Electromagnetic radiation and Electromagnetic spectrum. Electromagnetic Radiation. EMR is a dynamic form of energy that propagates as wave motion at a velocity of c = 3 x 1010 cm/sec. The thermal IR region is quite different than the visible and reflected IR portions, as this energy is essentially the radiation that is emitted from the Earth's surface in the form of heat. Can you take photographs in these wavelength ranges? Different objects return different amount of energy in different bands … The parameters that characterize a wave motion are wavelength (λ), frequency (ν) and velocity (c). electromagnetic spectrum –. Common wavelengths of what we perceive as particular colours from the visible portion of the spectrum are listed below. All these technologies are integrated to act as one complete system in itself, known as Remote Sensing System. There are several regions of the electromagnetic spectrum which are useful for remote sensing. One μm is about .00003937 inch and 1 μm equals 1,000 nm. Figure 1.01 below illustrates the relationship between named colors and wavelength/frequency bands; it will be a useful reference. Although many characteristics of EM energy are easily described by wave theory, another theory known as particle theory offers insight into how electromagnetic energy interacts with matter. The light which our eyes - our "remote sensors" - can detect is part of the visible spectrum. Hue and saturation are independent characteristics of colour. understanding the information to be extracted from remote sensing data. For most purposes, the ultraviolet or UV portion of the spectrum has the shortest wavelengths which are practical for remote sensing. The energy of photon is. If they did, then they would have to be cooled (and kept very cold during use), which would be very impractical. Radiation in the reflected IR region is used for remote sensing purposes in ways very similar to radiation in the visible portion. The fundamental unit of electromagnetic phenomena is the photon, the smallest possible amount of electromagnetic energy of a particular wavelength. Remote sensing, also called earth observation, refers to obtaining information about objects or areas at the Earth’s surface without being in direct contact with the object or area. Most sensing devices record information about an object by measuring an object’s transmission of electromagnetic energy from reflecting and radiating surfaces. Humans with the aid of their eyes, noses, and ears are constantly seeing, smelling, and hearing things from a distance as they move through an environment. The image is then interpreted to extract the informations about target. The energy source illuminates or provides electromagnetic energy to the target. The thermal IR covers wavelengths from approximately 3.0 µm to 100 µm. DMPQ- . Panchromatic (i.e., grayscale) and color (i.e., red, green, blue) imaging systems have dominated electro-optical sensing in the visible region of the electromagnetic spectrum. Electromagnetic radiation reveals its presence by the observable effects it produces when it interacts with matter. • EMR is a dynamic form of energy. Wavelengths are measured in micrometers (μm) or nanometers (nm). It is also used to warn people about impending cyclones. Remote Sensing. Electromagnetic waves are energy transported through space in the form of periodic disturbances of electric and magnetic fields. For the most purposes ultraviolet or UV of the spectrum shortest wavelengths are practical for... 2 Visible Spectrum. It is important to note that this is the only portion of the spectrum we can associate with the concept of colours. They should already possess an understanding that white light is the combination of all colors of the spectrum. The next portion of the spectrum of interest is the infrared (IR) region which covers the wavelength range from approximately 0.7 µm to 100 µm - more than 100 times as wide as the visible portion! Visible Spectrum. Also mention the important functions performed by the committee. Remote sensing technologies rely on a variety of electromagnetic energy. To see this page as it is meant to appear, please enable your Javascript! It also acts as a medium for transmitting the information from target to the sensor. However, modern Remote Sensing means acquiring information about earth’s land and water surfaces by using reflected or emitted electromagnetic energy. The infrared region can be divided into two categories based on their radiation properties - the reflected IR, and the emitted or thermal IR. • The whole range of EMR is called spectrum. Why is this important in remote sensing?1)Determines the spectral signal that can be remotely sensed (more absorbed energy, the less reflected to sensed). Photons, which are without mass, move at the speed of light—300,000 km/sec (186,000 miles/sec) in the form of waves analogous to the way waves propagate through the oceans. From the following definitions, we can have a better understanding about Remote Sensing: According to White (1977), Remote Sensing includes all methods of obtaining pictures or other Blue, green, and red are the primary colours or wavelengths of the visible spectrum. Principles of remote sensing Detection and discrimination of objects or surface features means detecting and recording of radiant energy reflected or emitted by objects or surface material. 6. Hue refers to the wavelength of light, which we commonly call "colour", while saturation indicates how pure the colour is, or how much white is mixed in with it. Remote sensing is extensively used in India for weather forecasting. The Remote Sensing is basically a multi-disciplinary science which includes a combination of various disciplines such as optics, spectroscopy, photography, computer, electronics and telecommunication, satellite launching etc. For most purposes, the ultraviolet or UV portion of the spectrum has the shortest wavelengths which are practical for remote sensing. The energy interaction with the target depends on the target properties and the radiation. It allows geographers to look at change over a large area over time. Sensors detect and measure electromagnetic energy in different portions of the spectrum. There are several regions of the electromagnetic spectrum which are useful for remote sensing. electromagnetic an electric field a magnetic field … is a wave that propagates (radiates) through a vacuum at the speed of light (just under 300 000 m/s) and transfers energy from one place to another … these waves carry energy as … This radiation is just beyond the violet … Sensors are also used to measure the given-off energy or emitted energy by the target; reflected-off energy of the target; or transmitted energy from the target. The light which our eyes can detect forms the visible spectrum. In addition, remote sensing takes advantage of the interaction of earth materials with various wavelengths of the electromagnetic spectrum (recall last week’s lecture). Progressive stages in remote sensing are as follows: At temperature above absolute zero, all objects radiate electromagnetic energy by virtue of their atomic and molecular oscillations. Current bathymetric and ice LIDAR generally uses green light (e.g., NASA’s HSRL-1 LIDAR, with a spectrum of 532 nm). However there are a number of electronic devices which detect and record thermal infrared images. The electromagnetic spectrum ranges from the shorter wavelengths (including gamma and x-rays) to the longer wavelengths (including microwaves and broadcast radio waves). Remote sensing data is useful in obtaining up-to-date land use pattern of large areas at any given time and also monitor changes that occur from time to time. After recording of energy, the resulting set of data is transmitted to the receiving station. Different objects return different amount of energy in different bands of the electromagnetic spectrum, incident upon it. All the components in the system work together, to measure and record the information about the target without making physical contact. The amount of radiation from an object (called radiance) is influenced by both the properties of the object and the radiation hitting the object (irradiance). Wavelength Regions Important To Remote Sensing 1 Ultraviolet or UV. When a remote sensing instrument has a line-of-sight with an object that is reflecting sunlight or emitting heat, the instrument collects and records the radiant energy.While most remote sensing systems are designed to collect reflected radiation, some sensors, especially those on meteorological satellites, directly measure absorption phenomena, such as those associated with carbon dioxide (CO 2) and … • The foundation of remote sensing technology is based on the measurement and interpretation of the patterns of EMR. The visible portion of this radiation can be shown in its component colours when sunlight is passed through a prism, which bends the light in differing amounts according to wavelength. This remote sensing method is known as Passive Remote sensing. The most important and primary requirement for any remote sensing process is to have an energy source. Electromagnetic radiation spectrum In remote sensing terminology, electromagnetic energy is generally expressed in terms of wavelength, λ. When solar energy strikes an object or molecules of the atmosphere/hydrosphere, many types of interaction are possible. The wavelengths used in most agricultural remote sensing applications cover only a small region of the electromagnetic spectrum. Remote sensing uses electromagnetic waves, such as IR band, Visible band, and Microwave band to sense the Earth’s surface. What is electromagnetic radiation (EMR)? The electromagnetic spectrum ranges from the shorter wavelengths (including gamma and x-rays) to the longer wavelengths (including microwaves and broadcast radio waves). It is important to note how small a portion of the electromagnetic spectrum is represented by the visible region. Electro-optical remote sensing involves the acqui-sition of information about an object or scene with-out coming into physical contact with that object or scene. Some Earth surface materials, primarily rocks and minerals, fluoresce or emit visible light when illuminated by UV radiation. The visible region of the electromagnetic spectrum is from about 400 nm to about 700 nm. There are several regions of the electromagnetic spectrum which are useful for remote sensing. There is a lot of radiation around us which is "invisible" to our eyes, but can be detected by other remote sensing instruments and used to our advantage. The basic components of remote sensing system are given below: The target is the object or material being studied. Although, the remote sensing includes a wide array of technologies and types, but they all are based on certain common concepts with the same basic components. The sun radiates electro-magnetic energy with a peak wavelength of 0.5 μm. There are several regions of the electromagnetic spectrum which are useful for remote sensing. Reading the newspaper, watching cars driving in front of you are all remote sensing activities. The sensor is a remote device to collect and record the electromagnetic radiation. Radiation Interaction with the Earth Different The portion of the spectrum of more recent interest to remote sensing is the microwave region from about 1 mm to 1 m. This covers the longest wavelengths used for remote sensing. It can be used to study deforestation, degradation of fertile lands, pollution in atmosphere, desertification, eutrophication of large water bodies and oil spillage from oil tankers. from different regions of electromagnetic spectrum viz., visible, infrared, thermal and microwave regions. Electromagnetic spectrum, the entire distribution of electromagnetic radiation according to frequency or wavelength.Although all electromagnetic waves travel at the speed of light in a vacuum, they do so at a wide range of frequencies, wavelengths, and photon energies. INTRODUCTION. There are several regions of the electromagnetic spectrum which are useful for remote sensing. This theory describes the EM energy as travelling in a harmonic sinusoidal fashion at the velocity of light. Detection and discrimination of objects or surface features means detecting and recording of radiant energy reflected or emitted by objects or surface material. 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