Remote Sensing Course - Academic Year 2024-2025 Fall Semester PDF

Remote Sensing Course Academic Year 2024-2025 Fall Semester BY: Dr. Dleen M. S. Al-Shrafany References recommended for this course : 1- Campbell, J. B. 2002 “Introduction to Remote Sensing”; 3rd edition, New York, USA. 2- Lillesand, T.M., Kiefer, R.W. and  Course Structure L...

Remote Sensing Course Academic Year 2024-2025 Fall Semester BY: Dr. Dleen M. S. Al-Shrafany References recommended for this course : 1- Campbell, J. B. 2002 “Introduction to Remote Sensing”; 3rd edition, New York, USA. 2- Lillesand, T.M., Kiefer, R.W. and  Course Structure Lecture Two-hours period lecture per week, students are encouraged to take careful notes based on lectures. These should include noting remote sensing referenced in class, key concepts and definitions, core concepts related to data gathering, image interpretation and image analysis. Lab The lab exercises are aimed at reinforcing core concepts, themes, and skills introduced through the lectures and readings. Students will engage in hands on experiences that involve: 1- analysis of remotely sensed images, 2- use of web-tools to learn concepts related to remote sensing applications, 3- organizing and visualizing spatial information. Students will also complete: 1- computer based assessments, 2- lab reports, and 3- web search during their lab sections. Labs will be implemented by the graduate research assistants involved in the instruction of this course. Each lab will begin with a brief explanation of the lab assignment by the TA, including an overview of the learning objectives and materials, The remaining portion of the lab will devoted to completing the lab assignment.  Part I: Foundations 1- History and scope of remote sensing definitions overview of remote sensing process key concepts of remote sensing 2- Electromagnetic radiation the electromagnetic spectrum radiation laws Interactions with the atmosphere three models for remote sensing  Part II: Image Acquisition 1- Photographic sensors the aerial camera Geometry of the vertical aerial photograph Coverage by multiple photographs Digital photogrammetry sources of aerial photography review questions 2- Digital data electronic imagery Spectral sensitivity data formats equipments for digital analysis image processing analysis review questions 3- Image interpretation the context of image interpretation Elements of image interpretation Image interpretation strategies Image interpretation keys image interpretation equipment interpretation of digital imagery review questions 4- Active Microwave and LIDAR active microwave geometry of the radar image Wavelength and Polarisation interpreting brightness values Satellite imaging radars LIDAR review questions 5- Thermal radiation thermal detectors thermal radiometery microwave radiometers thermal scanners thermal properties of objects geometry of thermal images heat capacity mapping 6- Image resolution definitions target variables system variables measurement of resolution spatial and radiometric resolution Interactions with the landscape  Part III: Analysis 1- Pre-processing feature extraction radiometric pre-processing Image matching geometric correction by resampling map projection for representing satellite images data fusion 2- Image classifications informational classes and spectral classes unsupervised classification supervised classification textural classifiers relative accuracies of classification 3- Field data kinds of field data nominal data biophysical data field radiometery locational information geographic sampling 4- Accuracy assessment definition and significance sources of classification errors error characteristics measurements of map accuracy interpretation of the error matrix  Part IV: Remote Sensing Applications 1- geographic Information System (GIS) 2- Land use and land cover 3- Earth Sciences 4- Plant Sciences 5- Hydrospheric sciences 6- global remote sensing  History and Scope of Remote Sensing A picture is worth a thousand words. It convey information about (positions, sizes, and interrelationships between objects). e.g. Your personal pictures, what is the concept of taking a photo for you ? easily can identify the main concept as “gathering of information at a distance” however, this is a broad definition ! Need to refine it. Remote Sensing discussed here is related to observations of: Earth’s land and water surfaces By means of reflected or emitted electromagnetic energy. using an instruments that present information in an image format.  In 1960-1970, first use of term “remote sensing” Many definitions of remote sensing have been published since that time. For our purposes, Remote Sensing is “the practice of deriving information about the earth’s land and water surfaces using images acquired from an overhead perspective, using electromagnetic radiation, reflected or emitted from the earth’s surface”. Remote Sensing Course- Lec. 1 Lecture will focuses on : 1- History and scope of remote sensing definitions overview of remote sensing process key concepts of remote sensing 2- Electromagnetic radiation the electromagnetic spectrum radiation laws Interactions with the atmosphere three models for remote sensing  Remote sensing and its elements Remote sensing is the technique of obtaining information about an area or object through analysis of data acquired by a device that is not in contact with the area or object. It is related to observations of: Earth’s land and water surfaces By means of reflected or emitted electromagnetic energy. using an instruments that present information in an image format. Remote Sensing Process Physical Objects Sensor data Extracted Information Application s Land Hydrolog vegetati Soils use y Geolog on y Elements of remote sensing  Elements of remote sensing (A) Source of energy The energy source that illuminate or provides electromagnetic energy to the target of interest. (B) Propagation through the atmosphere The energy will come in contact and interact with the atmosphere when travels from its source to the target and vies versa. (C) Earth surface features The energy interacts with the target, once the energy makes its way to the target through the atmosphere. (D) Retransmission through the atmosphere (energy recording by the sensor) The implemented sensor recorded emitted/scattered energy from the target.  Elements of remote sensing (E) Sensing systems Receiving and processing station where the data is converted into an image. (f) Sensing products An image produced either hardcopy or digital. (G) Interpretation and analysis Processed image is interpreted, visually or digitally to extract information about the objects. (h) Information product Expressed by digital images, extracted maps and models. (i)Users People /scientists who used the information  Key concepts of remote sensing Remote sensing concepts address ideas regards to the practice of remote sensing regardless of specific application. 1- Spectral Differentiation It is describes the differences of observed spectral in the energy reflected or emitted from features of interest. (we look for the differences in the “colours” of objects. It is the basis of Multispectral remote sensing which is defined as “The science of observing features at varied Key concepts of remote sensing 2- Radiometric Differentiation It is detects the differences in the brightness of objects and features. Term contrast related to the differences in brightness. Remote sensing instrument must be capable of recording the contrast in brightness before information derivation from the image. The existing contrast in the scene between objects and their backgrounds are a significant issue in remote sensing Key concepts of remote sensing 3- Spatial Differentiation It is describes the size of the smallest area that can be recorded by remote sensing sensor. The minimum area determines the spatial detail (the fineness of the patterns on the image). These smallest areal units are known as picture element “Pixels” Pixels could be discrete and distinct for many remote sensing system, and could be on another hand less obvious. The ability to record spatial detail is influenced  Key concepts of remote sensing 4- Geometric Transformation A specific geometric relationship represents a landscape or features in every remote sensing image. geometric relationship determined by the: 1- design of the remote sensing instrument, 2- specific operating conditions, and 3- terrain relief. The ideal remote sensing instrument would be able to provide an accurate geometric relationship between points on the ground and their corresponding representation on the image.  Key concepts of remote sensing In reality, each satellite image includes: 1- positional error caused by the perspective of the sensor optics, 2- the motion of scanning optics, 3- terrain relief 4- earth curvature These kind of errors can vary in significance, but are the resultant of the geometric errors. it is possible to remove or reduce locational error, but it must be taken into account before using images as it is the basis for measurements and distances.  Key concepts of remote sensing 5- Interchange ability of pictorial and digital formats “Pictorial and digital” are the two forms of remote sensing data, that represent different methods of display. The digital form is conducted by systematically subdividing the image into pixels (tiny areas of equal size and shape). Each pixel represented by a discrete value of the brightness. while, digital images can be displayed as pictorial images by displaying each digital value as brightness level scaled to the magnitude of the value. Remote Sensing Course- Lec. 2 Lecture will focuses on : 1- History and scope of remote sensing key concepts of remote sensing 2- Electromagnetic radiation the electromagnetic spectrum radiation laws Interactions with the atmosphere three models for remote sensing  Electromagnetic Radiation Interpretation of remote sensing imagery depends on understanding of : electromagnetic radiation, and its interaction with surfaces and atmosphere. Visible light is the most familiar form of the electromagnetic radiation, it forms a very small portion of the full radiation. But it is a very important part. Electromagnetic radiation propagate through the atmosphere in the form of sine wave. It consists of an electrical (E) and magnetic (M) filed, Electromagnetic Propagation Directi on  Electromagnetic Properties Electromagnetic energy has three properties: 1- wavelength: the distance from one wave crest to the next. 2- Frequency: a number of crests passing a fixed point in a given period of time. 3- Amplitude: the height of each peak.  Electromagnetic Properties High Low frequency frequency Short Long wavelength wavelength the shorter the wavelength, the higher the frequency. conversely, the longer the wavelength, the lower the frequency. Wavelength and Frequency define the speed (c) of the electromagnetic energy through the following relationship: Electromagnetic Regions * See Table (2.3), page 28 in your notes, you will find the wavelength limits of the EM regions.  Remote Sensing Electromagnetic Regions Three main regions of EM spectrum normally using for remote sensing operations: 1- the visible spectrum has obvious significance in remote sensing. ranges of the visible spectrum are defined by the sensitivity of the human visual system. Visible light divided into three segments: (0.4-0.5 μm) blue (0.5-0.6μm)green (0.6-0.7μm) red  The visible spectrum The color of an object is defined by the color of light that it reflects, (see Figure 2.4; page 29 in your lecture’s notes) Primary color define as a single color that can not be formed from a mixture of the other two. a “blue” object is “blue” because it reflects blue light And the same for the other two colors (green and red). complete reflection of the visible spectrum (equal proportions of the three primary colors) , produce white color.  2- The Infrared spectrum the infrared region is designated by the wavelengths longer than the red portion of the visible light. this regions extents from 0.72 to 15 μm it is wider than the visible light by 40 times, it has varied properties.  The Infrared spectrum Infrared spectrum divided into two categories: 1-near-infrared and mid-infrared radiation behaves with respect to optical systems. it is a solar radiation reflected from the earth’s surface. films, filters and cameras that use with the visible light, can be use in the near-infrared region. 2- far-infrared consists wavelengths beyond the visible light, and extending into regions that border the microwave region. it is a solar radiation that emitted by the earth’s surface.  3- The Microwave Spectrum It is : the longest wavelength commonly used in remote sensing. range from 1 mm to 1 m wavelength. merge into the radio wavelength used for broadcasting purposes. consists from several bands : (P-band, L-band, S-band, C-band, X-band); has different purposes depending on its wavelength. Remote Sensing Course- Lec. 3 Lecture will focuses on : 1- History and scope of remote sensing key concepts of remote sensing 2- Electromagnetic radiation the electromagnetic spectrum radiation laws Interactions with the atmosphere three models for remote sensing  Radiation Law The propagation of electromagnetic energy follows certain physical laws. Isaac Newton was the first one who recognise the dual nature of light. He maintained that light is a stream of minuscule particles “corpuscles” that travel in straight line. the modern theories of Planck and Einstein discovered that : “electromagnetic energy is absorbed and emitted in discrete units called Photons”  Radiation Law The size of each unit is directly proportional to the frequency of the energy’s radiation. Plank defined a relationship between frequency (v) and radiant energy (Q) as below: Q = h.v Where, h is a constant = (6.626 X 10-34 m2 Kg / s) Radiant flux (Фe) is the rate at which photons strike a surface, it specifies energy delivered to a surface in a unit of time. Measured in Watts. Radiant exitance (Me) defines the rate at which radiation is emitted from a unit area. Measured in Watts per square meter.  Radiation Law when the temperature of objects > zero, then objects have: 1- temperature, and 2- emit energy the amount of energy and the wavelengths at which it is emitted depends on: (the temperature of object) when temperature increase, the emitted energy increase and the wavelength of emission becomes shorter. Blackbody and Whitebody concept can explain the relationships between (temperature variation,  Blackbody and Whitebody blackbodies and whitebodies are Hypothetical concepts. they are behave in an idealised manner. A blackbody absorbs all incident radiation and non is reflected. so, it emits all energy with perfect efficiency; its a perfect radiator. The emitted radiation scientifically known as “emissivity (ε)” Kirchhoff’s law states that: at the same  Blackbody and Whitebody Kirchhoff’s law forms the basis for the definition of emissivity (ε) which is : “the ratio between the emittance of a given object (M) and that of a blackbody (Mb) at the same temperature”. the emissivity of a true blackbody= 1 A whitebody reflects all incident radiation and non is absorbed. so, it is a perfect reflectors; and its emissivity  Blackbody and Whitebody in nature, all objects have emissivities that fall between 0 and 1 those objects called thus (greybodies). in those objects emissivity is a useful measure of their effectiveness as radiators of EM. objects that have high emissivities, means absorb high proportions of radiation, and vies versa. The relationship between the total emitted radiation (W) and temperature (T) is defined by Stefan- Boltzmann law:  Blackbody and Whitebody Wien’s displacement law explains the relationship between wavelength (λ) of emitted radiation and the absolute temperature (T) of blackbody: When blackbodies become hotter, the wavelength of maximum emittance shifts to shorter wavelengths ( see figure 2.5 in your notes which shows the radiation curves of the blackbody). Remote Sensing Course- Lec. 4 Lecture will focuses on : 1- Radiation Interactions with the Atmosphere Scattering and its effects in remote sensing Refraction Absorption 2- radiation Interactions with Surfaces reflection Transmission 3- Spectral Properties of Objects  Interactions with the Atmosphere All radiation used for remote sensing must pass through the earth’s atmosphere. Effects of atmosphere could be negligible if the sensor is carried by a low-flying aircraft. On the other hand, atmospheric effects will have a substantial impact on the quality of remotely sensed image, because the EM energy passes through the entire depth of the earth’s atmosphere. Therefore, understanding the interactions of the EM with atmosphere is extremely required for the future analysis of remote sensing image.  Interactions with the Atmosphere Interactions of the energy with the atmosphere translated by several physical processes, including: (1)Scattering is the redirection of EM energy by particles suspended in the atmosphere or by large molecules of atmospheric gases. in other words, a portion of the incoming solar beam is directed back toward space and toward the earth’s surface. Scattering amount depends upon: the sizes of atmospheric particles their abundance the wavelength of the radiation the depth of the atmosphere through which the  Interactions with the Atmosphere/ Scattering Rayleigh scattering is the common form of scattering, as it is discovered by British scientist J. Rayleigh. He demonstrated that “ a perfectly clean atmosphere, consisting only of atmospheric gases, causes scattering of light in a manner that the amount of scattering increases greatly as wavelength becomes shorter”. in other words, Rayleigh scattering occurs when atmospheric particles have diameters that are very small relative to the wavelength of the radiation. Rayleigh scattering referred some times as “clear  Interactions with the Atmosphere/ Scattering Rayleigh scattering is the dominant scattering process high in the atmosphere, up to altitudes of 9 to 10 km. Rayleigh scattering applies only to a specific class of atmospheric interactions, although it forms an important understanding of the atmospheric effects on transmission in the visible spectrum. thus, another scattering theory has been published by a German physicist Gustave Mie, that describes atmospheric scattering caused by large atmospheric particles , including: dust, pollen, smoke and water droplets.  Interactions with the Atmosphere/ Scattering Mie scattering tends to be greatest in the lower atmosphere (0 to 5 km), where larger particles are abundant. another form of scattering is known as “Non- selective scattering” which is caused by particles that are much larger than the wavelength of the scattered radiation. such particles might be larger water droplets or large particles of airborne dust. Non-selective scattering is not wavelength- dependent, so such a scattering observes as a whitish or grayish haze.  Interactions with the Atmosphere/ Scattering Effects of scattering in remote sensing scattering causes the atmosphere to have a brightness of its own. for remote sensing, scattering has an important consequences , such as the radiation in the blue and ultraviolet region of the spectrum is usually not considered useful for remote sensing. WHY ? because of the wavelength dependency of Rayleigh scattering, that means blue and ultraviolet regions are the most strongly affected by scattering, thus image that record these portions of the spectrum  Interactions with the Atmosphere/ Scattering for this reason, remote sensing instruments often exclude short-wave radiation by using a kind of filters. furthermore, scattering tends to make dark objects appear brighter than they would otherwise be and the bright objects appear darker. So, it is decreasing the contrast recorded by the sensor. In other words, “scattering degrades the quality of satellite image”. if you see to figure (2.8) in your notes, some of the above effects illustrated. It could be concluded that the observed radiance by the sensor (I) is the sum of : I = IS + IO +ID  Interactions with the Atmosphere/ Scattering Where, Is represent radiance reflected from the earth’s surface. IO represent radiation scattered from the solar beam directly to the sensor without reaching the earth’s surface ID represent diffusion radiation, directed first to the ground and then to the atmosphere. the value of IS varies with differing surface features or materials, topographic slops and orientation. the value of IO is often assumed to be more or less constant over large areas.  Interactions with the Atmosphere/ Refraction (2) Refraction Is defined as the bending of light rays at the contact area between two media that transmit light. Refraction occurs in the atmosphere as light passes through atmosphere layers of varied clarity, humidity and temperature. these variation influence the density of atmospheric layers, which in turn causes a bending of light rays as they pass from one layer to another. The ratio between the velocity of light in a vacuum (c) to its velocity in the medium (cn) represent the “Index of Refractions”  Interactions with the Atmosphere/ Refraction In the case that assuming uniform media, as the light passes into a denser medium, it is deflected toward the “surface normal” which is a line perpendicular to the surface at the point when the light ray enters the denser medium. (see figure 2.10 in your notes) in that figure it could be seen that the angle θ’ defines the path of the refracted ray, and is given by Snell’s law: n sin θ = n’ sin θ’ Where, n and n’ are the indices of refraction of the first and second media respectively. While θ and θ’ Interactions with the Atmosphere/ Absorption (3) Absorption It is occurs when the atmosphere prevents, or strongly attenuates, transmission of radiation or its energy through the atmosphere. Three gases are responsible for most absorption of solar radiation: 1- Ozone (O3) is formed by the interaction of high-energy ultraviolet radiation with Oxygen molecules (O2) high in the atmosphere. although naturally occurring concentrations of Ozone are quite low, Ozone plays an important role in the earth’s energy balance.  Interactions with the Atmosphere/ Absorption 2- Carbon dioxide (CO2) also occur in low concentration , mainly in the lower atmosphere. it is important in remote sensing, because it is effective in absorbing radiation in the mid and far infrared region of the spectrum. Its strongest absorption occurs in the region from about 13 to 17.5 mm (in the mid infrared) 3- water vapour(H2O) it is commonly present in the lower atmosphere (below about 100 km) the role of atmospheric water vapour varies greatly with time and location. the water vapour is several times more effective in absorbing radiation than are all the other atmospheric Remote Sensing Course- Lec. 5 Lecture will focuses on : 1- Atmospheric windows 2- radiation Interactions with Surfaces reflection Transmission Absorption 3- Models for remote Sensing  Atmospheric Windows The atmospheric gases form an important barriers to transmission of EM radiation through the atmosphere. thus, atmosphere selectively transmits energy of certain wavelength, Those wavelength that are easily transmitted through the atmosphere are referred to as “ Atmospheric Windows”. (see figure 2.11 in your notes) Positions, extents and effectiveness of atmospheric windows are determined by the absorption spectra of atmospheric gases. Atmospheric Windows  Atmospheric Windows Only the wavelength regions “outside” the main absorption bands of the atmospheric gases can be used for remote sensing. Energy at other wavelengths, not within the windows, is severely attenuated by the atmosphere, and therefore cannot be effective for remote sensing. in the visible and far infrared region, the two most important windows extend from 3.5 to 4.1 µm, and from 10.5 to 12.5µm respectively. a few of the most important atmospheric windows are listed in table (2.4) in your notes.  Interactions with Surfaces Energy that reaches to the earth’s surface will interact with earth’s surface. interaction takes three forms: 1- reflection 2- absorption 3- transmission the proportion of each process depend upon: (1)The nature of the surface, (2) the wavelength of the energy and (3) the angle of the illumination.  Interactions with Surfaces/ Reflection It is occurs when a ray of light redirected as it strike a non-transparent surface. the nature of the reflection depends upon sizes of surface irregularities (roughness or smoothness), in relation to the wavelength of the radiation considered. so, according to that, there are two types of reflection: 1- Specular reflection occurs when the surface is smooth all or almost all of the incident radiation redirects in  Interactions with Surfaces/ Reflection for such surfaces, the angle of incidence is equal to the angle of reflection for visible radiation, specular reflectance occurs with surfaces such as a mirror, water surface, smooth metal.  Interactions with Surfaces/ Reflection 2- Diffuse reflection occurs when the surface is rough energy is scattered more or less equally in all directions. (see figure 2.14b in your notes) for visible radiation, many natural surfaces behave as diffuse reflectors, such as: uniform grassy surfaces  Interactions with Surfaces/ Transmission occurs when radiation passes through a substance without significant attenuation. the ability of medium to transmit energy is depend on a (given thickness or depth of a substance) this ability is defined as “transmittance” (t) which is defined by the following formula: t= transmitted radiation / incident radiation in respect to the materials naturally occurs , water bodies, plants and soil could be capable of transmitting significant amounts of radiation.  Interactions with Surfaces/ Transmission However, transmittance of many materials varies greatly with wavelengths, for example, Plant leaves are generally opaque to visible radiation, but transmit significant amounts of radiation in the infrared spectrum.  Models for Remote Sensing Remote sensing typically takes one of three basic forms depending on: the wavelengths of energy detected , and the purpose of the study 1-the first model is representing the simplest form which is “recording the reflection of solar radiation from the earth’s surface”.(see figure 2.20 in your notes) 2- A second model is “recording radiation emitted from the earth’s surface”. (see figure 2.21 in your notes) emitted radiation reveals information concerning thermal properties of materials which in turn can be  Models for Remote Sensing This model also represent “passive” remote sensing, because it employs instruments designed to sense energy emitted by the earth. 3- A Third model is “generate their own energy using special designed sensor”. (see figure 2.22 in your notes) then, record the reflection of that energy from earth’s surface, so this model represent “active” remote sensing. In practice, active sensors are best represented by “imaging radar and Lidar”