GIS-based Spatial Viewshed Analysis of Cableway Construction Projects in Scenic Areas

GIS and GPS are used for the quantitative analysis of visual landscape impact of the old and new Cloud Valley Cableway in the Yellow Mountain.The results show that viewshed,quantity of visible sensitive scenic areas,and visible length from the tour routes of the new cableway are much smaller than those of the old one,so the new cableway has limited impact on visual landscapes of the scenic area,and basically meets the requirement of not damaging natural landscape features of the Yellow Mountain.GIS-and GPS-based spatial viewshed analysis methods have promising prospects in researches on landscape infl uence of scenic areas,and both of them are also signifi cant technical supports for the environmental protection verifi cation of construction projects in scenic areas.

Parallel algorithm for viewshed analysis on a modern GPU

Spatial analysis,including viewshed analysis,is an important aspect of the Digital Earth system.Viewshed analysis is usually performed on a large scale,so efficiency is important in any Digital Earth application making these calculations.In this paper,a real-time algorithm for viewshed analysis in 3D scenes is presented by using the parallel computing capabilities of a graphics processing unit(GPU).In contrast to traditional algorithms based on line-of-sight,this algorithm runs completely within the programmable 3D visualization pipeline to render 3D terrains with viewshed analysis.The most important difference is its integration of the viewshed calculation with the rendering module.Invisible areas are rendered as shadows in the 3D scene.The algorithm process is paralleled by rasterizer units in the graphics card and by vertex and pixel shaders executed on the GPU.We have implemented this method in our 3D Digital Earth system with the DirectX 9.0c API and tested on some consumer-level PC platforms with interactive framerates and high image quality.Our algorithm has been widely used in related systems based on Digital Earth.

A Comparative Study of Digital Terrain Data for Visibility Analysis in the Planning and Management of Scenic Resources

A DEM （digital elevation model） was once used to calculate viewsheds in the early days of GIS applications. The emergence of LiDAR （light detection and ranging） data which are likely to have higher spatial resolutions than traditional DEMs contributed to the improvements of calculation accuracy greatly. The objective of this study is to validate that the LiDAR data calculate and predict a viewshed better than the traditional low-resolution DEMs with 10 m and 30 m spatial resolutions. Using digital terrain data acquired for part of the Nez Perce National Forest in Idaho, calculation accuracy for viewsheds was scrutinized in depth. Four hundred and eighty four （484） observation points were selected randomly to compute viewsheds from the 1-m pixel, bare-earth LiDAR data and from the traditional 10 m and 30 m DEMs. The comparison of their RMSEs （root-mean-squared-error） values proves the newer generation of digital terrain data produces more accurate viewsheds than ones generated from the traditional DEMs. Analyses of variance and t-tests show the viewsheds calculated from various terrain models are statistically different. Therefore, findings from this study suggest that high-quality LiDAR data, if available, should be used for decision-making in planning for and the management of the scenic resources.

Reconstruction Design of Zaozhuang Gangue Hill Based on the Interaction of“Scenery”and“View”

Gangue hill is the associated accumulation landscape of long-term coal mining.There are a large number of gangue hills left in coal mining cities,which not only causes ecological damage but also affects the urban environment,thus becoming the focus of urban landscape transformation of coal mining cities.With the increase of people’s demand for ecological leisure,it has become the first choice to transform gangue hill and its surrounding areas into community parks.From the perspective of urban space and landscape system,as a huge regeneration landform in the city and a unique landscape in the mining area,gangue hill not only needs to be afforested,but also needs to be connected with mining heritages and landscape nodes in the city to form the interaction between“scenery”and“view”,so as to form an integrated mining cultural landscape system at the urban level.On the basis of this concept,taking the gangue hill of Zhongxing in Zaozhuang City as an example,this paper quantitatively analyzes the best landscape construction site in the gangue hill via viewshed analysis in GIS.Through this method,the gangue hill and Zhongxing mining heritage are closely combined,so as to establish the interactive relationship between“scenery”and“view”.It can guide the planning and design of sightseeing route and footpath system,and also provide a technical support for the design of community parks transformed from gangue hills.