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Visualizing Terrain
Published in Terry A. Slocum, Robert B. McMaster, Fritz C. Kessler, Hugh H. Howard, Thematic Cartography and Geovisualization, 2022
Terry A. Slocum, Robert B. McMaster, Fritz C. Kessler, Hugh H. Howard
Plan oblique relief is a term coined by Bernhard Jenny and Tom Patterson (2007) to describe a digital technique similar to conventional shaded relief maps, but that causes relief to “stand up” and thus provide a more easily seen 3-D view, and yet preserve the geometric accuracy of conventional planimetric shaded relief maps. Jenny and Patterson argue that Raisz's maps were successful, in part because of his use of this technique, albeit in a manual world. Figure 23.18 illustrates how plan oblique relief compares with conventional shaded relief in terms of the projecting rays of light that are used to create a map image. Assuming that virtual rays of light are directed at a DEM of the terrain, Figure 23.18A shows the resulting projected rays of light that reach the image plane (e.g., a computer display) for the orthographic approach used in conventional shaded relief. In contrast, Figure 23.18B shows the result for the plan oblique approach, where α is the inclination angle between the image plane and the projected rays of light, with lower values of α producing greater vertical exaggeration.
Urban Geologic Mapping
Published in Daniel T. Rogers, Urban Watersheds, 2020
General guidelines for constructing a geologic cross-section include: Choosing appropriate horizontal and vertical scalesProperly locating control points or points along the cross-section where stratigraphic sequences are knownEnsuring the legend incorporates and explains each geologic material and featureUsing appropriate symbols to identify each geologic unitUsing appropriate orientations and landmark featuresIncluding vertical and horizontal scalesIncluding a statement of vertical exaggeration
Geohazards
Published in White David, Cassidy Mark, Offshore Geotechnical Engineering, 2017
DeBlasio et al. (2004) and Elverhoi et al. (2005) used the BING model to back-calculate the evolution of two typical slides, part of the giant Storrega slide in Norway. The model was used to predict the run-out distance and deposition profile, which were compared with the field data; an example is shown in Figure 10.23. Figure 10.23a shows the analysis output with a vertical exaggeration of approximately 1:20 and Figure 10.23b shows the output at true scale to indicate the very low inclination at which the slide occurred. Adjusting the shear strength within the range of acceptable geotechnical values allowed run-out distances to be matched quite well. Deposition thickness was not well represented and the field data shows a higher deposition thickness on the steeper slope and a lower deposition thickness on the more gentle slope, contrary to the results obtained assuming a Bingham model with constant shear strength.
Structural elements of the southern Thomson Orogen (Australian Tasmanides): a tale of megafolds
Published in Australian Journal of Earth Sciences, 2018
M. P. Doublier, D. J. Purdy, R. Hegarty, M. G. Nicoll, H. Zwingmann
The effect of these structures in the basin seismic data may be subtle, in particular if displayed with normal aspect ratio; however, displaying the data with high vertical exaggeration (a technique common in basin seismic interpretation) allows the structures to be mapped out in greater detail (Figure 5).