一种纸质航海图水深注记表示的新方法

针对由多波束测深手段和由单波束测深及其他传统测深手段获得的水深数据长期并存这一实际,在分析现行的纸质航海图水深注记表示方法存在不足的基础上,提出一种基于字符颜色扩展的海图水深注记表示新方法,即以绿色水深注记表示由多波束测深手段获得的水深数据,黑色水深注记表示由单波束测深及其他传统测深手段获得的水深数据。初步分析表明,这是一种简单、易行的方法,可在纸质航海图上有效实现对两类不同来源、具有显著质量差别的水深数据的表示,能更好地满足航海人员通过纸质航海图上的水深注记直观、准确地认知、重建和利用海底地形信息的需要。     

土地利用图缩编中小图斑综合方法的改进

针对土地利用图缩编中小图斑综合方法存在的问题,提出了改进方法。引入数学模型使得最小上图图斑面积指标的确定具有针对性;同时将专家的知识和经验引入计算机制图,使得小图斑综合具有高效性和客观性。以太湖县二调成果1∶10万地形图制作为例,验证了该方法的可行性,具有一定的实用价值。     

街区式居民地多尺度表达不确定性分析

本文对街区式居民地多尺度表达的不确定性进行了分析,认为制图综合是街区式居民地多尺度表达存在不确定性的根本原因,并挖掘探讨了街区式居民地多尺度表达不确定性的本质及其分类。针对街区式居民地多尺度表达的各类不确定性,重点分析并确立了用街区式符号表达居民地时的不确定性类型及评价指标和方法。本文的研究成果可以应用于街区式居民地多尺度表达尺度转换方法优劣及产品不确定性的评估。     

基于决策树的机载LiDAR点云数据分类

本文采用基于决策树的人工智能方式,通过对点云数据分割、提取分割片轮廓,手动设置地物的约束条件来提取LiDAR点云中的地物。两组实验表明,本文的方法能够成功提取点云数据中的建筑物、车辆等地物;要提高精度,需增加点云密度,因此本文方法适用于较平坦的城镇地区。     

基于场景的不同类别不同粒度知识获取方法

本文提出基于场景的不同类别不同粒度知识获取方法,首先对此方法中场景、知识链、粒度的概念进行界定,从本质和整体上对该方法进行阐述,并通过实验证明此方法符合专题地图设计根本宗旨、能够有效获取不同类别不同粒度的知识,获取知识的结构属于高内聚、低耦合,具有易维护、易重复使用的优点。     

应用稀疏非负矩阵分解聚类实现高光谱影像波段的优化选择

针对高光谱影像数据高维性、高度相关性和冗余性等特点,提出应用稀疏非负矩阵分解聚类实现高光谱影像波段的优化选择。通过稀疏非负矩阵分解方法对高光谱影像进行稀疏化表示,同时顾及其可聚类的特性,在保留所选波段物理意义的基础上,得到波段选择后的高光谱影像降维数据。通过该方法对PHI-3高光谱影像进行波段选择的试验分析,应用聚类特征有效性分析波段聚类结果,并采用波段子集的信息量、相关性和可分性3类评价指标来验证方法的效果。最终,从运行效率和分类精度两方面证明了基于无监督聚类的稀疏非负矩阵分解对高光谱影像的波段选择的实用性。     

A new modelling method for evaluating external disturbing potential based on theory of unified representation of gravitational field

For a special use a new modelling method of evaluating external disturbing potential is presented in this paper. Being different from classical methods in physical geodesy this method is grounded upon the theory of unified representation of gravitational field. The models created in this way are particularly satisfactory for a high-speed computation of gravitational field in low altitude because they take account of topographic effects and have their kernel functions with simple structure and weak singularity.     

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.     

An experiment on the elevation accuracy improvement of photogrammetrically derived DEM

This paper focuses on a topic barely considered in the literature: how to improve the accuracy of a given Digital Elevation Model (DEM) irrespective of its lineage by identifying its most suspicious values (also denoted here as outliers). Methods tailored to a specific procedure and source (contour maps, remote sensing image, etc.) exist but they are not valid for other cases. This is a problem for both the producer and end user. The results of a comparison of two methods using six DEMs intended to be representative of different landscapes are reported here. Both methods have been applied to each DEM, producing a number of height candidates to be analysed. Assuming that all candidates are wrong, their elevations have been blindly replaced by interpolated heights, simulating the behaviour of the inexperienced user. The improved (or degraded) DEMs are then compared against the ground truth, and updated accuracy figures are calculated. The RMSE can diminish by 2 to 8% of the original value by changing less than 1% of the elevations in the dataset.     

Ad hoc shared‐ride trip planning by mobile geosensor networks

Recent developments in miniaturization of computing devices, in location‐sensing technology and in ubiquitous short‐range wireless networks enable new types of social behaviour. This paper investigates one novel application of these technologies, ad hoc inner‐urban shared‐ride trip planning: Transportation clients such as pedestrians are seeking ad hoc shared rides from transportation hosts such as private automobiles, buses, taxi cabs or trains. While centralized trip planners are challenged by assigning clients and hosts in an ad hoc manner, in particular for non‐scheduled hosts, we consider the transportation network as a mobile geosensor network of agents that interact locally by short‐range communication and heuristic wayfinding strategies. This approach is not only fully scalable; we can also demonstrate that with short‐range communication, and hence, incomplete transportation network knowledge a system still can deliver near‐to‐optimal trips.