Remote sensing for resources development and environmental management: Remote sensing for resources development and environmental management

Damen, M. C. J.

Bibliographic data

Multivolume work

Persistent identifier:: 856342815

Title:: Remote sensing for resources development and environmental management

Sub title:: proceedings of the 7th international Symposium, Enschede, 25 - 29 August 1986

Year of publication:: 1986

Place of publication:: Rotterdam; Boston

Publisher of the original:: A. A. Balkema

Identifier (digital):: 856342815

Language:: English

Additional Notes:: Volume 1-3 erschienen von 1986-1988

Editor:: Damen, M. C. J.

Document type:: Multivolume work

Volume

Persistent identifier:: 856343064

Title:: Remote sensing for resources development and environmental management

Sub title:: proceedings of the 7th international Symposium, Enschede, 25 - 29 August 1986

Scope:: XV, 547 Seiten

Year of publication:: 1986

Place of publication:: Rotterdam; Boston

Publisher of the original:: A. A. Balkema

Identifier (digital):: 856343064

Illustration:: Illustrationen, Diagramme

Signature of the source:: ZS 312(26,7,1)

Language:: English

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

Editor:: Damen, M. C. J.

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:: 2 Microwave data. Chairman: N. Lannelongue, Liaison: L. Krul

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: Shuttle imaging radar response from sand dunes and subsurface rocks of Alashan Plateau in north-central China. Guo Huadong, G. G. Schaber & C. S. Breed, A. J. Lewis

Document type:: Multivolume work

Structure type:: Chapter

137 Symposium on Remote Sensing for Resources Development and Environmental Management / Enschede / August 1986 Shuttle imaging radar response from sand dunes and subsurface rocks of Alashan Plateau in north-central China Guo Huadong Institute of Remote Sensing Application, Academia Sinica, Beijing, China G.G.Schaber & C.S.Breed US Geological Survey, Flagstaff, Ariz., USA A.J.Lewis ERSAL, Oregon State University, Corvallis, USA ABSTRACT: SIR-A and SIR-B images of three sand dunes and two bedrock regions in alashan Pla teau of north-central China have been studied and compared to Landsat imagery and field in vestigation data. The results of the study show that radar illumination direction is an im portant factor which results in the echo strength change for the same type and size of sand dunes. The sand dunes in which the slipfaces are oriented to radar beam have a bright-point response and the dunes in which the gentle slopes face the radar beam have a dark signature on the radar image. Two Precarnbrian metamorphic rock bodies buried beneath the thin layer of alluvial material or aeolian sand have been detected by using these two radar images. 1 INTRODUCTION The Shuttle Imaging Radar-A and B (SIR-A and SIR-B) carried on the Space Shuttle Columbia in November 1981 and the Challenger in Octo ber 1984 acquired images of part of Alashan Plateau in north-central China. This very dry plateau covers three deserts of the main thirteen ones over the country. One of these deserts, the Badain Jaran, contains some of the tallest dunes in the world. These SIR-A and SIR-B images are the only orbital radar data acquired over China and provide a great deal of information on these sand dunes as well as subsurface geological features. In this paper five areas are stu died, including three ounes anu two aeolian sand and bedrock regions (Fig.1). The pur pose of this study is to understand the L- band radar responses from sand dunes and some subsurface features. One of the authors (Guo Huadong) conducted field work in several study areas covered by radar imagery. The Landsat images compared with the radar data were optimally processed on the VAX 11/750 computer system of the U.S. Geological Survey in Flagstaff, Arizona. Fig. 1 Index and simplified geologic map of the Alashan Plateau showing location of the five study areas.I--Yamalik Dunes; II--Yapulaishan area; III—Badain Jaran Desert; IV—Shuangjinzhi study area; V--Aertengaobao study area. R--Bedrock N--Neogene Q--Quaternary 2 COMPUTER ENHANCEMENT TO THE SIR-a AND MSS IMaGES SIR-A is a L-band synthetic aperture radar with HH polarization and is imaged witn op tical recording method. The radar on ooard recieves the information on phase and ampli tude of the echo from the ground target, which represents the change of the scatterring strength. The information is recorded on the data film and then processed with optical relative processor to form image film. The SIR-A image is processed with digital enhancement technique in order to study the radar scatterring characteristics from the desert region more effectively; the Landsat MSS CCT data is also processed with the same technique to be used as the data for matching analysis. In this study, the radar image covering the test region is digitized to form an image matrix consisting of 2439 by 46OO pixels. The high pass filtering technique is considered to be an important one in the pro cessing of SIR-A data because it has the same defect with other on-board radar images, that is, there are too many speckles on the image, which are easily confused with speckle-shaped echoes from the dunes. The speckle noise may be lowered by filtering the image. A selection of the filtering window is im portant to the processing. The window of 101 by 101 has been accepted a traditional one in the filtering process for the MSS data. But there is no such an optimum window for the space radar image in this dune area. So, four windows, 3 by 3, 5 by 5, 23 by 25 and 101 by 101 are chosen respectively. Anotner kind of filtering, the divided filtering, is also used. The back scatterring strength of radar changes sharply with different back ground formed by different ground objects. Due to the higher dielectric constant as well as the effect of corner reflector , the ob jects such as bedrock, vegetation and buil ding usually have stronger echoes; and the echoes from the objects such as smootn ground, water body and dry sand are much weaker. The obvious difference between the DN values of these two types of objects makes a high con trast on the image. This is, of course, an unfavourable factor to image interpretation. The principle of the divided filtering is to divide the original data by its low pass

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