2Introduction of Remote Sensing DefinitionHistory of Remote SensingBasic components of Remote sensingElectromagnetic Remote Sensing ProcessElectromagnetic spectrumPassive and active remote sensing
3Different types of Resolution Spatial ResolutionSpectral ResolutionRadiometric ResolutionTemporal ResolutionCharacteristics of various sensorsSatellites: IRSFundamentals of Image Processing
4Component of Remote Sensing Energy Source or Illumination (A)2. Radiation and the Atmosphere (B)3. Interaction with the Target (C)4. Recording of Energy by the Sensor (D)5. Transmission, Reception, and Processing (E)6. Interpretation and Analysis (F)7. Application (G)
5Electromagnetic Radiation Two characteristics of electromagnetic Radiationwavelengthfrequency.
6The Electromagnetic Spectrum Thereare several regions of the electromagnetic spectrum which are useful for remote sensingFor most purposes, the ultraviolet or UVportion of the spectrum has the shortestwavelengths which are practical for remotesensing. This radiation is just beyond theviolet portion of the visible wavelengths,hence its name. Some Earth surfacematerials, primarily rocks and minerals,fluoresce or emit visible light when illuminatedby UV radiation.
7Ex. Assume the speed of light to be 3x108 m/s Ex. Assume the speed of light to be 3x108 m/s. If the frequency of an electromagnetic wave is 500,000 GHz (GHz =gigahertz = 109 m/s), what is the wavelength of that radiation? Express your answer in micrometres (μm).
9ProblemsEx . A given SLAR system transmits pulses over a duration of Find the range resolution of the system at a depression angle 450Ans: 21mEx. A given SLAR system has a 1.8 mrad antenna beamwidth. Determine the azimuthal resolution of the system at ranges of 6 km and 12 kmAns: 10.8 m & 21.6 mEx. A given SLAR system has a 2 mrad antenna beamwidth and wavelength of the transmitted pulse is 5 cm. Determine the length of the antennaAns: 25 m
10SLARThe deficiencies of brute force operation are overcome in synthetic aperture radar (SAR) systems.Having short physical antenna through modified data recording and processing techniques, but synthesize the effect of a very long antenna.The result of this mode of operation is a narrow effective antenna beamwidth, even at far ranges, without requiring physically long antenna or a short operating wavelength.At the detailed level, the operation of SAR systems is quite complexThis concept shown in Figure
11Fig. Concept of an array of real antenna positions forming a synthetic aperture
13Operate on the principle of using the sensor motion along track to transform a single physically short antenna into an array of such antennas that can be linked together mathematically as part the data recording and processing proceduresThe "real" antenna is shown in several successivepositions along the flight line.These successive positions are treated mathematically as if they are simply successive elements of a single long synthetic antenna
14Fig. Variation of spatial resolution of a) SLARb) SAR