Effective Graphic Features for Multivariate Symbol Mapping

Abstract

Various patterns of cartographic multivariate symbols (MSs) have been developed to work efficiently with objective symbol mapping. One such MS pattern is composed of a graph that uses spatial data to represent statistical data. A preliminary study revealed major problems with users’ perceptions and understanding of the symbol. These problems present obstacles to the presentation objectives. We are therefore interested in studying the human factors that contribute to the visual perception of graph symbols. We predict that the graph symbols currently in use are too complex for viewers to fully understand what they are intended to represent. This research aims to study the mechanisms and behaviours of human visual perception that are necessary to understand cartography MSs and to determine a more effective prototype symbol that presents and conveys information to viewers more efficiently. The prototype design is based on a basic cartographic symbol and includes the characteristics and properties of the original patterns of graph symbols via a study of their pros and cons. Graphic structures and properties were modified to create a more effective symbol.     

Impact of feature selection on the accuracy and spatial uncertainty of per-field crop classification using Support Vector Machines

Crop mapping is one major component of agricultural resource monitoring using remote sensing. Yield or water demand modeling requires that both, the total surface that is cultivated and the accurate distribution of crops, respectively is known. Map quality is crucial and influences the model outputs. Although the use of multi-spectral time series data in crop mapping has been acknowledged, the potentially high dimensionality of the input data remains an issue. In this study Support Vector Machines (SVM) are used for crop classification in irrigated landscapes at the object-level. Input to the classifications is 71 multi-seasonal spectral and geostatistical features computed from RapidEye time series. The random forest (RF) feature importance score was used to select a subset of features that achieved optimal accuracies. The relationship between the hard result accuracy and the soft output from the SVM is investigated by employing two measures of uncertainty, the maximum a posteriori probability and the alpha quadratic entropy. Specifically the effect of feature selection on map uncertainty is investigated by looking at the soft outputs of the SVM, in addition to classical accuracy metrics. Overall the SVMs applied to the reduced feature subspaces that were composed of the most informative multi-seasonal features led to a clear increase in classification accuracy up to 4.3%, and to a significant decline in thematic uncertainty. SVM was shown to be affected by feature space size and could benefit from RF-based feature selection. Uncertainty measures from SVM are an informative source of information on the spatial distribution of error in the crop maps.     

基于ArcGIS的矿山资源遥感监测符号库的建立

在矿产资源开发多目标遥感调查与监测项目中,ArcGIS自带的符号库已远不能满足专业需求,须建立新的专业符号库。本文研究ArcGIS符号管理器(Style Manager)及Font Creator 5.0字体编辑器制作符号的方法。针对某矿山区域,建立了矿产资源开发多目标遥感调查与监测专题符号库,并基于ArcGIS Engine和VB.net编程方法,实现地图点、线、面要素的自动符号化显示与管理功能。     

国外地图符号表示差异研究

列举不同国家地图符号表示差异的基础上,确定从视觉变量理论的角度出发对地图符号表示差异进行研究.以色彩视觉变量为例,分析不同国家在色彩使用上的差异是由不同的文化观念造成的.在此基础上探究不同国家地图符号上的差异来源于地图设计者的空间认知能力,即认知结构上的差异.文中设计了地图符号对照表,以此建立国外地图符号与我国符号的对应关系,易于操作,直观明了.     

位置地图情境分类分级与切换研究

情境建模是拓展移动地图应用,提供个性化位置服务的有效工具。本文鉴于目前的情境模型存在情境类型区分不清晰、不同情境之间难以切换的问题。首先,剖析了活动与情境分类分级的联系,提出了一种基于活动分层的位置地图情境分类分级方法;然后,在此基础上,研究了情境切换的方式与方法,建立了位置地图情境切换方式与方法之间的对应关系;最后,以用户去机场登机为例,进行了实际验证。     

The NASA environment remote sensing analysis facility (ERSAF) support for space shuttle earth observations

Abstract

A major concept in urban geography deals with determining the spheres of influence for urban centers. This paper describes an instructional module used in two different geography courses showing students how a model might be developed to measure spheres of influence for multiple urban centers within a given region. A geographic information system (GIS) is employed throughout the development of the model. This module is incorporated into a traditional undergraduate urban geography course and a beginning GIS course. The software packages used are MapViewer and Grapher. The region is the Mississippi Lowlands with five urban centers: New Orlenas, Memphis, Little Rock, Jackson, and Baton Rouge. Keywords: GIS, spheres of influence, MapViewer, urban geography.     

A bevy of area-preserving transforms for map projection designers

ABSTRACT

Sometimes map projection designers need to create equal-area projections to best fill the projections’ purposes. However, unlike for conformal projections, few transformations have been described that can be applied to equal-area projections to develop new equal-area projections. Here, I survey area-preserving transformations, giving examples of their applications and proposing an efficient way of deploying an equal-area system for raster-based Web mapping. Together, these transformations provide a toolbox for the map projection designer working in the area-preserving domain.     

Visual clutter reduction in zoomable proportional point symbol maps

ABSTRACT

Proportional point symbols are commonly used in map displays. However, when such displays are zoomed out, the available map space shrinks and consequently symbols overlap and the display suffers from visual clutter. Therefore, solutions are needed to reduce visual clutter in zoomable map displays that contain proportional point symbols. The authors add to the body of knowledge through the investigation of the performance of three solutions: aggregation of unit areas, the displacement of overlapping symbols, and modified symbolization; four variations of modified symbolization are examined in detail. The original study begins with a consideration of the strengths and weaknesses of the solutions, with an emphasis on information loss. Thereafter, user sessions with 165 participants are arranged to gain empirical evidence of the performance of the solutions. The results reveal that although participants zoom out the map to zoom levels that implement visual clutter reduction techniques, they tend to zoom in the map and pan it to examine specific areas. Moreover, they willingly use the map with aggregated unit areas in cases when the solution facilitates task accomplishment. A certain amount of skepticism attaches to the solution that displaces overlapping symbols.     

基层矿政管理系统建设模式研究

基于当前矿政管理系统存在问题与SuperMap GIS产品特性,提出将面向基层矿政管理为核心的矿政系统建设思路;利用面向Web服务方式实现业务系统间的数据流与业务流的无缝集成,解决了现有矿政业务系统间由于数据结构及业务流程的差异无法实现直接集成与共享问题。本文提出的系统建设思路在以下方面做出有益尝试,包括矿政管理业务数据采集获取、一张图综合应用、矿政业务应用、综合监管及上下级业务数据交换等问题,对于基层矿政管理建设具有示范意义。     

深度挖掘“天地图”的教育功能

“天地图”是国家测绘地理信息局主导建设的国家地理信息公共服务平台和地理信息综合服务网站,可向社会公众提供权威、可信、统一的在线地理信息服务。同时,在其他领域的作用和价值也同样不可小视,尤其是地理知识教育、国家版图教育、爱国主义教育、红色教育等教育功能的应用、服务具有广阔的发展空间。文章以“天地图”现有应用板块“伟业宏图”为例,探讨深度挖掘“天地图”的高校马克思主义红色教育功能的应用价值及策略。