Spectrum cartography techniques,challenges, opportunities,and applications: A survey

The spectrum cartography finds applications in several areas such as cognitive radios, spectrum aware communications, machine-type communications, Internet of Things, connected vehicles, wireless sensor networks, and radio frequency management systems, etc. This paper presents a survey on state-of-the-art of spectrum cartography techniques for the construction of various radio environment maps (REMs). Following a brief overview on spectrum cartography, various techniques considered to construct the REMs such as channel gain map, power spectral density map, power map, spectrum map, power propagation map, radio frequency map, and interference map are reviewed. In this paper, we compare the performance of the different spectrum cartography methods in terms of mean absolute error, mean square error, normalized mean square error, and root mean square error. The information presented in this paper aims to serve as a practical reference guide for various spectrum cartography methods for constructing different REMs. Finally, some of the open issues and challenges for future research and development are discussed.     

The assessment of evolutionary algorithms for analyzing the positional accuracy and uncertainty of maps

Pre-geodetic maps are an important part of our cultural heritage and a potential source of information for historical studies. Historical cartography should be evaluated in terms of precision and uncertainty prior to their use in any application. In the last decade, the majority of papers that address multi-objective optimization employed the concept of Pareto optimality. The goal of Pareto-based multi-objective strategies is to generate a front (set) of nondominated solutions as an approximation to the true Pareto-optimal front. This article proposes a solution for the problems of multi-objective accuracy and uncertainty analysis of pre-geodetic maps using four Pareto-based multi-objective evolutionary algorithms: HVSEA, NSGAII, SPEAII and msPESA. “The Geographic Atlas of Spain (AGE)” by Tomas Lopez in 1804 provides the cartography for this study. The results obtained from the data collected from the kingdoms of Extremadura and Aragon, sheets of maps (54-55-56-57) and (70-71-72-73), respectively, demonstrate the advantages of these multi-objective approaches compared with classical methods. The results show that the removal of 8% of the towns it is possible to obtain improvements of approximately 30% for HVSEA, msPESA and NSGAII. The comparison of these algorithms indicates that the majority of nondominated solutions obtained by NSGAII dominate the solutions obtained by msPESA and HVSEA; however, msPESA and HVSEA obtain acceptable extreme solutions in some instances. The Pareto fronts based on multi-objective evolutionary algorithms (MOEAs) are a better alternative when the uncertainty of map analyzed is high or unknown. Consequently, Pareto-based multi-objective evolutionary algorithms establish new perspectives for analyzing the positional accuracy and uncertainty of maps.     

Generating Tile Maps

Tile maps are an important tool in thematic cartography with distinct qualities (and limitations) that distinguish them from better‐known techniques such as choropleths, cartograms and symbol maps. Specifically, tile maps display geographic regions as a grid of identical tiles so large regions do not dominate the viewer's attention and small regions are easily seen. Furthermore, complex data such as time series can be shown on each tile in a consistent format, and the grid layout facilitates comparisons across tiles. Whilst a small number of handcrafted tile maps have become popular, the time‐consuming process of creating new tile maps limits their wider use. To address this issue, we present an algorithm that generates a tile map of the specified type (e.g. square, hexagon, triangle) from raw shape data. Since the ‘best’ tile map depends on the specific geography visualized and the task to be performed, the algorithm generates and ranks multiple tile maps and allows the user to choose the most appropriate. The approach is demonstrated on a range of examples using a prototype browser‐based application.     

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.     

Localization of local soil classes in an arid region of Mexico,using satellite imagery

A map of local soil classes (LSCs) was used to make digital maps of soil classes using computer-assisted cartography. The objectives were to establish classes of the local soils of an arid locality; to determine their physical and chemical characteristics; to relate the content of clay (Cl), organic matter (OM) and electrical conductivity (EC) to the levels of reflectance from the classes of soil; and to obtain a digital map of classes of local soils using a supervised classification of the image and verify its precision. The map of LSCs was used as basis for generating information about the physical and chemical characteristics of soils. The information was related to digital levels of a Landsat 7 Enhanced Thematic Mapper Plus (ETM+) image, and a supervised classification was performed. The precision of the digital maps was verified. The results show that a map of LSCs can be used as basis for generating digital maps.     

The use of airborne remote sensing for benthic cartography: Advantages and reliability

Airborne remote sensing is a useful tool for the production of biocenosis maps. The use of an image processing system, integrating bathymetric data, makes it possible to considerably refine the charting, through a layer of water of variable thickness and quality. Other limiting factors may have an impact on the quality of results. The identification of these factors makes it possible to propose a scale of reliability. Four examples of aerial teledetection surveys provide the basis for ( i ) assessing the reliability of the maps, ( ii ) determining the reasons for this variation in reliability, and ( iii ) using the scale as a means for assessing the reliability of a given map. The factors used are such that the reliability scale could subsequently be applied to the cartography of other marine assemblages.     

Matching Images to Models for Registration and Object Detection via Clustering

A new technique is presented for matching image features to maps or models. The technique forms all possible pairs of image features and model features which match on the basis of local evidence alone. For each possible pair of matching features the parameters of an RST (rotation, scaling, and translation) transformation are derived. Clustering in the space of all possible RST parameter sets reveals a good global transformation which matches many image features to many model features. Results with a variety of data sets are presented which demonstrate that the technique does not require sophisticated feature detection and is robust with respect to changes of image orientation and content. Examples in both cartography and object detection are given.     

Cartographic name placement with Prolog

A major problem in computer cartography is how to place names on maps so they are clearly associated with the features they annotate, while avoiding overlap with other names and features. The logic programming language, Prolog, can be used to express the name-placement problem as a set of rules, referring primarily to the identification of free space, the generation of trial label positions, and the resolution of conflict between these positions. Cartographic features can be specified either explicitly as facts in the Prolog database or implicitly by presenting Prolog with the results of a prior analysis of potential label positions. The Prolog inference mechanism can then determine whether there is a combination of label positions that satisfies the rules of placement     

New approach based on ANN and RBF for analyzing the spatial distribution of electromagnetic field from an exposure standpoint

This paper shows the versatility of artificial neural networks (ANN) and radial basis functions (RBF) applied to electromagnetic analyses with Medium Wave samples. A new approach is given from an exposure point of view, analyzing field levels in wide areas. In particular supervised ANN are used to distinguish electromagnetic field areas, if levels are above or below a certain threshold. The novel application Electric-Frontier ANN (EF-ANN) allows us to compare the performances of different neural network topologies (linear and recurrent), and it also gives us the possibility to create maps via geographic information systems (GISs). Furthermore another designed application, Electric-Interpolation RBF (EI-RBF), is used to obtain interpolated maps of electric field levels in the environment under study, with excellent performances, and having the possibility of overlapping the results with the local cartography in GIS. The interest of these developed tools is to identify the areas where the levels are higher from an exposure standpoint, and to know how the distribution of levels is in a real environment, but using exclusively experimental samples which are more reliable than simulations.     

From real to metaphoric maps: Cartography as a visual language for organizing and sharing knowledge

In this paper we discuss about geographic representations as a basis for describing, organizing, accessing and understanding heterogeneous shared information on the web. Maps are popular on the web, because of the reference to space, the most important domain of human experience, the proliferation of location aware devices and services and the availability of a set of tools that enable an heterogeneous population of users to explore and even modify these representations.Metaphorical maps, representing concepts and relations of a specific knowledge domain with symbols taken from another well known and widely used domain, couple the benefits of cartographic representation with the power and intuitiveness of the metaphor, permitting the communication and sharing of such knowledge.We introduce a classification of maps based on antinomies between real and imaginary worlds, and between direct and metaphoric knowledge; we argue that cartography can be used as a visual language for organizing and sharing knowledge related to different semantic domains, supporting our arguments with examples. Finally, we define a set of functions and related data structures able to support a user in browsing cartographic representations using state-of-art tools and systems available on the web.     

地图制图的面向对象设计

在开发一个实际的GIS系统中，利用面向对象的思想，对地图制图对象进行了分类，从地图制图对象中抽象出20多个地图制图用的对象类，并充分利用面向对象的继承和多态性，实现了地图的制图输出、图层管理和文件存储等功能。文章对这些内容作了概要介绍。     

基于GIS的分布式实时协同制图系统的研究

由于Internet网络带宽限制等诸多方面的影响,基于GIS的分布式实时协同制图系统是较难实现的。采用复制式模型构造了一个基于GIS的分布式实时协同制图系统,并且采用动态数据格式作为各站点的交换数据,极大限度地战少了网络数据传输量,提高了系统的响应速度和稳定性,满足了协同制图系统对实时性的要求。     

Positional accuracy, positional uncertainty, and feature change detection in historical maps: Results of an experiment

The measurement and management of positional accuracy and positional uncertainty is especially problematic in historical cartography and Historical GIS applications, for at least two reasons: first, historical sources, and especially historical maps, generally carry a higher degree of positional inaccuracy and uncertainty compared to contemporary geographic databases; second, it is always difficult and often impossible to reliably measure the positional accuracy and positional uncertainty of the spatial attribute of historical data. As an added complication, the terms “inaccuracy” and “uncertainty” are often used as synonyms in the literature, with relatively little attention given to issues of uncertainty.In this article we propose a methodology for detecting the positional inaccuracy and positional uncertainty of measurements of urban change using historical maps at a very high spatial resolution (the building). A widely accepted and routinely employed method for detecting urban change, and spatial change in general, consists in overlaying two or more maps created at different dates, but the technique can lead to the formation of spurious changes—typically, sliver polygons—that are the product of misclassification error or map misalignment rather than actual modifications in land cover. In this paper we develop an algorithm to detect such spurious changes. More in general, we extend the discussion to examine the effects of positional uncertainty and positional inaccuracy in feature change detection analysis. The case-study is the city of Milan, Italy.     

基于ArcObjects组件式扩展的标准化地图制图实现*

基于ArcObjects进行COM扩展,针对具体应用开发符合国家和行业标准的地图制图关键组件,应用于ArcGIS及其二次开发软件中,实现标准化地图制图。实践证明该方法具有较高的灵活性和开放性。     

规划专题影像地图的概念重构与视觉融合设计

针对空间规划领域中专题影像地图的制图应用,对影像地图的分类体系、规划专题影像的制图框架及其中影像的功能角色等进行概念重构,并提出以"矢量与栅格、基础与专题"等关系的处理为核心,以色彩配置、符号构形、构图整饰为主体,以视觉变量协调为关键的视觉融合设计策略;示例证明能够有效指导对规划方案概念的系统表达。     

一种基于DCT系数特性的盲检水印算法*

利用分块DCT系数的周期特性,结合Z字形编码置乱技术和JPEG量化系数,提出了一种在分块DCT中频交流系数中嵌入有含义二值水印图像,以实现盲检测的水印方案。实验结果表明,该算法对图像剪切、JPEG有损压缩、中值滤波等攻击有很强的鲁棒性。     

The State of the Art in Cartograms

Cartograms combine statistical and geographical information in thematic maps, where areas of geographical regions (e.g., countries, states) are scaled in proportion to some statistic (e.g., population, income). Cartograms make it possible to gain insight into patterns and trends in the World around us and have been very popular visualizations for geo‐referenced data for over a century. This Work surveys cartogram research in visualization, cartography and geometry, covering a broad spectrum of different cartogram types: from the traditional rectangular and table cartograms, to Dorling and diffusion cartograms. A particular focus is the study of the major cartogram dimensions: statistical accuracy, geographical accuracy, and topological accuracy. We review the history of cartograms, describe the algorithms for generating them, and consider task taxonomies. We also review quantitative and qualitative evaluations, and we use these to arrive at design guidelines and research challenges.     

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.     

A computer system for handling digitized line data from geological maps

A system is described in which digitized line data, such as the boundaries shown on a geological map, are handled within existing software environments for data management and graphic display. Methods of preprocessing and interfacing are described, which were implemented with less software effort than would be needed for a specialized cartographic system. The methods may not be appropriate for high-precision production cartography, but provide a flexible method of meeting two objectives: in the short run, to extend existing computer plotting programs to include digitized lines; in the longer run, to gain experience with techniques for representing and describing geological maps in digital form. A structure of line-segment files and attribute data files is proving effective for these purposes. By separating the three functions of data recording, storage and display, which are combined inextricably in the traditional geological map, computer methods may provide increased flexibility for recording geological data observed in the field.