Course
Understanding Earth Observation:
Electromagnetic Foundations of Remote Sensing
Domenico Solimini
Starting November 2011
Rationale
The quite large distance between the mathematical description of electromagnetic waves and the user applications of Earth observation is one reason of the generally partial and fragmented comprehension of the information content of remote sensing data.
Overlooking a thorough and global understanding of how the remote information is produced and transfered may result in slow and hampered development of processing tools, in inefficient retrieval schemes, in non-optimal choices and decisions, in occasional pitfalls.
The course attempts to provide a comprehensive overview of the interaction between electromagnetic waves and the terrestrial environment, aiming at highlighting the information contained in the remote data for different frequency bands. The end-to-end path from basic electromagnetics up to image and data features is scanned. Numerical problems are proposed and case studies are discussed to deepen the comprehension process.
Content
The electromagnetic field: Maxwell’s equations, electromagnetic parameters of materials, boundary conditions, energy budget, time-harmonic representation, vector polarization; quasi-monochromatic fields, polarization matrix, temporal and spatial coherence.
Electromagnetic parameters: permittivity in the frequency domain for tenuous or polar materials, conductivity and its relation with permittivity; microwave and optical/IR dielectric properties of atmosphere, water, acqueous dielectrics, vegetation, soil, ionosphere.
Coherent wave propagation: electromagnetic field in the geometrical optics approximation, wave propagation in weakly inhomogeneous media, electromagnetic rays, electromagnetic path length, rays in plane and radial media, rays in the troposphere, weakly lossy inhomogeneous media, attenuation.
Plane waves: electromagnetic field in homogeneous media, phase and attenuation vectors, atmospheric transmissivity, intrinsic impedance, Jones and Stokes field representation, Poincaré sphere..
Wave reflection and refraction: normal and oblique incidence, effect of polarization, Brewster angle, reflection from a slab, dielectric vs. lossy materials, total reflection.
Electromagnetic radiation: Green’s function for free space, field of point source, finite sources, far field, electromagnetic reciprocity, equivalence.
Antennas and apertures: field and power radiation patterns, gain, effective area, aperture efficiency, receiving co- and cross-polarizations; linear antennas; rectangular, circular, elliptical apertures; main and secondary lobes, beamwidth.
Electromagnetic scattering: scattering function, scattering and Mueller matrices; scattering, absorption and extinction transverse sections, albedo; the radar equation; extended targets and spatial resolution; properties of scattering, coherent vs. incoherent scattering; large and small scatterers; bodies with planar and with rough interfaces; scattering from bodies with random permittivity.
3-D positioning in Earth observation: spatial resolution and positioning in passive and active systems; real and synthetic antennas; effects of slope, lay-over, double bounce in radar images;
retrieval of height information; SAR interferometry, de-ranging, unwrapping; accuracy of interferometric measurements; effect of the atmosphere, electromagnetic path length, single- vs. repeat-pass interferometry; labile vs. stable scattering; interferometric coherence; differential interferometry.
Electromagnetic spectrum and information: the electromagnetic spectrum in Earth observation; effect of the atmosphere; frequency-dependent interaction mechanisms and sensed environmental parameters; passive and active techniques from visible to microwaves.
Interaction of electromagnetic waves with the earth surface: reflection, scattering and emission from the earth; surface and volume scattering; effects of bio-geo-physical parameters; reflection, scattering and emission features of environmental materials in the visible, near and thermal infrared and microwaves; information on terrain, vegetation, sea, snow and ice.
Radiative transfer: wave propagation in an absorbing and scattering medium; radiative transfer equation, formal solution; radiative transfer at microwaves; ground-based and satellite-based radiometric observations from visible to microwaves.
Appendix: recalling vectors and coordinate systems, recalling operators, gradient, divergence, curl, recalling curvilinear coordinates, operators in orthogonal curvilinear coordinates, recalling nabla and its use, Laplacian.
Schedule and venue
Lectures
UEO consists of two parts, basic and advanced.
Classes of the basic course will be on Tuesdays at 16:00, classes of the advanced course on Thursdays at 16:00. GeoInformation seminars or other events might occasionally cause changes.
An introductory plenary meeting will be on Thursday 17 November 2011 at 16:00, to discuss the contents and to refine the organization.
Venue
Meeting room of the Department of Computer, Systems and Production Engineering – DISP – located on the ground floor of the “Ingegneria della Informazione” A-building, Via del Politecnico, 1.
Admission
The course is intended for the GeoInformation PhD candidates.
It will be open also to interested personnel of the institutions that support or have supported the GeoInformation PhD Program.
Given the limited capacity of the room, admission will be on a first arrive first served basis.
GeoInformation PhD candidates are automatically enrolled. Other persons planning to attend the courses are kindly requested to send an e-mail to Dr. Daniela Picin (picin@disp.uniroma2.it).
Recent Comments