地图代数系统居民地编绘工艺过程及评价

采用地图代数系统对居民地编绘工艺进行设计和实验，并与常规编绘工艺比较，得出地图代数系统在技术、效率和质量上具有明显优势的结论。     

地图上曲线长度归算的分形方法研究

提出了一种基于分形理论的地图曲线长度归算方法，并给出了应用实例，为曲线长度归算的客观化、自动化提供了新的途径。     

Multi—scale Representation of Building Feature in Urban GIS

This paper aims at multiscale representation of urban GIS,presenting a model to dynamically generalize the building on the basis of Delaunay triangulation model.Considering the constraints of position accuracy,statistical area balance and orthogonal characteristics in building cluster generalization,this paper gives a progressive algorithm of building cluster aggregation,including conflict detection (where),object(who) displacement,and geometrical combination operation(how).The algorithm has been realized in an interactive generalization system and some experiment illustrations are provided.     

一种鲁棒的矢量地图数据的数字水印

数字水印是多媒体数据版权保护的一种有效方法。为了将水印技术应用于矢量地图数据的版权保护,根据矢量地图数据各要素层所合数据的多少,设计两种不同的数据分类规则,以实现嵌入不同大小的水印信息。通过仿真实验,可以看出算法具有很好的不可感知性和鲁棒性,尤其是抵抗矢量地图数据最常受到的对数据正常的增加、删除、修改、局部裁剪等更新操作。     

本质矩阵优化分解的相对位姿估计

针对从影像恢复摄像机相对位姿的问题,提出了一种基于李群表示的本质矩阵快速分解的位姿估计算法。通过加权最小二乘方法优化了本质矩阵;利用本质矩阵和平移向量的关系求出了平移向量;由本质矩阵和位姿参数的等式关系建立目标函数,基于姿态的李群表示推导了旋转矩阵迭代估计过程;优化了唯一解确定的约束条件,避免了特征点的三维重建。仿真实验和真实图像实验表明提出的算法精度和鲁棒性均优于传统算法,算法效率得到明显提高。提出的算法避免了矩阵奇异值分解运算和大量的矩阵计算,而且只需对两组解进行唯一解确定,能够实现相对位姿的快速高精度估计。     

环境监测信息空间表征技术研究与应用

随着环境问题的日益凸显及公众对环境问题的日益关注,如何将污染分布及发生规律、环境质量状况及变化趋势以科学、准确、直观的方式进行展示并以浅显易懂的方式传递给广大公众,是摆在环境管理者面前的一个问题.本文提出了环境监测信息空间表征定义,并介绍了基于GIS、大数据技术的环境监测信息空间表征的主要形式,包括:①点数据的空间表征;②线数据的空间表征;③面数据的空间表征;④三维可视化空间表征;⑤随时间变化的空间信息表征,以及各空间表征方法在环境监测中的应用.     

基于地图感受论的电子地图颜色设计模型的研究

针对在对电子地图的元素配色时遇到的配色效率低下的问题,本文基于地图感受论和电子地图的特点,提出了电子地图的颜色设计模型,该模型用于电子地图中颜色设计的一般过程,能够大大地提高颜色设计的效率。并利用该模型,探索了分层设色地图中海洋深度表的设计规律,可以帮助提高颜色设计效率和设计质量。     

Chain-based polyline tessellation algorithm for cartographic rendering

ABSTRACT

Although the extrusion of 1D polylines into a 2D polygon and the tessellation of the polygon into primitives has been performed in the field of computer graphics, the efficient, robust, and high-quality tessellation of thick polylines that supports various cartographic styles for polyline rendering remains a practical challenge. We examined and compared existing vertex-, segment-, and polygon-based algorithms, and present a chain-based tessellation algorithm for cartographic rendering: points in the polyline are classified into abrupt and smooth points according to their point spacing, angle and thickness. The polylines are then divided into abrupt and smooth chains by clustering points that are adjacent and of the same type. An optimal algorithm is also presented to continuously tessellate the smooth chains into minimum geometric primitives and efficiently tessellate the abrupt chains into geometric primitives. We implemented the proposed algorithm and present the results of robustness, efficiency, quality, and cartographic styling tests conducted on real-world polylines. The results indicate that this approach has substantial advantages when considering all four requirements (robustness, efficiency, quality, and the support for various cartographic styles).     

Cartographic Design Matters – A Comparison of Thematic Polygon Design

The number of web services providing cartographic data is increasing. A main challenge is to enable a user to combine these services, not only from a technical perspective, but also from a cartographic one. One common use case for these services is to create mashups based on thematic polygons on top of background maps. In this study we compare four cartographic designs of thematic polygons: only boundaries, transparencies, hatches and icons. The aim of the comparison is to investigate whether the designs are good for identifying the extent of the polygons and if the design disturbs the reading of the background map. The comparison is based on an eye-tracking study, where 24 participants performed polygon identification tasks as well as background search tasks. The study revealed that hatches were more efficient than the other designs for polygon identification. Hatches had significantly shorter total fixation times as well as scanpath lengths, possibly since the participants were able to identify the extent of the polygon solely based on the interior (i.e. the hatches), while for the other designs the participants were extensively reliant on the boundaries. However, the results also indicate that the hatches design disturbs the reading of the background map more than the other designs; hatches also appear visually unpleasant for many users. Since each design had its strengths and weaknesses, we recommend producers of services for thematic data to provide several designs so users can select an appropriate design for their own use cases.     

基于稀疏表示和字典学习的全色与多光谱影像融合

Pansharpening方法通过融合多光谱影像的光谱信息和全色影像的空间细节信息来得到高分辨多光谱影像。然而传统的Pansharpening方法易导致产生光谱扭曲和空间信息丢失现象。受到影像稀疏表示超分重建理论启发,本文提出了一种新的基于稀疏表示和字典学习的Pansharpening方法。该方法以影像的高频特征作为训练样本,通过字典学习的方法来获取高低分辨率影像字典,使用正交匹配追踪算法求解出影像的稀疏表示系数,最终通过高分辨影像字典与稀疏系数相乘得到融合影像。实验结果表明:本文提出的方法能很好地保持遥感影像的光谱信息和空间细节信息。