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.
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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
