A Structure Recognition Technique in Contextual Generalisation of Buildings and Built-up Areas

Abstract

A structure recognition technique is presented that can be employed for contextual building and built-up area generalisation in medium-scale topographic maps. Owing to various spatial configurations, a contextual mechanism is necessary to achieve acceptable results in cartographic generalisation. Spatial structures are usually implicit in data, and advanced analysis and processing methods are required to detect them. This technique is based on auxiliary geometric data structures and spatial analysis methods. A case study is performed with a topographic data set, using an interface developed in an object-oriented geographic information system (O-O GIS). The proposed approach was found to assist and improve automation.     

用MAPS模式预报冰雹落区

文中详细分析了 1982～ 1998年发生在湖北省的冰雹过程 ,这些冰雹过程被归纳为槽前型和槽后型两类。两类过程的一个共同特点是过程发生前具有极强的位势不稳定。槽前型主要表现在中低空及地面为极强的增湿增暖 ,导致中低空能级升高 ,而中高层是相对干冷的区域或变化不是很大 ,这类过程的触发主要是由于西北槽中有短波槽扰动凌驾于不稳定区之上 ,一方面加大水平能量锋区 ,另一方面使得垂直不稳定度加大 ,进而触发对流。槽后型主要表现在中高层为极强的干冷平流 ,引起降温降湿 ,而低层有弱的增温增湿 ,这类过程的触发主要是西北气流中横槽转动和小槽沿脊前下滑 ,在中低层加大水平能量锋区 ,促进垂直不稳定能量的释放。因此将水平能量锋区ΔθseH/Δn和垂直不稳定ΔθseH/Δz之和作为冰雹判据 ,辅之以其它条件 ,在日常业务中 ,具有较高的预报准确率。利用研究结果 ,对武汉区域中心数值预报模式MAPS的积云对流参数化方案进行改进 ,即改进积云对流参数化中的稳定度条件。用改进后的MAPS模式对 1999～ 2 0 0 1年 3～ 5月的过程进行试报 ,结果表明 ,该模式对冰雹落区有一定的预报能力。     

‘This was different’: transferring climate mitigation knowledge practices south to south with the MAPS programme

This article is a case study of the Mitigation Action Plans and Scenarios programme (MAPS) which worked in climate change mitigation and development policy-making spaces in Brazil, Chile, Colombia, Peru and South Africa from 2010–2015. The MAPS programme was focused on achieving change in the commitment of southern decision makers to mitigate against climate change through government-mandated, stakeholder processes which generated evidence making a case for a low carbon transition. The article draws on reflective materials generated in the last year of the project. The value of MAPS was found in the well-tested data and evidence-driven scenario building; locally specific and country-driven processes; a culture of knowledge sharing through facilitated communities of practice; the role of professional facilitation in process design and in conducting stakeholder processes; shared experiences of working in the south, and particularly with cultural differences and conflict; and new ways of working south–south with each other, and with donors. These MAPS programme experiences stood in contrast to previous north–south knowledge sharing involvements. Theoretically, the article asks whether MAPS represents southern theory-making (after Connell, 2007). It concludes that through the action-oriented, facilitated co-production way of working on climate change in the south, MAPS represents an understanding of southern theory that challenges the orthodoxy of global knowledge production. MAPS emphasizes the need for theorizing in, and of, the south, and connecting policy and practices.

Key policy insights

• Climate change mitigation work in the south faces poorly resourced, fragmented, under-capacitated governance structures, often in conflicted settings.

• Given conflicted settings, skilled facilitation is an integral part of knowledge-making processes.

• Strong local communities of practice, who undertake learning-by-doing and are connected to ‘stubborn’ development realities, are also key to knowledge-making.

• Intentional co-production of data and evidence enable peer-to-peer learning and the trust-building which is vital to strong communities of practice.

     

Applications of Analytical Cartography

Several applications of analytical cartography are presented. They include terrain visibility (including visibility indices, viewsheds, and inter-visibility), map overlay (including solving round-off errors with C++ class libraries and computing polygon areas from incomplete information), mobility, and interpolation and approximation of curves and of terrain (including curves and surfaces in CAD/CAM, smoothing terrains with over-determined systems of equations, and drainage patterns). General themes become apparent, such as simplicity, robustness, and the tradeoff between different data types. Finally several future applications are discussed, such as the lossy compression of correlated layers, and just good enough computation when high precision is not justified.     

The Search for Boundaries on Maps: Color Processing and Map Pattern Effects

This paper presents a model which combines three of the parameters of the "Swiss manner" of relief representation with the Yoeli method of analytical hill-shading.

The model consists of various computational and graphic procedures that are intended to imitate by computer the complex hand-shading process. The first two procedures adjust the light source vertically and horizontally to the local relief forms. The adjustments avoid the disappearance of edges in unfavorable positions and exaggeration of others, and they utilize digitized data of the network of ridges and ravines. A third algorithm deals with "atmospheric perspective," the phenomenon of diminished value contrast in low lands and enhanced contrast in upper areas. This procedure also allows a general change in tonal value as a function of altitude. Other procedures deal with multicolor relief shading techniques, small-scale generalization, and selected reproduction problems.

Graphic output has been performed on a modified printer (IBM 1443) and a CRT raster recorder.     

The Politics of the Map in the Early Twentieth Century

Drawing on material from several countries, principally Britain, France, and the United States, this paper considers the politics of mapmaking in the years before, during, and immediately after World War I. Following a discussion of some noteworthy but hitherto overlooked mapping projects from the period around 1900, the paper examines the wartime production of maps as aids to geopolitical strategy in three Allied cities—London, Paris, and New York—with particular reference to the major geographical societies in these locations.     

Representing Complex Geographic Phenomena in GIS

Conventionally, spatial data models have been designed according to object- or field-based conceptualizations of reality. Conceptualization of complex geographic phenomena that have both object- and field-like properties, such as wildfire and precipitation, has not yet been incorporated into GIS data models. To this end, a new conceptual framework is proposed in this research for organizing data about such complex geographic phenomena in a GIS as a hierarchy of events, processes, and states. In this framework, discrete objects are used to show how events and processes progress in space and time, and fields are used to model how states of geographic themes vary in a space-time frame. Precipitation is used to demonstrate the construction and application of the proposed framework with digital precipitation data from April 15 to May 22, 1998, for the state of Oklahoma, U.S.A. With the proposed framework, two sets of algorithms have been developed. One set automatically assembles precipitation events and processes from the data and stores the precipitation data in the hierarchy of events, processes, and states, so that attributes about events, processes, and states are readily available for information query. The other set of algorithms computes information about the spatio-temporal behavior and interaction of events and processes. The proposed approach greatly enhances support for complex spatio-temporal queries on the behavior and relationships of events and processes.     

Interface Design for Geographic Visualization: Tools for Representing Reliability

Digital "softcopy" maps are becoming the norm—replacing static paper maps in applications from wayfinding to scientific research. As a result, the design of interface tools that allow users to manipulate map parameters effectively and efficiently is likely to become as fundamental to cartography as the design of maps themselves. This article presents some principles for the design of interfaces to geo-referenced data. These principles are summarized in a hierarchical approach to interface design with conceptual, operational, and implementational levels. This hierarchical approach leads designers from questions about the goals of the system and the users of that system to the creation of tools to accomplish those goals and interface controls that allow effective interaction with the tools. The article goes on to describe the application of these principles to a prototype geographic visualization system designed for exploration of spatial data sets and visualization of reliability of both data and data abstractions associated with environmental change. The prototype involves a synthesis of concepts and methods derived from cartography, scientific visualization, and exploratory data analysis into a system for exploratory spatial data analysis and spatial decision support.     

Maps and Mapping Technologies of the Persian Gulf War

Assessing the recent Persian Gulf War from a cartographic standpoint is now possible. Unlike in previous wars, which established new technologies for postwar cartographic exploitation, the gulf war is unique in having presented a proving ground for electronic cartographic technology. An analysis is given of map coverage of the war by the media, especially magazines and newspapers, and from a military perspective. From a cartographic standpoint, the winners in the war include hand-held Global Positioning System (GPS) technology, geographic information systems (GIS), workstation-based image processing and cartographic map-production systems, and radar imaging from aircraft. More fully exploiting and building on the success of these technologies in peacetime seems to be a clear mandate for academic and professional cartography.