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排序方式: 共有299条查询结果,搜索用时 31 毫秒
261.
基于数字栅格地图的数据特性,运用小波变换工具,结合人类视觉系统特征,提出一种自适应的数字栅格地图可见水印算法。首先,对可见水印信息进行扩展等预处理;然后通过计算数字栅格地图的视觉重要区域来选择水印嵌入位置,水印嵌入位置由人类视觉系统特征和地图数据特性共同决定;最后,将可见水印自适应地嵌入地图所选择嵌入区域的小波域中。对提出的水印算法进行了试验分析,结果表明,该算法不仅具有良好的抗差性,同时还较好地保持了可见水印和原地图的视觉特征,以一种更积极有效的方式保护了数字栅格地图的版权。 相似文献
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Yosoon Choi Choon Sunwoo Keith C. Clarke 《International journal of geographical information science》2013,27(12):1541-1567
A new raster‐based GIS model that combines multi‐criteria evaluation and least‐cost path analysis was developed to determine the optimal haulage routes of dump trucks in large scale open‐pit mines. The model logic can consider multiple criteria simultaneously (i.e. speed, water body, ore body, curve, visibility, haul road maintenance) and can rate the adverse factor scores of truck movement using fuzzy membership functions. After establishing the weights of five factors by pairwise comparisons, the average adverse score grid can be generated by the weighted linear combination of factor and constraint scores. New software, called Dump Traveler, was implemented to improve the availability of the developed model. An application to the Roto South pit in the Pasir open‐pit coal mine, Indonesia, showed that the software can provide rational solutions to determine the optimal routes on truck haulage operations. Moreover, the layout of available haul roads can be evaluated to consider the trade‐off between road maintenance costs and the potential for traffic jams. Variations of weights for factors were found to be sensitive to the optimal haulage routes determined by least‐cost path analysis. The software provides both optimal routes on truck haulage operations and approximately estimated travel times along the routes, therefore it can support other truck dispatching software that mainly considers scheduling problems. 相似文献
264.
Alexandre B. Gonçalves 《International journal of geographical information science》2013,27(7):983-996
The computation of least-cost paths over a cost surface is a well-known and widely used capability of raster geographic information systems (GISs). It consists in finding the path with the lowest accumulated cost between two locations in a raster model of a cost surface, which results in a string-like, thin and long sequence of cells. In this article, a new extension of raster-based least-cost path modelling is proposed. The new modelling approach allows the computation of paths or corridors with a fixed width, larger than one cell. These swaths are called wide paths and may be useful in circumstances where the detail level of the raster cost surfaces is higher than the width of the desired path or corridor. The wide path model presented in the article is independent of the choice of least-cost algorithms, because the transformation from regular to wide paths is applied to the construction of nodes and edges of an induced graph. The article gives the foundations and discusses the particularities of such paths, regardless of the imposed width, and explores the difference from the usual least-cost path model. Test cases were included, one hypothetical and the other with real data. The results are coherent and indicative of the applicability of wide paths. 相似文献
265.
Takeshi Shirabe 《International journal of geographical information science》2013,27(7):1097-1116
From a single-attribute raster layer in which each cell is assigned a numerical value, a connected set of a specified number of cells that has the maximum (or minimum) total value is selected. This is a highly common decision problem in the context of raster-based geographic information systems (GIS) and seems general enough to deserve inclusion in the standard functionality of such systems. Yet it is a computationally difficult optimization problem, for which no efficient exact solution method has been found. This article presents a new dynamic programming-based heuristic method for the problem. Its performance is tested with randomly generated raster layers with various degrees of spatial autocorrelation. Results suggest that the proposed heuristic is a promising alternative to the existing integer programming-based exact method, as it can handle significantly larger raster data with fair accuracy. 相似文献
266.
矢量地图叠加分析在实际场景使用中经常需要处理各种大规模复杂空间数据,因此算法整体分析效率的提升尤其重要.该文重点针对较大多边形对象和大量较小多边形对象的叠加分析使用场景,提出了一种有较强针对性的基于非均匀多级网格索引的矢量地图叠加分析(Non-uniform Multi-level Grid Index Overlay,NMGIO)算法,包括索引构建、网格过滤、叠加计算、拓扑构面4个步骤,通过对待分析数据集和叠加对象双向建立非均匀多级网格索引,利用数据的空间分布特点从根本上提升叠加分析效率.同时给出了算法整体时间复杂度和由C++语言实现的原型系统叠加分析效果验证. 相似文献
267.
This study applies a spatial fuzzy multi‐criteria evaluation model to determine agricultural feasibility in China based on physical variables (accumulated temperature, sunshine, precipitation, hydrology, elevation and soil properties). The resulting agricultural feasibility index layer is combined with nightlight images (1992‐2013) to determine the spatiotemporal variation of urban encroachment on feasible agriculture land. It reveals the severity of agricultural land losses to urbanization. 相似文献
268.
高斯两步移动搜索法的模型研究——以上海市绿地可达性为例 总被引:5,自引:2,他引:3
合理的配置公共服务设施对城市的现代化建设至关重要。空间可达性是度量公共服务设施配置是否合理的方法之一。在诸多的研究方法中,高斯两步移动搜索法由于直观且运算简便,因而得到广泛应用。但该方法也有不足之处,本文运用格网GIS方法,以上海市的绿地空间可达性为例,对两步移动搜索法进行模型方法的改进研究,并对高斯两步移动搜索法和格网化的高斯两步移动搜索法进行对比分析,结果表明:后者可降低空间可达性的误差,提高可达性精度,对上海市绿地空间可达性反映更加真实、客观。如果选择合理的数据将其格网化,该方法也可以用于其他公共服务设施的空间可达性研究。 相似文献
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