Towards an automated approach to map flooded areas from Sentinel-2 MSI data and soft integration of water spectral features

In this work we propose an approach for mapping flooded areas from Sentinel-2 MSI (Multispectral Instrument) data based on soft fuzzy integration of evidence scores derived from both band combinations (i.e. Spectral Indices - SIs) and components of the Hue, Saturation and Value (HSV) colour transformation. Evidence scores are integrated with Ordered Weighted Averaging (OWA) operators, which model user’s decision attitude varying smoothly between optimistic and pessimistic approach. Output is a map of global evidence degree showing the plausibility of being flooded for each pixel of the input Sentinel-2 (S2) image. Algorithm set up and validation were carried out with data over three sites in Italy where water surfaces are extracted from stable water bodies (lakes and rivers), natural hazard flooding, and irrigated paddy rice fields. Validation showed more than satisfactory accuracy for the OR-like OWA operators (F-score > 0.90) with performance slightly decreased (F-score < 0.75) over heterogeneous conditions (e.g. rice fields). The algorithm was applied with no changes and/or tuning to independent sites from the Copernicus Emergency Management Service (EMS) activations to simulate operational conditions. Over these sites, the proposed approach achieved greater, more consistent and robust mapping accuracy compared to traditional approaches based on the segmentation of single input features. Moreover, OWA operators offer an appealing way of combining and aggregating multiple information in decision making by modelling uncertainty in decision process.     

Towards a Deeper Understanding of Cartographic Text Visualisation: Assessment of User Preferences and Colour Influence

The main goal of this research is to investigate the influence of a map’s background colour on user preferences regarding labels’ typography, including their size, shape, orientation and texture. Four sets of backgrounds were tested: blank maps, grey scale, hot colours and cold colours. The foreground of these maps is populated with name labels, which are associated with point objects or areal objects. Bertin’s visual variables were applied to this set of name labels, both separately and in combination. User preferences of different typographic variations were registered and compared on the basis of different background colours using a one-way ANOVA. The results indicated that the typographic design of the map labels should not be adapted according to the map’s background colour.     

利用地理属性量表的色盲人群地图色彩设计研究

根据地图表达地理属性的量表性质,将地图设色方案分为定性设色、顺序设色和双向设色等3种方式。基于这3种地图设色方式的特点,根据红-绿色盲的光谱特性,设计了一系列实验地图,通过颜色辨识的心理学实验,分析了红-绿色盲的视觉特征,初步揭示出一些针对红-绿色盲人群使用的地图设色原则,为制作红-绿色盲人群使用的地图提供了有效的参考。     

ColorBrewer.org: An Online Tool for Selecting Colour Schemes for Maps

Abstract

Choosing effective colour schemes for thematic maps is surprisingly difficult. ColorBrewer is an online tool designed to take some of the guesswork out of this process by helping users select appropriate colour schemes for their specific mapping needs by considering: the number of data classes; the nature of their data (matched with sequential, diverging and qualitative schemes); and the end-use environment for the map (e.g., CRT, LCD, printed, projected, photocopied). ColorBrewer contains 'learn more' tutorials to help guide users, prompts them to test-drive colour schemes as both map and legend, and provides output in five colour specification systems.     

Investigating the Effectiveness of an Efficient Label Placement Method Using Eye Movement Data

Abstract

This paper focuses on improving the efficiency and effectiveness of dynamic and interactive maps in relation to the user. A label placement method with an improved algorithmic efficiency is presented. Since this algorithm has an influence on the actual placement of the name labels on the map, it is tested if this efficient algorithms also creates more effective maps: how well is the information processed by the user. We tested 30 participants while they were working on a dynamic and interactive map display. Their task was to locate geographical names on each of the presented maps. Their eye movements were registered together with the time at which a given label was found. The gathered data reveal no difference in the user’s response times, neither in the number and the duration of the fixations between both map designs. The results of this study show that the efficiency of label placement algorithms can be improved without disturbing the user’s cognitive map. Consequently, we created a more efficient map without affecting its effectiveness towards the user.     

地图色彩的配合

提出了GIS组件与演绎数据库推理功能相结合的一种集成方法．阐述了二者结合的优势，提供了一种用Horn子句表达空间查询规则的方法并结合具体实例进行详细描述。     

地图色彩的重要性及其应用

明确色彩在地图中的作用,更好地利用色彩的特性及其相互间的配色,提高地图的艺术性和使用价值。     

Spectral Schemes: Controversial Color Use on Maps

Cartographers have long discouraged the use of spectral, or rainbow, color schemes on thematic maps of quantitative geographic data, though such color use is common in GIS and scientific visualization. Recent research, however, has shown that spectral schemes are preferred and are interpreted accurately when used as multi-hue renditions of diverging schemes. Both spectral and diverging schemes can emphasize a critical point within a data range with light colors and emphasize both high and low extremes of the data with dark colors. Although spectral schemes include multiple saturated hues, they can be designed to accommodate map reading by people with red-green impaired color vision by skipping over the yellow-greens in the spectral sequence. Cartographers should encourage use of spectral color schemes for depicting diverging quantitative data, rather than insisting that these schemes should not be used.     

Map Libraries

Colour distortion, which is caused by the unavoidable mismatch between a map’s gamut and a device’s gamut, negatively affects the semiotic quality of maps. Cartographic communication often suffers from undesirable colour inconsistency. This method models cartographic colour reproduction as a constrained transform problem, namely, adapting a map’s gamut to fit a device’s gamut while preserving the semiotic quality. First, the characteristics of the map’s gamut are investigated by considering cartographic principles, and the fundamental concerns of preserving semiotic quality are proposed. Then, the self-organizing map method is introduced to iteratively optimize the cartographic colour reproduction. We implement this method and evaluate it based on a series of thematic maps. The results indicate that the proposed algorithm offers better results than two alternatives in terms of facilitating cartographic colour reproduction.     

多级栅格网络地图的组织与设计

多级栅格网络地图是当前网络地图的重要使用形式,通过对其海量栅格图像数据组织方式的研究,设计了图像转换的数学基础,根据当前常用网络地图的情况,分析了地图分级层数确定的方法,对各级地图表示内容进行了选择设计,并根据符号设计的主要方面,研究了基于视觉连续性的地图符号设计基本思路。     

Light mode and dark mode: Which one is suitable when using public-facing web maps? An experimental evaluation using eye-tracking

Dark maps, which are also called dark modes or dark themes, have gained popularity, but their usability has not been experimentally evaluated. This article presents a user experiment that uses eye-tracking to assess the usability of dark and light maps. Here, two widely used web maps, Google Maps and Gaode Maps, are selected at the street and city scales. Eight map-use tasks are designed and cover four operations (identify, compare, rank, and associate) with space-alone and attributes-in-space distinctions. Four pairs of map-use tasks (light-during-the-day, dark-during-the-day, dark-at-night, and light-at-night) are examined from three aspects: effectiveness, efficiency, and cognitive load. The results provide preliminary evidence that the light-during-the-day performance is generally the best in most cases, followed by the dark-at-night performance; the dark-during-the-day performance is the worst in all cases, followed by the light-at-night performance, which suggests that aligning the map design with the environment (i.e., lighting environment) is critical for better communication. The light-during-the-day performance is the best for space-alone tasks, and the dark-at-night performance is the best for attributes-in-space tasks. Our investigation also indicates that dark maps are far less favored in practice, which suggests that users' preference for using the dark mode of public-facing web maps needs to be shaped. Since light and dark maps are associated with photopic and scotopic vision, respectively, the results indicate the need for future studies on how to leverage scotopic vision to design better dark maps.     

The assessment of potential land use in the proposed irrigation command using Remote Sensing and GIS

Standard false colour composites (Std. FCC) on 1:50,000 scale was visually interpreted in conjunction with soil survey to prepare physiographic-soil map. Thirteen mapping units were delineated indicating soil association at family-level. Soil and land resource was evaluated for their land capability and irrigation suitability for its sustained use under irrigation. Land capability and land irrigability maps were generated as attribute map. These maps were integrated to suggest potential land use map. Current land use/land cover map prepared by visual analysis was spatially analysed in relation to potential land use to study potential changes in land use / land cover using GIS. The study reveals that 14.66% area has no limitation and can be brought to intensive agriculture by double cropping.     

Evaluating the Efficiency of Typographic Design: Gender and Expertise Variation

Abstract

Although the efficiency of label placement algorithms has been studied extensively, few studies considered the influence of the label designs on the efficiency of map readers. Labels are one of the most important elements on the map as they can provide more information than other symbols can. The design of the labels does have to stress the theme, shape and functionality of the associated objects, which results in a more efficient interpretation of the map content by the user. How the label designs can enhance the map readers’ efficiency (and thus the quality of the maps themselves) is the main objective of this study. A user study was conducted in which the participants were asked to locate a target label on a map. Different label designs were implemented across the trials. The participants’ reactions times were registered to measure their efficiency and statistically analysed using a one-way ANOVA. Two different users’ characteristics were considered: gender and expertise. Related to the size, shape, orientation and texture of the labels, a number of significant differences (P<0·05) and trends were located. Differences in efficiency between males and females, on the one hand, and between novices and experts, on the other hand, were also described statistically. Consequently, recommendations can be formulated regarding the design of labels in order to obtain more efficient maps, keeping in mind the map users’ characteristics.     

地图的集合模型(表达式)及比较应用初探

本文在分析和综合地图实质与内容的基础上,应用比较方法提出了点作为构成地图的“细胞”,并由此入手建立了点的一般集合表达式,指出表达式是点的定位基础信息、表示类属的性质特征信息、区别颜色的表象特征信息以及反映颜色浓淡的信息等6个变量的函数。然后推导了地图要素和最终的地图一般表达式。作为例子,文中运用这些表达式推证了各类点、各种地图要素及几种地图的表达式。 作者认为,依据这些表达式还可对作为传输信息工具的地图在人们认知过程中的作用和结果作进一步的探索。     

一种利用多时相TM影像分析地表植被变化的新方法--以敦煌地区绿洲植被变化分析为例

变化分析是多时相遥感影像的主要应用领域。以郭煌绿洲为例 ,探讨一种应用多时相TM影像进行地表植被变化分析的新方法。结果证明 ,用不同时相的NDVI影像进行彩色合成可以直观地反映地表植被的变化 ,而利用色彩变换得到的各分量可以对变化特点进行定量分析。其中色度反映变化类型 ,饱和度反映变化强度 ,而亮度图像则反映地表植被多年来的总体长势。除了直观和定量的特性之外 ,该方法还可以用于其它类型的变化分析 ,具有可扩展性     

一种利用多时相TM影像分析地表植被变化的新方法：——以敦煌地区绿洲植 …

变化分析是多时相遥感影像的主要应用领域。以敦煌绿洲为例,探讨一种应用多时相ＴＭ影像进行地表植被变化分析的新方法。结果证明,用不同时相的ＮＤＶＩ影像进行彩色合成可以直观地反映地表植被的变化,而利用色彩变换得到的各分量可以对变化特点进行定量分析。其中色度反映变化类型,饱和度反映变化强度,而亮度图像则反映地表植被多年来的总体长势。除了直观和定量的特性之外,该方法还可以用于其它类型的变化分析,具有可扩展性     

Designing Effective Bivariate Symbols: The Influence of Perceptual Grouping Processes

The purpose of this research was to empirically assess perceptual groupings of various combinations of symbol dimensions (e.g., graphic variables) used in designing bivariate map symbols. Perceptual grouping ability was assessed using the theory of selective attention, a construct first proposed in psychological research. Selective attention theory contends that one's ability to analyze a symbol's dimensions—such as color or size—is affected by other dimensions present in the same symbol. Symbol dimensions are described as either separable (capable of being attended to independently of other dimensions), integral (cannot be processed without interference from other dimensions), or configural (i.e., show characteristics of both integrality and separability, which may also form new, emergent properties). Without empirical evidence describing such interactions for various combinations of symbol dimensions, cartographers cannot truly evaluate the functionality of the symbols they use on maps. The symbol dimensions or graphic combinations chosen for this study were selected to incorporate a wide range of traditional cartographic symbolization, including line and lettering symbolization, areal shading, dot patterns, and point symbols. Combinations were examined in an abstract setting using a speeded classification task, which is the traditional means of studying selective attention. Subject reaction times provided an assessment of the levels of integrality, separability, and configurality. Results suggest that most symbol dimension combinations are either separable or exhibit evidence of asymmetrical dimensional interactions. Findings from this study will be integrated into subsequent experiments, the results of which will assist cartographers in the design of complex map symbols.     

从存量地形图到地理实体的自动化生产实践

目前全国多地都在积极推进新型基础测绘试点工作,其中,通过存量地形图数据生产地理实体是一项重要工作内容。本文介绍了地形图数据转换为基础地理实体的原理与主要流程,提出了一种从现有的DWG图和地形图数据库自动化生产地理实体的方法;基于iData数据工厂软件进行了实际数据的生产试验,验证了从地形图提取地理实体的可行性;总结了生产过程中的数据处理步骤和方法,统计了整个过程的自动化效率等详细信息,并分析了影响自动化效率的因素和提高自动化效率的方法,对从存量地形图数据生产地理实体的工作具有一定参考意义。     

后现代哲学视野下的微地图

在现代到后现代社会的转变过程中, 人类的信息传播模式进入自媒体时代, 在地图上表现为制图用户向大众或地图爱好者转移, 地图的精确性不高、表达方式多样化。微地图是其中的一种, 旨在改善传统地图表达和大众地理空间认知的矛盾, 改进自媒体时代地图用户的主观信息表达, 突破传统地图仅从有限、规范化的角度和维度对地理事物和现象进行表达的局限。首先, 针对微地图的3个特点, 在后现代哲学的视角下分析其产生的原因并给予解释; 然后, 利用认知语言学的体验人本观、原型范畴论和去中心论等后现代哲学方法论, 对传统地图的空间认知、信息分类、制图表达等基础问题进行批判性分析和重构, 形成具有后现代哲学特点的微地图概念框架;最后, 通过实验验证了微地图存在的可能性及其后现代属性。     

地理信息图库一体更新方法

地图与DLG数据的更新方式之间既有区别又有联系,在研究DLG数据增量更新及地图与DLG数据一体化管理的基础上,提出一种地理信息图库一体更新方法,以地理实体为单位进行几何、属性和地图表达信息组织管理,获取DLG数据的增量信息并对增量信息进行地图表达得到符号图形增量信息。最后通过试验数据验证了该方法的有效性,且其具有易于计算机实现、效率高、可扩展性强、适于地图与DLG数据一体化更新等优点。