Proceedings of the Symposium on Global and Environmental Monitoring: Proceedings of the Symposium on Global and Environmental Monitoring

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Persistent identifier:: 856665355

Title:: Proceedings of the Symposium on Global and Environmental Monitoring

Sub title:: techniques and impacts ; September 17 - 21, 1990, Victoria Conference Centre, Victoria, British Columbia, Canada

Year of publication:: 1990

Place of publication:: Victoria, BC

Publisher of the original:: [Verlag nicht ermittelbar]

Identifier (digital):: 856665355

Language:: English

Document type:: Multivolume work

Volume

Persistent identifier:: 856669164

Title:: Proceedings of the Symposium on Global and Environmental Monitoring

Sub title:: techniques and impacts; September 17 - 21, 1990, Victoria Conference Centre, Victoria, British Columbia, Canada

Scope:: XIV, 912 Seiten

Year of publication:: 1990

Place of publication:: Victoria, BC

Publisher of the original:: [Verlag nicht ermittelbar]

Identifier (digital):: 856669164

Illustration:: Illustrationen, Diagramme, Karten

Signature of the source:: ZS 312(28,7,1)

Language:: English

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Editor:: International Society for Photogrammetry and Remote Sensing, Commission of Photographic and Remote Sensing Data

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Volume

Collection:: Earth sciences

Chapter

Title:: [TA-1 OPENING PLENARY SESSION]

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: GLOBAL AND ENVIRONMENTAL MONITORING: TECHNOLOGICAL CONSIDERATIONS. by John S. MacDonald, MacDonald Dettwiler, Richmond, B.C., Canada

Document type:: Multivolume work

Structure type:: Chapter

the atmosphere at (d), and finally enters the spacecraft instrument (e). It is this energy that is measured by the instrument. In summary, the quantity that we are seeking is the ratio of d to c (the reflectance - which characterizes the surface material), but the quantity measured is e (the radiance entering the instrument). Part of the processing that is undertaken must, by one means or another, derive the reflectance from the measured radiance taking into account all of the factors which have been noted above. We call this process reflectance modelling. Accurate modelling of the reflectance process is quite a complex undertaking (Woodham & Gray [1987]). The process is illustrated in Figure 4. The energy entering the instrument at point E has three components: (1) energy reflected directly from the target pixel (T), (2) energy reflected from an adjacent pixel (A) and scattered by the atmosphere, and (3) energy which is simply scattered by the atmosphere. In addition, the energy illuminating the target pixel has several components: direct illumination by the sun, light from the sun which has been scattered in the atmosphere, light which has been reflected from adjacent pixels and light which has been reflected from adjacent pixels and scattered by the atmosphere. Depending on the shape of the surface, and the relative positions of the illuminating source (the sun) and the sensor, some of the the pixels may not be directly illuminated at all because they are in the shadows of hills or mountains. These pixels are illuminated only by light which has been scattered by the atmosphere and/or reflected off adjacent pixels. All of this is in addition to the effects caused by orientation of the target pixel. It is clear that in order to model this situation adequately, a digital elevation model which describes the shape of the surface is necessary. Figure 4 Reflectance Modelling The Digital Elevation Model and its Importance The above discussion has emphasized the importance of the availability of a digital elevation model in accurately determining the reflectance of surface material. The digital elevation model is critical in other respects as well. Radar backscatter is a strong function of the orientation of the surface pixel relative to the incoming radiation. The ability to relate backscatter readings acquired

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