REMOTE  SENSING  

           Remote sensing is the science and art of obtaining information above an object area or phenomenon through the analysis of data acquired by a the device that is not in contact with the object area (or) phenomenon under investigation.

 what is Remote Sensing: 
                                            The science and art of Obtaining Information about an area, and phenomenon, without being in direct contact with the feature under investigation.

                 As you read these words you are employing remote sensing you are acting as sensors that respond to the light reflected from this page. The data your eyes acquire are impulses corresponding to the amount of light reflected from the dark and light area on the page.

        These data are analyzed (or) interpreted in your mental computer to enable you to explain the dark areas on the page as a collection of letter forming words beyond this you recognize that the words form sentences and you interpret the information that the sentences convey.

               In many respect remote sensing can be thought of as a reading process using various sensors we remotely collect data that analyzed to obtain information about the object, areas,      (or) phenomena being investigated the remotely collected data can be of many forms including variation in force distribution acoustic wave distribution (or) electromagnetic energy distribution for example a gravity meter acquires data on variation in the distribution of the force of gravity sonar like a bats navigation system obtains data on variation in acoustic wave distribution  our eyes acquire data on variations in electromagnetic energy distribution.

            This book is about electromagnetic energy sensors that are currently being operated forms airborne and space borne platform to assist in inventorying mapping and monitoring earth resources these sensors acquire data on the way various earth surface feature emit and reflect electromagnetic energy and these data are analyzed to provide information about the resources under investigation.

             Picture:1 schematically illustrates the generalized process and elements involved in electromagnetic remote sensing of earth resource the two basic process involved are data acquisition and data analysis the elements of the data acquisition process are energy sources (a) propagation of energy through atmosphere (b) energy interactions with earth surface features (c) retransmission of energy through the atmosphere (d) airborne and/or space borne sensors (e) resulting in the generation of sensor data in pictorial and/or digital form (f) in short, we use sensor to record variations in the way earth surface features reflect and emit electromagnetic energy. The data analysis process (g) involves examining the data using various viewing and interpretation devices to analyze pictorial data and/or a computer to analysis digital sensor data. Reference data about the resource being studied (such as soil maps, crop statistics, (or) field –check data) are used when and where available to assist in the data analysis. With the aid of the reference data, the analyst extracts information about the type, extent, location, and condition of the various resources over which the sensor data were collected. This information is then compiled (h) generally in the form of hardcopy maps and tables (or) as computer files that can be merged with other “layers” of information in a geography information system (GIS). Finally, the information is presented to users (i) who apply it to their decision – making process.

                                               In the remainder of this chapter, we discuss the basic principles underlying the remote sensing process. We being with the fundamentals of electromagnetic energy and with then consider how the energy interacts with the atmosphere and with earth surface features. Next, we summarize the process of acquiring and interpreting imagery in both analog and digital formats. We also discuss the role that reference data play in the data analysis procedure and describe how the spatial location of reference data observed in the field is often determined using Global Positioning System (GPS) methods. These basics will permit us to conceptualize the strengths and limitations of “real” remote sensing systems and to examine the ways in which they depart from an “ideal” remote sensing systems. We also discuss briefly the rudiments of GIS technology. At the end this chapter, the reader should have a grasp of the general concepts and foundations of remote sensing and an appreciation for the close relationship among remote sensing, GPS methods, and GIS operations.

        Picture:1 Electromagnetic Remote Sensing Of Earth Resources

Marginal Information Of Satellite Imagery

SD     :  Product Types Browse/ standard

25/nova/97      :  precision time Date/month/year

L2A        :  camera identification (liss 1,liss2,liss3)

Liss         :  Linear Image Self Scanner

I              :  Subscene Identification(IOR)

B234       :  Band number (b1,b2,b3,b4) 

G2             :  Gain settings (G1,G2,G3,G4,G5) 

Po23 E61    :  plat number, Row number

FN10 56 16/E  : Formal center of culture and Longitudes 

S68 001      :  sun Election are the lime of imagery

HYD           :  Data receiving station

16APR 97 : Product Generation date 

ISRO/NRSE  : Product Generation Agency

IRS1             :  Identification   , satellite. 

Elements of Aerial Photo Interpretation

1)  Fiducial marks   2)  Date Of Photograph           

3)  Vertical cavel

4)  Time 

5)  Flyers Height /infeed

 6)  Altimeter

7)  Facet Legit

8)  Task Number

9)  Flying Agency

10)  Ran/Path Number

11) Exposure Number

12)  Photo Number

Types Of Aerial Photography

A)  Terrestrial Photography

B)  Low Oblique Photography

C)  High Oblique Photography

D)  Vertical Photography 

E)  Convergent  Photography

F)  Trimetrogon Photograph 

G)  Close Range Photography

H)  Long Range Photography

I)  Panchromatic Photography 

J)  Color Photography (Black/White)