In much of remote sensing, the process involves an interaction between incident radiation and the targets of interest. The suns energy is reflected for visible wavelengths, or absorbed and then re emitted for thermal ir wavelengths for all reflected energy, this can only take place during the time when the sun is illuminating the earth. The sun is the major source of energy, radiation and illumination. Remote sensing in the thermal infrared portion of the electromagnetic spectrum is an example of passive emitted remote sensing. Nasas observatorium remote sensing is the science and to some extent, art of acquiring information about the earths surface without actually being in contact with it. Once remote sensing data have been collected, the user must interpret the data to derive the information needed to help make decisions. This guideline explores some of the basic analysis options for agricultural applications of remote sensing data. These satellites are known as remote sensing satellites e.
Detection and discrimination of objects or surface features means detecting and recording of radiant energy reflected or emitted by objects or surface material. Remote sensing is the common name for all methods used to collect data at a distance from the object under study by some kind of recording device. Introduction and scope of remote sensing owlcation. Role of the atmosphere all energy reaching the remote sensing instrument must pass through a portion of the earths atmosphere. This energy is in the form of electromagnetic radiation. However, modern remote sensing means acquiring information about earths land and water surfaces by using reflected or emitted electromagnetic energy. Different objects return different amount of energy in different bands of the electromagnetic spectrum, incident upon it. Remote sensing, in its third edition, seamlessly connects the art and science of earth remote sensing with the latest interpretative tools and techniques of computeraided image processing. This involves the detection and measurement of radiation of different wavelengths reflected or emitted from distant objects or materials, by which they may be identified and categorized. The main difference between thermal infrared and near infrared is that thermal infrared is emitted energy, whereas the near infrared is reflected energy, similar to visible light. Passive remote sensors measure radiant energy reflected or emitted by the earthatmosphere system radiant energy is converted to biogeophysical quantities such as temperature, precipitation, soil moisture, chlorophylla examples. May 24, 2015 remote sensing is the art and science of acquiring information about the earth surface without having any physical contact with it. Special cameras collect remotely sensed images, which help researchers sense things about the earth. Passive remote sensing the sun provides a very convenient source of energyfor remote sensing.
Apr 23, 2017 the first requirement for remote sensing is to have an energy source to illuminate the target unless the sensed energy is being emitted by the target. The foundation of remote sensing technology is based on the measurement and interpretation of the patterns of emr. Preface remote sensing data is one of the primary data sources in gis analysis. Remote sensing systems, which measure this naturally available energy, are. Physical principles of remote sensing earth online esa. In quantitative remote sensing, the user must be aware of t he physics of those energy matter interactions as well as the spectral features that result. Pdf introduction to remote sensing systems, data, and.
This is done by sensing and recording of reflected and emitted energy. Remote sensing is the process of gathering information about something without touching it. Image analysis is the science of interpreting speci. From the following definitions, we can have a better understanding about remote sensing. The objective of this material is to provide fundamentals of remote sensing technology and its applications in geographical information systems to undergraduate students and the one who wants to study about remote sensing technology by visually read less learn more. Remote sensing uses a part or several parts of the electromagnetic spectrum.
The use of remote sensing techniques is increasing rapidly, finding new fields of application as technology advances in developing the remote sensing systems. Remote sensing is the science of acquiring information about the earths surface without actually being in contact with it. Remote sensing typebased on source of energy the sun provides a very convenient source of energy for remote sensing. Newly expanded and updated, this edition delivers more of the applied scientific theory and practical results that helped the previous editions earn wide. Plancks radiation law stefanboltzmann law wiens displacement law theoretical background absorbed emitted radiationradiation thermal infrared remote sensing. Remote sensing is defined as the art, science and technology through which the characteristics of objectstargets either on, above or even below the earths surface are identified, measured and analysed without direct contact existing between the sensors and the objects or events being observed see, e. Emr transmit cross space in the wave form and in the speed of light. Remote remote sensors record solar radiation re ected or emitted f rom the earths surface. Topology describes the geometric characteristic of objects which do not change under transformations and are independent of any coordinate system. Remote sensing is the process of detecting and monitoring the physical characteristics of an area by measuring its reflected and emitted radiation at a distance typically from satellite or aircraft. It records the electromagnetic energy reflected or emitted by the earths surface. In the process of remote sensing involves an interaction between the incoming radiation and interest of target.
The earths climate is largely determined by its energy budget. The sensors recording the energy that they receive are placed in a near polar sun synchronous orbit at an altitude of 700 900 km. In this latter case, the source of energy is the target material itself and the sensor records primarily emitted radiation. Elements of remote sensing multiple choice questions. Detection of reflected emitted energy by the sensor. Initially cameras were used to take photographs on the ground, which provided and still does a fascinating and exciting way to capture moments in time and keep a record of something that happened, which looked more realistic than a drawing or painting. Electromagnetic radiation emr basics for remote sensing.
According to white 1977, remote sensing includes all methods of obtaining pictures or other. Note, however that remote sensing also involves the sensing of emitted energy and the use of nonimaging sensors. At any given moment our sun is bombarding the earth with a variety of wavelengths of emr, including visible light, infrared, radio and microwaves. Haefliger, arctic ice surface temperature retrieval from. This is done by sensing and recording reflected or emitted energy and processing, analyzing, and applying that information. The suns energy is altered in intensity and wavelength by particles and gases in the earths atmosphere. Hyperspectral refers to a variety of remote sensing techniques that collect reflected or emitted electromagnetic. The amount of emr and the wavelengths emitted depend on the temperature.
According to white 1977, remote sensing includes all methods of obtaining pictures or. Trmm microwave imager, modis, airs trmm tmi 85 ghz microwave image cimss. Remote sensing and geographical information system gis. The main s ource of energy for remote sensing comes from the su n. Since the 1960s, satellite remote sensing has been used in estimating these energy budget components at both the top of the atmosphere toa and the surface. Remote sensing is a technique to observe the earth surface or the atmosphere from out of space using satellites space borne or from the air using aircrafts airborne.
Study guide electromagnetic spectrum everything with heat 0 k with heat 0 k emits electromagnetic radiation emr emr is a combination of electrical and magnetic waves waveform sinusoidal speed of light c c3x108 msec c. While most remote sensing systems are designed to collect reflected energy, some. Radar and other active remotesensing systems usually emit prof. Fundamentals of remote sensing introduction natural. The technology of modern remote sensing has a very long history, dating back to the end of the 19th century with the invention of the camera. Passive remote sensing can also be carried out in the absence of the sun. Water resources mapping estimation of the hydrometeorological state variables and fluxes applications of the remote sensing data in water resources management under each section, details of the sources of global remote sensing data products, if any, are. The first requirement for remote sensing is to have an energy source which illuminates or provides electromagnetic energy to the target of interest.
Most remote sensing applications make use of the 3 to 5 and 8 to 14 micrometer range due to absorption bands. Electromagnetic radiation emr and its application in remote. This is done by sensing and recording reflected or emitted energy and. Remote sensing is the science and art of identifying, observing, and measuring an object without coming into direct contact with it. These changes appear on the image in ways that degrade image quality or influence the accuracy of interpretation.
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