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

Damen, M. C. J.

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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

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Structure type:: Chapter

Chapter

Title:: Oil drums as resolution targets for quality control of radar survey data. B. N. Koopmans

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Structure type:: Chapter

)0K DIRECTION 7 8 9 * \ / 7~7—r-?- r -r~r-? / / LOUGHED STRIP 1 2 grass surface >rs in the er barbed wire ew metres wide iivide. Farther s grass cover, on on 23 June lar in X and C over the test rocessed (high obtained over able in X- and 2° towards the only in C-band and during the respectively, if drum reflec- ght patches by film has been 3x enlargement :he transparen- lears as a dark s could be ex- ction. On both as occur repre shallow depres- his is followed (urface texture, which separates ivide. The fire s of the rough- OK DIRECTION 3 LOUGHED STRIP '—' 1 2(?) ilectors on tted) ness of the ploughed bare soil surface. The back ground tone of the grass field surrounding the drum reflectors is uniform and relatively dark as a result of the low scattering. On the radar strip 77 C-band, most drum reflec tors can be differentiated under the microscope, as shown in fig. 3. Their size and separation were measured with a micrometer. Drum reflectors 1 and 2 are 4 m apart and can be seen as two different point targets. The same is true for 2 and 3. Target points 3 and 4 are separa ted only 2 m in the field but appear on the image as two separate targets roughly 3 to 4 m apart, whereas drum reflectors 4 and 5, which are also 2 m apart, are hardly separable on the image. All five targets have the same orientation, horizontal, and not inclined towards the incoming radar beam. There is no indication for the reason why the first two targets gave less backscatter than the third one. Drum reflectors 6 and 7 are only 1.5 m apart and could not be seen as separate targets, but appear as one large blob. Reflectors 8 and 9, on the other hand, which are 2 m apart, can be seen as two dif ferent targets. Reflectors 10 and 11 also gave high returns, but 12 is not discernible. The approximate 2 m azimuth resolution for these targets confirms the data given by Intertech. Fig. 4 Radar response drum-reflector field as seen under a 63X microscopic enlargement (3rd generation optically correlated imagery): a. Strip 78X under 32° depression angle b. " 77C " 42° c. " 76C " 70° Strip 76 C-band gives a distribution of point targets as sketched in fig. 4c. Most of the drum reflectors seem to be present in the image under the microscope and their site and separation is more or less according to scale. The alignment of the drums, however, is absent, and the image seems to suffer some distortion. On strip 78 X-band, the drums are not well defined point targets, but appear to be smeared out in range direction over distances of approximately 10 m. This seems to occur over the entire image. In azimuth directions, a number of the aligned point targets can be separated, although it is difficult to assign numbers to the blobs (fig. 4a). Of reflectors 1-5, at least 4 seem to be present and separable, and of 6-9, at least 2. This agrees wit an azimuth separation of about 2 metres. The range resolution, however, is far less for the X- band (about 10 m) than for the C-band (about 2m). As no more X-band images are available over the site, no conclusion is warranted if range resolu tion is far below specification on all X-band images. The following is a summary of the results yielded by the four radar strips. Strip 78 X-band, depression angle 32°: Drums not well-defined point targets, range resolution ± 10 m azimuth resolution ± 2 m. Strip 78 C-band: Drums reasonably defined point targets, range resolution ± 2 m, azimuth resolution ± 2 m. Strip 77 C-band, depression angle 42°: Drums well-defined point targets, range and azimuth reso lution better than 2 m. Strip 76 C-band, depression angle 70°: Drums reasonably defined point targets, range distortion: no proper alignment, azimuth resolution ± 2 m. CONCLUSION As a conclusion, it can be stated that oil drums cut in half can be used as point targets for assessing spatial resolution. They are detectable on the radar image. Care must be taken that a uni form low-response background is present. A smooth grass or sand surface is good for this. A number of these drums, oriented with respect to radar look direction, should be placed in a recognisable con figuration so that it is possible to locate them on the radar images. Working with digital data makes quantification easier: nevertheless, optically processed data studied under high magnification can give good quantitative insight into the ground resolution and image quality of the system. Such a test site can be cheaply set-up, even in developing countries, and can serve as a test site at the beginning and end of each flight mission during a radar survey campaign. REFERENCES Forshaw, M.R., A. Haskell, P.F. Miller, D.J. Stanley and J.R. Townshend 1980. A review paper: Spatial resolution of Remotely Sensed Imagery. U.S. Committee Peaceful Uses of Outer Space, 53 pp. Intertech Remote Sensing Ltd., 1981. ESA/JRC SAR 580 campaign system specification document. Intertech report 951-81-1. Koopmans, B.N., C. Anton Pacheco, T. Woldai and A. Payas, 1985. SARTHI: A side-looking radar survey over the Iberian Pyrite Belt. Investigators final report Vol. 2. The European SAR-580 Experiment JRC/ESA publ. SA.1.04.E2.85.12/2, p. 125-149. Smith, D.J. Quality assessment of SAR-580 pro ducts. Investigators final report Vol. 1. The European SAR-580 Experiment JRC/ESA publication SA.1.04.E2.85.12/1, p. 63-69.

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