakistan and maybe up to Sri
Lanka here you search here you make the search you that what you want to download whether
you want to download satellite data or products or program projects and accordingly you will
go and make the search you can have with a latitude longitude use the grid there are
different search options are available. And then finally the link would be available
for download like here and you can also download the handbook you can also download the Cartosat
Brochure and other things for detailed information about these products. Now this is Japanese agency that is JAXA’s
Global ALOS 3D world and they say say 30 meter spatial resolution digital surface model or
you know because the technique has been different so there instead of calling digital elevation
model and they would like to call as digital surface model and that means that objects
like vegetation and other things are not included and may one may find this at this resolution
a very accurate digital elevation model from a ALOS, satellite. And this DSM has been made available to the
public 30 meter which is quite good is a global scale digital elevation model and this this
time using the Advanced Land Observing Satellite that is DAICHI or also called ALOS PULSAR’s
L band that is microwave data that is wide it have been possible to go for DSM digital
surface model if we go for stereo pairs like Cartosat then you can produce the digital
elevation model but when we go for radar data then it is possible to get the digital surface
model rather than digital elevation model. So this is this can be and many application
one can find DSM is much more accurate than a simple DM the JAXA’s or mosaics are excellent
development for global elevation models this is how it will look ALOS 2 ALOS and global
digital surface model DSM and 3d world and that is a 30 meter resolution so again similar
way almost the search part in most of these portals are almost same. You need to have a corner latitude longitude
coordinates and rest let us say that you can manage very well. So it is not very difficult to search for
the data if you are having already area of study in form of polygons most of these portals
will also allow you to add your polygons and based on that polygon the search can be made There are some other web portals and which
one can go explore and can get the data which you might be looking like NOAA dataset access
viewer that is discover authoritative datasets and this is the address then VITO Vision Coarse
Vegetation Data if somebody is working on vegetation change and DVI and other things
so relatively coarse resolution spatial resolution data might be available then NOAA digital
coast. If somebody is working on coastal area that
data can also be available global land cover facilities that is derived satellite data
that is also available. And then digital globe free product samples
are also sometimes say this digital globe will provide very high resolution satellite
images very high resolution might be you know 60 centimeter or 1 meter but only sample data
are throughout but if for certain purpose. If sample data is sufficient you can still
download then there is Geo Airbus intercontinental champions of satellite imagery so there are
various other portals are also there apart from a NASA, USGS, ESA in Bhuvan there are
other portals from where you can download the data. So happy downloading data
