共查询到20条相似文献，搜索用时 15 毫秒
1.
行政区划图自动着色的混合遗传算法 总被引：1，自引：0，他引：1
结合贪心算法的局部搜索能力与遗传算法的全局搜索能力,研究了政区图四色着色问题的混合遗传算法,并在此基础上提出了一些改进措施。试验结果表明,这种混合遗传算法能有效地解决行政区划图自动着色问题,并取得了较好的结果。 相似文献
2.
旅行商路径优化问题是经典的网络分析问题之一。由于旅行商问题具有NP Hard特性,主要通过智能优化方法或启发式算法来获得近似最优解。然而,单一智能优化方法存在运算量过大、参数选择苛刻,对初值依赖性强等缺陷,很难快速实现全局优化。结合多种优化机制和邻域搜索结构设计混合启发式算法可在一定程度上解决这一问题。本文结合遗传算法的全局寻优能力和禁忌搜索的记忆功能,设计实现了一种基于分散集中策略的禁忌遗传算法,即采用遗传变异算子作为分散策略构造邻域,开辟新的搜索空间,有效提升获得全局最优解的概率;将禁忌搜索作为集中策略进行局部寻优,避免迂回探测,充分体现禁忌搜索较强的“爬山”能力,并通过实际交通网络和不同规模的节点集合,从求解精度、稳定性和效率三个方面对算法进行了评价。结果表明,本文提出的交通网络旅行商路径优化的禁忌遗传算法平均求解精度比禁忌搜索算法提高了9%,略优于ArcGIS;当与ArcGIS求解的TSP路径长度差异在1%以内时,禁忌搜索算法已经难以获得对应精度的TSP路径,而禁忌遗传算法效率比遗传算法提高了50%。且禁忌遗传算法具有很好的并行化潜力。 相似文献
3.
设计了基于障碍距离的优化算法,解决突发事件应急联动中复杂地理环境下最短路径的寻优求解问题。在详细分析地理空间高程、坡度、障碍物等空间信息的基础上,通过计算搜索空间、搜索方向和网络弧段权值构建网络拓扑关系网,并利用遗传算法对最优路径进行寻优求解。 相似文献
4.
Mapping Large Spatial Flow Data with Hierarchical Clustering 总被引：6，自引：0，他引：6
It is challenging to map large spatial flow data due to the problem of occlusion and cluttered display, where hundreds of thousands of flows overlap and intersect each other. Existing flow mapping approaches often aggregate flows using predetermined high‐level geographic units (e.g. states) or bundling partial flow lines that are close in space, both of which cause a significant loss or distortion of information and may miss major patterns. In this research, we developed a flow clustering method that extracts clusters of similar flows to avoid the cluttering problem, reveal abstracted flow patterns, and meanwhile preserves data resolution as much as possible. Specifically, our method extends the traditional hierarchical clustering method to aggregate and map large flow data. The new method considers both origins and destinations in determining the similarity of two flows, which ensures that a flow cluster represents flows from similar origins to similar destinations and thus minimizes information loss during aggregation. With the spatial index and search algorithm, the new method is scalable to large flow data sets. As a hierarchical method, it generalizes flows to different hierarchical levels and has the potential to support multi‐resolution flow mapping. Different distance definitions can be incorporated to adapt to uneven spatial distribution of flows and detect flow clusters of different densities. To assess the quality and fidelity of flow clusters and flow maps, we carry out a case study to analyze a data set of 243,850 taxi trips within an urban area. 相似文献
5.
协同模型与遗传算法的集成 总被引：4，自引：4，他引：4
郑肇葆 《武汉大学学报(信息科学版)》2001,26(5):381-386
提出协同模型中蚁群算法和遗传算法集成的方案，用于生成纹理分类的模板。介绍了蚁群算法的原理和集成方案的实施步骤，以及在搜索最优解过程中蚁群移动方向的决策方法。为了验证集成方案的正确性，对航空影像的居民地、灌木、水田、山地、旱地5种目标进行了识别试验，并与仅使用遗传算法的结果进行了比较。试验结果表明，该集成方案的识别效果有明显的提高。 相似文献
6.
搜索离散目标群的边界是地理信息系统(GIS)和地图学中一个重要问题,传统的算法是基于矢量数据的。本文提出了基于栅格数据搜索离散目标群的边界的新方法,并用两个点群算例介绍了用闭运算搜索边界的方法与流程,为数字高程模型生成、地图学等提供一种新的边界搜索方法。 相似文献
7.
ZHENGZhaobao 《地球空间信息科学学报》2002,5(1):1-6
In the photogrammetry,some researchers have applied genetic algorithms in aerial image texture classification and reducing hyper-spectrum remote sensing data.Genetic algorithm can rapidly find the solutions which are close to the optimal solution.But it is not easy to find the optimal solution.In order to solve the problem,a cooperative evolution idea integrating genetic algorithm and ant colony algorithm is presented in this paper.On the basis of the advantages of ant colony algorithm,this paper proposes the method integrating genetic algorithms and ant colony algorithm to overcome the drawback of genetic algorithms.Moreover,the paper takes designing texture classification masks of aerial images as an example to illustrate the integration theory and procedures. 相似文献
8.
Francis Kamau Muthoni Frederick Baijukya Mateete Bekunda Haroon Sseguya Anthony Kimaro Tunrayo Alabi 《国际地球制图》2019,34(4):368-390
This paper generates an extrapolation suitability index (ESI) to guide scaling-out of improved maize varieties and inorganic fertilizers. The best-bet technology packages were selected based on yield gap data from trial sites in Tanzania. A modified extrapolation detection algorithm was used to generate maps on two types of dissimilarities between environmental conditions at the reference sites and the outlying projection domain. The two dissimilarity maps were intersected to generate ESI. Accounting for correlation structure among covariates improved estimate of risk of extrapolating technologies. The covariate that highly limited the suitability of specific technology package in each pixel was identified. The impact based spatial targeting index (IBSTI) identified zones that should be prioritized to maximize the potential impacts of scaling-out technology packages. The proposed indices will guide extension agencies in targeting technology packages to suitable environments with high potential impact to increase probability of adoption and reduce risk of failure. 相似文献
9.
Stephen Wise 《Transactions in GIS》2002,6(3):327-337
Data capture from paper maps remain a slow and costly part of many Geographic Information System projects. In this paper a simple method is described which makes use of the facilities of desktop graphics software to capture raster data from scanned thematic maps. The first stage is to use the flood fill tool to identify the regions of the map that represent the data values and set them to a separate colour for each thematic category. This edited image is then imported into a GIS, where a specially written majority filter is used to classify any remaining pixels to produce a raster GIS layer. The technique is tested on samples from three maps, giving accuracy levels of over 90% in all cases when compared with digitising the same maps by hand. The technique could be useful for situations where a rapid and simple means of data capture is needed and could be developed further by drawing on techniques for contextual classification rather than relying on a general purpose flood fill algorithm. 相似文献
10.
空间分区问题是将基本的空间单元遵照多个规划准则组合成若干较大簇即空间区域的过程,保证区片的连续性是其空间硬约束条件。近年来,空间分区问题在政治选举区域划分,市政公共设施选址布局,社会紧急服务以及商业销售区域的划分等领域有着十分重要的应用。目前,空间分区问题的研究成果较为零散,缺乏较系统的归纳和总结,而且其应用也大多集中在传统领域。为此,本文对空间分区问题的通用模型进行了总结,并对多目标禁忌搜索算法解决此类问题的流程和核心问题作了详细阐述,最后本文将研究成果应用到江夏区高产农田整理区片自动划分中,并取得了较好的效果。 相似文献
11.
彩色影像的遗传自适应增强 总被引：1，自引：0，他引：1
提出了一种彩色色形像自适应增强的算法，此算法充分利用了彩色影像饱和度和亮度所包含的信息，并利用遗传算法自适应地调整增强系数。对于不同的影像，本文算法均能使其对比度，目标边缘以及纹理特征得到增强。 相似文献
12.
空间聚类不仅应考虑GIS对象属性特征的相似性,还应考虑对象的空间邻近性。不同属性、位置特征在聚类中起到的作用不同。采用信息熵方法计算空间距离中各属性距离、位置距离的权重,权值大小用于度量相应特征在fuzzy c-means隶属度计算时的作用大小,并引入相似性指标,当两个聚类之间的相似度高于某个合并阈值时,则对应的一对聚类进行合并,从而克服需预先设置聚类类数的问题。通过应用实例的聚类有效性分析,与普通空间距离相比,基于空间加权距离的FCM算法具有稳定性和有效性。 相似文献
13.
阐述了GIS网络分析中不确定性选址问题的基本模型及特性。从问题的定义可知其为NP完备类问题。推导了最优解在紧条件的下界算法,并结合广义Powell算法及遗传算法,提出了不确定性选址问题的混合遗传算法,实验证明,在最优解的品质和收敛速度上都达到了比较好的效果。同时,实验的结果从另一个角度证明,如果兼顾收敛速度和解的品质这两个指标,单纯的遗传算法未必比其他搜索算法更优越,采用一些局部搜索性能较好的算法结合遗传算法,可以从两方面改善求解效果。 相似文献
14.
针对一些通用的空间数据的数据交换格式进行了研究，并就不同数据格式的数据量进行了对比实验。结果表明，在栅格数据中，．bmp格式的数据量最大，.jpg格式和．gif格式的数据量较小；矢量格式的数据量的大小与空间数据的属性有关，在几种常用的矢量格式中，．e00格式的数据量最大。 相似文献
15.
《The Cartographic journal》2013,50(1):21-26
AbstractThe spatially discontinuous choropleth map is a poor representation of the underlying continuous distribution of population density. A possible alternative is to derive dasymetric maps at a fine spatial resolution by making use of satellite imagery in a geographical information system. However, there are cartographic problems when these maps are displayed and further processing is needed in order to obtain approximations to a continuous density surface. Isarithmic maps of these density surfaces retain a high degree of spatial accuracy while providing pleasing and highly adaptable presentations.The methods used to generate dasymetric and isarithmic maps are readily implemented in most raster based geographical information systems. For example, the classification of remotely sensed imagery, the subsequent processing and integration of data, and most of the cartographic display, were all undertaken in this work using the low cost IDRISI GIS that operates on standard IBM PC compatible hardware. 相似文献
16.
SUGuozhong YANLi LIUNan LIURenyi 《地球空间信息科学学报》2004,7(3):180-186
A practical method for visualizing flood area and evaluating damage is presented, which consists of two technical approaches: self-programming and adapting commercial GIS platforms. The low-cost and easy-to-use GIS-Based model developed by self-programming can meet current requirements of most local authorities, especially in developing countries. In this model, two cases, non-source flood and source flood, are distinguished and the Seed-spread algorithm suitable for source-flood is discussed; The flood damage is assessed by overlaying the flood area range with thematic maps and other related social and economic data. and all the-matic maps are converted to raster format before overlay analysis. Two measures are taken to improve the operation efficiency of speed seed-spread algorithm. The accuracy of the model mainly depends on the resolution and precision of the DEM data, and the accuracy of registering all raster layers and the quality of attribute data. 相似文献
17.
A practical method for visualizing flood area and evaluating damage is presented, which consists of two technical approaches: self-programming and adapting commercial GIS platforms. The low-cost and easy-to-use GIS-Based model developed by self-programming can meet current requirements of most local authorities, especially in developing countries. In this model, two cases, non-source flood and source flood, are distinguished and the Seed-spread algorithm suitable for source-flood is discussed; The flood damage is assessed by overlaying the flood area range with thematic maps and other related social and economic data. and all thematic maps are converted to raster format before overlay analysis. Two measures are taken to improve the operation efficiency of speed seed-spreed algorithm. The accuracy of the model mainly depends on the resolution and precision of the DEM data, and the accuracy of registering all raster layers and the quality of attribute data. 相似文献
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19.
AbstractIn this research, multicriteria decision analysis with pairwise comparison weighting method was utilized to determine the suitable locations for vineyard plantation in Sarkoy region of Turkey. Soil maps, meteorological measurements, slope, aspect and elevation maps were used as input to conduct spatial analysis. Different methods were compared and pairwise comparison method was identified as the most appropriate method of weighting for this spatial analysis. Current vineyard areas were determined using Worldview-2 imagery and their spatial distribution compared with the resulting suitability map to determine the current suitability. Comparisons showed current vineyards were mostly established in locations where suitability map expresses low capability. Further inspection unveiled that, these low capability lands are closer to the transportation networks and city/county centres that tend to be in sea level elevations as opposed to vine grapes thriving in higher altitudes. Results also enabled providing suggestions on alternative sites for new vineyard plantation. 相似文献
20.
提出了一种适于数字栅格地图版权保护的离散傅立叶变换域自适应数字水印嵌入算法。该算法通过对数字栅格地图进行分块傅立叶变换和频谱分析,结合人类视觉系统,能够自适应地确定地图的纹理区域,将水印信息以加性法则嵌入到纹理区域的傅立叶变换域中频系数内。不同分块大小的栅格地图水印算法具有不同的鲁棒性。对2×2、4×4和8×8分块的水印算法进行了比较分析,结果表明,2×2分块水印算法不仅具有较好的透明性,而且对诸如叠加噪声、JPEG压缩、几何裁剪、图像增强等攻击均具有更好的鲁棒性,整体性能优于4×4分块和8×8分块算法。 相似文献