交通矢量地图离散非线性校正算法

该文从交通矢量地图的基本特征出发,在深入分析矢量地图的网络拓扑结构的基础上提出了一种新的矢量地图自动校正算法,即：离散非线性校正算法。算法的关键在于离散块的选取以及所选取离散块内各节点的相应调整。通过对整个地图平面的分块非线性校正,在合理选取校正样本的情况下能够对整个地图的所有局部区域达到最优的校正。与传统的线性自动校正算法相比,这种算法可以有效地消除矢量地图中的非线性误差,理论上也有所深入。实验中将该算法应用于合肥、成都等城市的矢量地图校正中,取得了良好的校正效果。应用校正算法得到的交通矢量地图将为交通管理或监控导航系统提供准确的资料信息和更好的智能决策服务,从而给人们生活带来极大的便利。     

矢量地图的无损数据隐藏算法研究

在矢量地图中隐含水印信息,地图数据的质量往往由于水印的嵌入而受到影响。可逆水印技术(又称无损数据隐藏)具有完整恢复载体数据的能力,因而更加适用于矢量地图。基于差值扩大的思想,提出了一种应用于矢量地图的无损数据隐藏算法。算法根据矢量地图对数据精度的特殊要求提出了相应的水印嵌入条件,并通过修改地图中相邻顶点坐标间的差值来嵌入水印信息。水印的提取过程不仅能够得到隐藏信息,而且能够准确无误地恢复原始地图数据。采用两类地图进行实验,实验结果表明,算法在具有较强坐标相关性的地图中具有较高的嵌入容量,并且引入较低的扰动。算法的应用前景包括矢量地图数据的篡改鉴别、元数据格式兼容以及基于矢量地图的隐藏通信。     

A*算法在矢量地图最优路径搜索中的应用

在交通地理信息系统应用中,如何既快速又准确地找到最优路径是一个关键的问题.将人工智能领域的A*算法引入到矢量地图的最优路径搜索中来,论述了应用于矢量地图最优路径搜索的A*算法是一种完备的算法.同时,针对交通矢量地图的特点,提出了一种将矢量地图本身节点的数据结构和A*算法需搜索的节点数据结构在索引时相互联系,在计算时又相互分离的策略,提高了A*算法的执行效率.实验表明这种改进数据结构的A*算法在准确性和快速性方面都取得了令人满意的效果.     

基于GPS浮动车数据的矢量地图校正算法

针对矢量数字地图生成过程中产生的误差以及传统校正算法精度低、无法校正拓扑错误等不足,提出通过对GPS浮动车数据进行聚类分析,提取GPS浮动车数据中隐含的道路节点位置信息,对道路图层进行校正的算法。应用该算法,在VB6.0开发环境和MapInfo二次开发控件MapX支持下,实现了重庆市江北区道路图层中部分快速路的校正,校正后的道路通过与Google Earth比较,发现校正后道路图层拓扑明显比校正前更加吻合实际的道路拓扑。与传统常规方法相比,该算法无需选取控制点信息,能够很好地修正路网拓扑错误,适合实际应用中的复杂情形。     

基于矢量地图的无人机三维航线校正仿真

无人机三维航线校正执行过程中受到环境等因素影响,导致无法适应预定计划,易发生偏差,存在校正精准性较差的问题.基于矢量地图提出一种新的校正方法,首先利用LPA航线部署方法分布三维航线点,并通过检验局部一致性来防止重新对全局进行搜索,减少了干扰因素的阻碍与搜索空间范围;然后采用卡尔曼滤波算法准确定位无人机,通过路面监控站发出的方位信息来计算当前无人机与部署航线间的距离偏差,引入校正因子有效校正偏离航线,让无人机能够按照部署航线完成飞行任务.仿真结果说明,基于矢量地图方法具有较高的时效性和准确性,满足了实际应用需求.     

二维矢量数字地图的零水印算法

提出了一种新的二维矢量数字地图的零水印算法.该算法选择矢量地图的顶点作为重要特征,把地图按坐标进行平均分块并统计各个分块中的顶点个数,利用变换与加密构造出标志版权信息的水印图.由于该算法不对原始地图数据进行任何修改,这使得传统水印算法的稳健性、安全性和不可感知性之间的矛盾用这种特殊的方法得到了很好的解决.实验结果表明,该零水印算法能够抵抗多种常见的攻击,可以用来对矢量数字地图进行版权保护.     

基于DCT域的数字水印算法

提出一种矢量地图水印嵌入不依赖原始地图的盲提取算法,该算法在离散余弦变换域上转换而成.离散余弦变换的特性之一是对相互依赖的数据能够产生能量聚集效益,而矢量地图同一条边上点与点具有依赖关系,在一条边上依次选取8个顶点作一个集合,并对这组集合数据经变换导出离散余弦值,将水印加密嵌入其系数中.实验表明该算法对矢量地图经DCT变换未产生较大的差异.     

基于时空分析的地图匹配算法研究

地图匹配技术被广泛用于GPS导航、城市道路交通状态分析等领域。针对目前城市浮动车数据量日益庞大,地图匹配算法实时性差、匹配率不高的缺点,提出了一种基于时空分析的地图匹配算法。算法在对城市路网建立网格索引的基础上,综合考虑了空间几何、路网拓扑信息及上下文因素对选取GPS投影点的影响,大大提高了匹配效率和匹配精度。实验结果表明,算法能够满足工程应用中浮动车地图匹配的实时性和准确性。     

一种改进的Hausdorff距离地图匹配方法

目前的地图匹配算法分为在线和离线匹配两类。针对离线地图匹配中Marchal算法精度较低的问题,提出了一种改进的Housdorff距离匹配算法,利用航线方向角与Housdorff距离对Marchal匹配算法进行了改进。通过仿真试验的定性定量分析,新算法可以较好地纠正矢量数据不完整时产生的错误结果,很大程度上提高了匹配的准确性,可以为导航系统以及规划部门提供保障服务。     

矢量地图下最短路径问题的研究

本文讨论了矢量地图下的最短路径问题,就矢量地图下最短路径寻优算法的实现进行了深入的研究,并应用于具体的城市道路环境中进行检验,取得了较好的结果.     

Aligning archive maps and extracting footprints for analysis of historic urban environments

Archive cartography and archaeologist's sketches are invaluable resources when analysing a historic town or city. A virtual reconstruction of a city provides the user with the ability to navigate and explore an environment which no longer exists to obtain better insight into its design and purpose. However, the process of reconstructing the city from maps depicting features such as building footprints and roads can be labour intensive. In this paper we present techniques to aid in the semi-automatic extraction of building footprints from digital images of archive maps and sketches. Archive maps often exhibit problems in the form of inaccuracies and inconsistencies in scale which can lead to incorrect reconstructions. By aligning archive maps to accurate modern vector data one may reduce these problems. Furthermore, the efficiency of the footprint extraction methods may be improved by aligning either modern vector data or previously extracted footprints, since common elements can be identified between maps of differing time periods and only the difference between the two needs to be extracted. An evaluation of two alignment approaches is presented: using a linear affine transformation and a set of piecewise linear affine transformations.     

地图中道路的自动识别与重建

本文针对地图中具有一定宽度的道路的识别,提出一种双边信息判断方法,它有跟踪准确、有效地填补间隙、正确穿越交叉点和桥梁,且不需要对地图作去噪声和细化等预处理,因而具有识别速度快的优点。采用该方法,对1∶50,000实际地图进行处理,获得了满意的结果。     

地图信息的分层提取

提出了一种分层提取彩色地图信息的方法。首先根据一般地图中区域要素的结构和颜色特点，利用统计的方法实现区域规范化，这一步基本上不需要人工干预；然后采用模板匹配方法提取地图中的标识，这些识别出来的标识一方面作为一层信息被提取出来，另一方面对后面的道路的提取有着重要的作用；提取道路时，充分利用它们的颜色特征和连通特性，结合前面提取出来的标识以及地图中的其它要素对道路进行连接、修补处理。试验结果表明了该方法的有效性。     

地图中铁路、道路提取和恢复显示的方法

本文提出一种从军用地图中提取铁路、道路的半自动方法和自动恢复显示其在地图中标识方式的算法,从而进一步实现地图图形显示系统的多层次结构。     

Benefit of the future SPOT-5 and of data fusion to urban roads mapping

This article deals with the contribution of both the future SPOT-5 (which will produce images with the same bands as the existing SPOT 1-3 ones but with an improved spatial resolution) and a sensor fusion method to urban mapping. The ARSIS concept (in French: Amelioration de la Resolution Spatiale par Injection de Structures ) is used for sensor fusion. It allows the improvement of spatial resolution of the multi-band images, while preserving spectral information, by use of the high frequencies of panchromatic images. A well-proven method for urban mapping is then applied to all multi-spectral images available in the context of the study. A photo-interpretation of the latter confirms the benefit of fine image resolutions to urban roads mapping, in the limit of the sensor studied here. Then, when comparing the roads surface at all resolutions with reference extracted from accurate maps of the city, we demonstrate quantitatively that the finer the resolution, the more accurate the cartography.     

How much is built? Quantifying and interpreting patterns of built space from different data sources

Land-use/cover change (LUCC) has emerged as a crucial component of applied research in remote sensing. This work compares two methodologies, based on two data sources, for assessing amounts of land transformed from open to built space in three regions in Israel. We use a decision-tree methodology to define open and built space from remotely sensed (RS) Landsat data and a geographic information systems (GIS) platform for analysing 1:50 000 scale survey maps. The methodologies are developed independently, used to quantify and characterize the spatial pattern of built space, and then analysed for their strengths and weaknesses. We then develop a method for combining the built area maps derived from each methodology, capitalizing on the strengths of each. The RS methodology had higher omission errors for built space in areas with high vegetation levels and low-density exurban development, but high commission errors in the arid region. The GIS analysis generally had fewer errors, although systematically missed built surfaces that were not specifically buildings or roads, as well as structures intentionally omitted from the maps. We recommend using maps for baseline estimates whenever possible and then complementing the estimates with clusters of built areas identified with the RS methodology. The results of this comparative study are relevant to both researchers and practitioners who need to understand the strengths and weaknesses of mapping techniques they are using.     

A general approach for extracting road vector data from raster maps

Raster maps are easily accessible and contain rich road information; however, converting the road information to vector format is challenging because of varying image quality, overlapping features, and typical lack of metadata (e.g., map geocoordinates). Previous road vectorization approaches for raster maps typically handle a specific map series and require significant user effort. In this paper, we present a general road vectorization approach that exploits common geometric properties of roads in maps for processing heterogeneous raster maps while requiring minimal user intervention. In our experiments, we compared our approach to a widely used commercial product using 40 raster maps from 11 sources. We showed that overall our approach generated high-quality results with low redundancy with considerably less user input compared with competing approaches.     

大型油库消防救援寻路算法改进

大型油库区的地形不同于城市、山地等复杂的地形,虽然范围较大,但是油库区地形十分规整,油罐等建筑排列整齐,且在储油罐区的道路是笔直畅通的.根据这些特点,将标准的A^*寻路算法进行改进.一方面,根据油库地形结构简单,搜索节点相对少的特点,对A^*算法中搜索Open表中节点的数据结构进行改进,采用排序算法提高了搜索效率;另一方面,根据储油罐区道路笔直畅通的特点,将道路分为有障碍路段和无障碍路段,分而治之,提高整体的寻路效率.实验证明,将两种改进方法进行结合,寻路时间明显缩短,平均搜索效率提高6.86%.     

Knowledge Based Pipeline Network Classification and Recognition Method of Maps

Map recognition is an essential data input means of Geographic Information System (GIS). How to solve the problems in the procedure, such as recognition of maps with crisscross pipeline networks, classification of buildings and roads, and processing of connected text, is a critical step for GIS keeping high-speed development. In this paper, a new recognition method of pipeline maps is presented, and some common patterns of pipeline connection and component labels are established. Through pattern matching, pipelines and component labels are recognized and peeled off from maps. After this approach, maps simply consist of buildings and roads, which are recognized and classified with fuzzy classification method. In addition, the Double Sides Scan (DSS) technique is also described, through which the effect of connected text can be eliminated.