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:: [THP-2 GIS INTEGRATION]

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: GIS-Guided Road Extraction form Satellite Imagery. J. Van Cleynenbreugel, F. Fierens, P. Suetens, A. Oosterlinck

Document type:: Multivolume work

Structure type:: Chapter

653 3.2 Exploiting DTM knowledge In the second case study, we use a Digital Terrain Model (DTM) to guide road extraction. In particular, we are interested in the influence of the terrain on the appearance of roads in mountainous areas. Generally, these roads follow contours in order to minimize con struction and travelling effort. The following is a generic model obtained for delineating mountain-roads : • in general, mountain-roads are serpentine • mountain-roads usually follow ground contours • if contours are not followed, then altitude differences are minimized • the slope along the track of a road has a maximal value A part of a mountainous country SPOT image and the result of applying the TON detector to it are shown in Fig. D1 and Fig. D2, respectively. From the latter, line seeds having high response are chosen. If a seed has a number of points of high line curvature, it is assummed to be part of a sinuous road. From the DTM an average contour line connecting the individual pixels of the seed is obtained. This is illustrated by the white line on Fig. D3. The DTM image itself was obtained by TIN-interpolating contour lines, manually digitized from an existing topographic map. The contour line obtained in this way is used as a deformable model to extend the seed element according to the second statement from the generic model. This iconic deformation procedure inherits from a general method known as snakes, see [2]. By elastically deforming the contour line under influence of an external photometric force-field and of an internal energy, an optimal road outline is obtained. The force-field used in this case is the magnitude response from the line detector and displacements in this field are guided by the detector’s directional response. Our development tool offers flexible ways to tune parameters and gather data about the line’s movement. A result of this method is shown in Fig. D4, where part of the contour line from Fig. D3 has been deformed to the road outline. Work is under way to include the DTM itself (and not just a contour line out of it) in the optimization process. Also the combination of the serpentine lines into a network is under investigation. 3.3 Exploiting HYDROGRAPHIC knowledge In the third case study, a hydrographic map is used as an index in the image data to look for roads almost parallel to rivers. The position of a road in a terrain near a river is related to the order of that river in the hierarchical drainage network it is part of. Again, a generic model was obtained from discussion with cartographers : • roads are usually parallel to contours tracing the valley of the river rather than to the river itself

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