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

8 at different incidence angles is therefore highly dependent on knowledge of the shape of the surface. The precision location of measurements is essential if we are to be able to integrate and fuse data sets. Compensation for the relief distortion effect which arises in optical sensors viewing off-nadir, and the layover effect inherent in the geometry of synthetic aperture radar both require a priori knowledge of the shape of the underlying terrain. A digital elevation model is therefore a critical element in the construction of the measurement database. The acquisition of a DEM on a worldwide basis is therefore a high priority task. There are two technical approaches to such an undertaking: Stereo methods using optical sensors, and synthetic aperture radar interferometry. The first method has been demonstrated to yield the necessary accuracies (Kauffman and Wood, [1987], Simard, [1988] ), and the second method, though less mature, shows significant promise (Im, [1990] , Li and Goldstein [1990]. Interferometric radar has the significant advantage that it is capable of operating through cloud cover, and therefore presents the basis of a system which will be able to acquire a world-wide model in a predictable interval of time. QeQCPding The requirement for precise location of each pixel independent of the acquiring satellite implies that the data should be transformed into a standard coordinate system, as part of the geometric rectification process. The necessity to be able to relate each pixel to the topography in order to determine the reflectance model, and the general requirement that different data sets all relating to the same area of the earth's surface should be easily combinable, imply that the selected standard coordinate system should be a standard geographic projection. Satellite data geometrically corrected to a standard geographic grid is called geocoded data. One can see that if, for each data set, the position and attitude of the sensor is available together with the characteristics of the illumination source and the time of acquisition, and each pixel is calibrated and geocoded, it is possible to: (a) reconstruct the path travelled by the energy through the atmosphere, and hence derive the appropriate atmospheric corrections (assuming one has information which allows proper characterization of the atmosphere as it was at the time of data acquisition). (b) reconstruct the illumination conditions on each surface pixel (assuming the availability of a DEM). (c) combine the data set with other geographic data and with other geocoded remote sensing data sets. Geocoding the data is central to successfully accomplishing these objectives. Geocoded Data Sets Detailed treatments of the geocoding of remote sensing data are to be found elsewhere (Friedmann [1981], Guertin and Shaw [1981], MacDonald and Friedmann [1985]), hence the discussion presented here will cover only the important features of this type of data set. The basic idea behind the geocoding of a data set is to transform it from the coordinate system in which it is acquired, which is dependent on the acquisition system (satellite and sensor), into a geographic coordinate system which is linked into a standard mapping system, and therefore independent of the geometric characteristics of the spacecraft orbit etc. This concept is illustrated in Figure 5. r The figure shows the satellite scanning track running from top right to bottom left. Image data long this track is divided into segments known as scenes, and the pixels are arranged in rows perpendicular to the satellite track. This coordinate system, in the case of the LANDSAT satellite,

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