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91.
三维陡崖符号的自动建模研究 总被引：2，自引：1，他引：1
针对三维地形图中某些地貌符号难以建模的问题,以陡崖符号为例,提出了一种基于不规则三角网自动提取陡崖边缘线的方法,根据不同光照条件下的视觉感受规律,建立了陡崖符号的光照模型,并对其数学表达进行了研究,介绍了陡崖符号的自动建模流程,有助于其他类似地貌符号模型的自动建立。 相似文献
92.
LIDAR monitoring of mass wasting processes: The Radicofani landslide, Province of Siena, Central Italy 总被引：1，自引：0，他引：1
Marco Baldo Claudio Bicocchi Ugo Chiocchini Daniele Giordan Giorgio Lollino 《Geomorphology》2009,105(3-4):193-201
The Radicofani Basin, stretching about 30 km NW–SE, is an intra-Central Apennine basin connected to Pliocene–Pleistocene extensional tectonics. It consists of an Early to Middle Pliocene succession including essentially shelf pelites. In the Radicofani area, province of Siena (Tuscany region), morphodynamic processes are very frequent with widespread badlands and rapidly evolving mudflows. In order to evaluate the general instability of the Radicofani area, geological and geomorphological surveys were carried out. The 1954, 1990 and 2003 aerial surveys allowed a comparison of the changes in the various morphological aspects of the study area, which suggested an increase in slope instability with time. A new complex translational landslide evolving into mudflows, activated during the winter of 2003, was monitored using an experimental system based on terrestrial LIDAR (Light Detection and Ranging) and GPS (Global Positioning System) technologies. This system allowed the monitoring of the morphologic and volumetric evolution of the landslide. A comparison of the monitoring data of October 2004, June 2005, May 2006 and May 2007 points out that the evolution is characterised by the sliding of displaced materials. A volume of about 1300 m3 of materials was removed during the period 2004–2005, 300 m3 for 2005–2006, and 400 m3 for 2006–2007. The greater initial mass movement probably reflects a greater static imbalance during the early period of landslide movement and increased rainfall. Therefore, the proposed monitoring system methodology allows the numerical evaluation of the landslide morphological evolution and to validate the landslide evolution model based on geological and geomorphological field surveys. 相似文献
93.
Modeling of dam-break flooding in an urban residential area in southern California is presented. Modeling is performed using BreZo, an unstructured grid, Godunov-type, finite volume model that solves the shallow-water equations. The model uses terrain data from a 1.5 m Light Detection and Ranging (LiDAR) Digital Terrain Model (DTM) and contour data depicting the reservoir and breach geometry. A spatially distributed Manning coefficient based on a landcover classification derived from digital orthophotos and vector data (e.g., parcel outlines) is also used, and the interception of flow by storm drains is modeled with sink terms in the 2D continuity equation. The model is validated with flood extent and stream flow measurements, and a sensitivity analysis is completed to identify the necessary level of data and model complexity for accuracy purposes. Results show street depressions in the land surface should be resolved by the computational mesh for flood extent and stream flow accuracy. A ca. 5 m resolution mesh that spans streets by approximately 3 cells achieves a good balance between accuracy and computational effort. Results also show that heterogeneous resistance is important for stream flow accuracy, and the interception of overland flow by storm sewers is important for flood extent accuracy. The sensitivity of predictions to several additional factors such as the reservoir level, breach geometry and DTM source (LiDAR, National Elevation Data, Shuttle Radar Topography Mission Data) is also reported. 相似文献
94.
Geodiversity is a landscape characteristic related to the heterogeneity of the physical properties of the earth surface. In this work, we quantify and compare geodiversity in several geodynamic zones of the Iberian Peninsula. For this purpose, we have developed a geographic information system (GIS) procedure to carry out a regional terrain classification based on geodiversity factors. A classification process helped to produce a morphometric map (10 classes), a morphoclimatic map (five classes) and a geological map (15 classes). These three maps were combined using an overlay operation (union) to obtain the final terrain classification (419 classes), which was then applied to calculate diversity landscape indices. The latter were calculated using common landscape diversity indices (Patch Richness Density, Shannon's Diversity Index, Shannon's Evenness Index, Simpson's Diversity Index and Simpson's Evenness Index), provided by FRAGSTATS free software. These indices were calculated for the whole landscape of the main Iberian geological regions, thus revealing a close relationship between some index values and the geological and geomorphological characteristics. The highest diversity values are associated with Alpine collisional orogens and reactivated chains of the Precambrian‐Palaeozoic massif. Intraplate orogen with sedimentary cover, characterized by extensive planation surfaces, have lower values. Mesozoic areas with no significant tectonic deformation and Cenozoic basins are characterized by the lowest diversity values. Amongst the latter, the major diversity is associated with the most dissected basins, which also present higher morphoclimatic variety. Though depending on the chosen scale and the landscape classification criteria, these indices provide an objective assessment of the regional geodiversity of Iberia. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
95.
机载激光雷达系统的应用与数据后处理技术 总被引：11，自引：0，他引：11
综述了机载激光雷达系统的组成、工作原理、应用和数据后处理技术,着重介绍机载激光雷达数据中的信息提取的有关算法,这些算法包括DEM、DTM提取、房屋提取与房屋几何模型的3D重建、道路网提取、森林参数的获取等。 相似文献
96.
张海堂 《测绘与空间地理信息》1999,22(4):7-8
LineBoss(线博士)系统是一种在传统的利用DTM进行线路初步设计的基础上,利用虚拟现实技术和计算机技术,建立虚拟地景环境并在其中进行线路初步设计的智能型系统。对其软件制作技术和系统特点进行了介绍。 相似文献
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Over the past decades, several filters have been developed to derive a Digital Terrain Model (DTM) from a Digital Surface Model (DSM), by means of filtering out aboveground objects such as vegetation. In this filtering process, however, one of the major challenges remains to precisely distinguish sharp terrain features, e.g. ridges, agricultural terraces or other anthropogenic geomorphology such as open-pit mines, riverbanks or road ramps. Hence, loss of elevation data around terrain edges (and consequent smoothing) is very common with existing algorithms. In terraced landscapes, the preservation of precise geomorphology is of key importance in digital terrain analyses, such as hydrologic and erosion modelling, or automatic feature recognition and inventorying. In this work, we propose a new filtering method called TERRA (Terrain Extraction from elevation Rasters through Repetitive Anisotropic filtering). The novelty of the algorithm lies within its usage of terrain aspect to guide the anisotropic filtering direction, therefore maximising the preservation of terrain edges. We derived six DTMs from DSMs using UAV Structure from Motion (SfM) photogrammetry, laser altimetry and satellite sources (grid resolutions ranging from 0.1–1.0 m). The results indicated a close agreement of DTMs filtered using the TERRA algorithm and reference DTMs, while terrace risers were well preserved even under thick canopies of vines and trees. Compared to existing filtering approaches, TERRA performed well in minimising Type I errors (false ground removal), while Type II errors occurred locally where vegetation was covering the terrace edges. Given the promising filtering performance, and supported by the minimal requirements of parameterisation and computation, the TERRA algorithm could be a useful tool in DTM preparation for digital terrain analysis of agricultural terraces and similar hillslopes characterised by a complex mosaic of sharp terrain and non-terrain features. 相似文献