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:: 856641294

Title:: Remote sensing for resources development and environmental management

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

Scope:: IX Seiten, Seiten 551-956

Year of publication:: 1986

Place of publication:: Rotterdam; Boston

Publisher of the original:: A,. A. Balkema

Identifier (digital):: 856641294

Illustration:: Illustrationen, Diagramme

Signature of the source:: ZS 312(26,7,2)

Language:: English

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

Editor:: Damen, M. C. J.

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:: 5 Non-renewable resources: Geology, geomorphology and engineering projects. Chairman: J. V. Taranik, Liaison: B. N. Koopmans

Write comment:: Wegen zu enger Bindung kommt es teilweise im Original zu Textverlust.

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: Application of stereo-terrestrial photogrammetric technique to varied geoscientific investigations. N. K. Agarwal

Document type:: Multivolume work

Structure type:: Chapter

of photogrammetry : 837), on suitable faces of either rock outcrops, hut or tree serve best as the control points. These,besides being very convenient to establisn in the field, also provide accuracy and consistency during model orientation in the stereo-plotter. The ground survey of these permanent control points can be undertaken independent of photography. Further, in case a fresh photography of the area becomes necessary, repeat survey of such control points is not required. If the area to be surveyed does not have suita bly located objects for establishing permanent control points, then temporary control points need to be established. A white painted round ball fixed on the mounting rod of the reflector of the Distomat (Fig.l) forms a suitable temporary control point. An advantage with such an arrange ment is that the photography and the survey of control point can be done simultaneously. Even a temporary control point should be located, to the extent possible, over some fixed object with a centering mark, so that if repeat photography becomes necessary, the temporary control point can be placed at the same location, thereby avoid ing a fresh ground survey. In case the area to be mapped falls in more than one stereo-pair then it is required to have at least two control points common in adjoining stereo-pairs. The above described temporary control point, being round in shape is equidimensional and if located at vantage open places would be visible from different places and hence would form an ideal tie point. 2.2 Photographic Camera Choice In course of photography it has been noted that in some cases a camera of 200 mm focal length would have been appropriate in place of the availa ble Camera of 100 mm focal length. Since on account of topographic restrictions in field, the camera stations had to be located at a farther distance than required. As a result the intended area was covered only in a part of the photoframe. In such cases if a larger focal length Camera is used then the required area would be covered in full photoframe, providing a larger scale photography, which in turn would result in higher resolution and greater accuracy. Therefore, it is desirable that the photographic unit contains Cameras of different focal lengths so that depending upon the available locations for photography, the appro priate camera may be used. Since the orientation system remains the same for these Cameras, only one oreintation system is sufficient for the unit. In most of the cases only one Camera was used for photography. The stereo-pairs were obtained from two Camera stations by interchanging the position of the target and the Camera. However, in case of glacier surveys two Cameras were used for obtaining the stereo-pairs at the same instant of time, since on glaciers the weather conditions fluctuate rather rapidly. Unmounting, packing and shifting of the Camera from one station to the other, through rugged glaciated terrain, and resetting it at the second station involves good amount of time resulting in variations in photogra phic conditions. However, it was noted that orientation of model on the stereo-plotter was much easier and rela tively more accurate when only one Camera was used for the photography. It was perhaps due to the fact that the elements of inner orientation remain same when only one Camera is used. 2.3 Photographic prints in field It is desirable to get photographic prints of C Figure 1. Temporary control point (a), fixed on mounting rod (b), of reflector prism (c) the stereo-pair in the field itself so that control points are properly identified and numbered to avoid any confusion during model orientation in the laboratory. Further stereo-pairs can be inter preted in the area itself supported by field checks and collection of ground truth data. Thus revisit to the area for the purpose can be avoided. For photo-interpretation in field a pocket mirror-ste reoscope has been found to be very convenient and handy. In remote, inaccessible areas it is not possible to have the facility of a photolab, therefore, an improvised, handy photo-printing technique was adopted. The standard ready-made re-agents were used for the photographic work. Developing of negatives is a simpler work, but the main pro blem comes in making prints which require a contro lled diffused light source. For making prints the photographic paper and the negative were placed between two ground glass plates, it was exposed by a light source from a three cell torch whose transparent glass was replaced by a ground glass. After one or two trials it became possible to get sufficiently good quality prints. Duplicate exposures of each area was obtained, one for deve loping in the field and the other for processing in the laboratory. The main consideration for applying terrestrial photogrammetric technique for the selected case studies has been the constraints inherent in conven tional survey techniques for accurate mapping of such areas. Besides, the technique has distinct advantages of speed, economy and precision over conventional survey techniques. 3.1 Escarpment slope mapping of Supa dam A concrete dam was under construction across a 552 3. SELECTED CASE STUDIES ■■■■■■■

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