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:: 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:: Use of (stereo-) orthophotography prepared from aerial and terrestrial photographs for engineering geological maps and plans. Niek Rengers

Document type:: Multivolume work

Structure type:: Chapter

Symposium on Remote Sensing for Resources Development and Environmental Management / Enschede / August 1986 665 Use of (stereo-) orthophotography prepared from aerial and terrestrial photographs for engineering geological maps and plans Niek Rengers International Institute for Aerospace Survey and Earth Sciences (ITC), Enschede, Netherlands ABSTRACT: Orthophotography, prepared by optical mechanical correction of aerial or terrestrial photography, is imagery with a uniform scale and without relief displcement. Together with so called "stereomates", pre pared from overlapping imagery, stereovision can be obtained. Examples of stereo-orthophotography are shown with their engineering geological interpretation. A comparison is made of the interpretability of stereo orthophotography at various scales as compared with normal stereo photography for various terrain details which are used for delineation of engineering soil and rock units as well as for slope instability pheno mena. ORTHOPHOTOGRAPHY Stereo aerial photography and stereo terrestrial photography are important tools for the engineering geologist. Interpretation of the stereo imagery under the mirror stereoscope is very helpful during the early stages of preparation of an engineering geological map or plan for a civil engineering pro ject (IAEG, 1981). One of the main problems encountered when using photography is that due to the central projection the image shows important variations in scale and radial relief displacements when the terrain is not completely flat. Thus the transfer of information from a photo overlay to a topographical map (a ver tical parallel projection of the terrain on the horizontal datum plane) causes a large amount of extra work and an important source of errors. Orthophotography offers an elegant way out of these problems. An orthophotograph is made from an ordinary aerial photograph by optical-mechanical correction of the radial relief displacement and scale differences with help of an orthophoto pro jector. With modern equipment orthophotography ima gery of excellent quality can be produced. The photographic quality is not notably affected by the projection process. The topographic quality (pos itional accuracy) depends to a large degree on the accuracy of the available digital terrain model but in normal circumstances errors in position should not exceed the order of magnitude of 5-10 m on orthophotography at a scale of 1:10,000 (< 1 mm in the orthophoto). At these scales such an accuracy for an engineering geological map is quite accept able. Orthophotography can be printed on the (uni form) scale of the map on which the engineering geological information must be plotted. The transfer of data from a photo to its orthophoto is still extra work but the sources of error have decreased strongly as features on the photo and orthophoto can be correlated much easier with each other than fea tures from photo and map. Orthophotography can be made from aerial photo graphy, but also from terrestrial photography if a metric camera was used to make the terrestrial photographs (Grabmaier, 1983). Figure 1 shows part of an aerial orthophotograph at a scale of 1:5,000 onto which the contour lines of a topographic map with contour line interval of 10 m are printed. This orthophotograph has been prepared from original negatives at a scale of 1:22,000. STEREO ORTHOPHOTOGRAPHY With help of the orthophoto projector a "stereo mate" can be produced of photography overlapping the photography from which the orthophotograph was prepared. Into the stereomates an artificial relief displacement in x direction is introduced which causes x parallaxes between orthophotograph and stereomate which equal the x parallaxes of the original stereo model. When orthophotographs and stereomate are viewed stereoscopically with a mirror stereoscope a three dimensional image of the terrain is visible which is not distinguishable from the original stereo model. When stereo orthophotography are prepared exactly at the scale of the map to be prepared the overlay on which the photo interpretation results are plot ted can be used directly as a map after introduc tion of the contourlines from a topographic base map. INTERPRETATION OF (STEREO) ORTHOPHOTOGRAPHS Aerial photography. The interpretation of aerial stereo orthophotogra phy follows exactly the same lines as the inter pretation of normal aerial photography. Engineering soil and rock units, slope instability phenomena and erosion features can be recognised and outlined on the photo-overlay (Soeters and Rengers, 1981). A comparison of the quality of the engineering geo logical interpretation between stereomodels of aerial photographs and their orthophotographs and stereomates has shown that orthophotography gives comparable and in some cases even better results (Sissakian, Soeters and Rengers, 1983). Terrestrial photography. In cases where vertical outcrops have to be mapped in detail for engineering purposes, the transfer of information obtained from stereoscopic interpret ation of overlapping terrestrial photography to a base map is particularly difficult. The reference plane should be a vertical plane on which the in terpretation results must be plotted with parallel projection in a direction normal to the reference plant. In this case orthophotography (fig. 3) can be particularly useful and the digital terrain model obtained photogrammetrically from the metric photo graphy can be used to plot as well an equidistance

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