应用最优化订正法制作长江上游面雨量预报

利用最优化订正法，通过对MAPS数值降水预报进行订正，制作长江上游六大流域短期面雨量预报。2002年6－10月业务试验表明，长江上游六大流域平均的常规降水面雨量预报准确率比MAPS高19％左右，强降水天气过程的击中率为48％左右，取得了较好的效果。     

World Maps With Natural Boundaries

The graticule of meridians and parallels is a largely artificial type of map boundary that can detract from the display of irregular features such as oceans. Such natural boundaries as shorelines may be used instead as the boundary of world maps. The principle of natural boundaries has been applied to several examples of equal-area or conformal world ocean maps with single or multiple lobes. By careful selection of the poles and centers, these maps can show both oceans and continents in their entirety on a single map.     

Animated Maps of Aggregate Data: Conceptual and Practical Problems

Predictions of the 1960s about the computer's potential to change cartography are finally being fulfilled. Dynamic maps for vehicle navigation, interactive cartographic/statistical tools, and map animation are being investigated actively. As these new environments for mapping become available, we must reevaluate past questions about transformations from reality to data and data to map. In this paper, we consider these transformation questions in the context of statistical map animation. The issues discussed were raised in producing a “map movie” depicting the spread of acquired immune deficiency syndrome (AIDS) over time. Jenks' data model concept is used as the basis for a typology of data models representing phenomena typically depicted by enumeration unit data. The typology is then used to evaluate symbolization decisions for AIDS incidence maps. Implications for symbol selection imposed by dynamic rather than static maps are considered, as are technical issues involved in producing the animation on a microcomputer platform. A hybrid symbolization method that we have termed the “chorodot” is suggested as a way to meet the constraints on symbolization imposed by animation and to represent the appropriate data model for AIDS incidence.     

Integrating Sketch Maps with GIS to Explore Fear of Crime in the Urban Environment: A Review of the Past and Prospects for the Future

Understanding the spatial dimension of fear of crime in the urban environment is important to understanding behaviors in response to this concern. Making this connection between perception and action has long been a goal of scholars in the social and health sciences, though this complex relationship has yet to be fully elucidated. Specifically, in studies on fear of crime and its influence on behavior, a variety of definitions and methods have been employed. This situation has yielded insights, as well as inconsistencies. In the past decade, Geographic Information Systems (GIS) has been added to this methodological mix, though it too has contributed limited understanding of the environmental perception-behavior nexus. During this time, some scholars have integrated a traditional technique for accessing environmental perception, the sketch map, with this newer technology. This article provides a review and critical assessment of the way GIS has been used to understand fear of crime, specifically through the integration of sketch maps. This focus is framed by an overview of substantive and methodological concerns and concludes with a discussion of continued research needs. As behavioral responses to fear of crime are acknowledged to impact physical and mental health and overall well-being, in addition to the viability of neighborhoods, research in this area will continue apace. However, for integration of sketch maps in GIS to be a valuable methodological contributor to this line of inquiry, users of the approach must understand its complexities. This article outlines these issues so that they may be considered in future research and may improve the ability for this approach to yield new understanding of fear of crime.     

Mapping Population Distribution in the Urban Environment: The Cadastral-based Expert Dasymetric System (CEDS)

This paper discusses the importance of determining an accurate depiction of total population and specific sub-population distribution for urban areas in order to develop an improved "denominator," which would enable the calculation of more correct rates in GIS analyses involving public health, crime, and urban environmental planning. Rather than using data aggregated by arbitrary administrative boundaries such as census tracts, we use dasymetric mapping, an areal interpolation method using ancillary information to delineate areas of homogeneous values. We review previous dasymetric mapping techniques (which often use remotely sensed land-cover data) and contrast them with our technique, Cadastral-based Expert Dasymetric System (CEDS), which is particularly suitable for urban areas. The CEDS method uses specific cadastral data, land-use filters, modeling by expert system routines, and validation against various census enumeration units and other data. The CEDS dasymetric mapping technique is presented through a case study of asthma hospitalizations in the Bronx, New York City, in relation to proximity buffers constructed around major sources of air pollution. The case study shows the impact that a more accurate estimation of population distribution has on a current environmental justice and health disparities research project, and the potential of CEDS for other GIS applications.     

Constraints as Means of Controlling Usage of Geovirtual Environments

In this paper a concept for controlling the usage of geovirtual environments by means of constraints is developed. Constraints serve to improve the usability of geovirtual environments by guarding the navigation and interaction processes of users. In addition, they facilitate the implementation of Digital Rights Management for geovirtual environments. The presented approach distinguishes spatial constraints, structural constraints, and redistribution constraints. Several types of spatial constraints have been identified for navigation in geovirtual environments. To demonstrate their applications, this paper reports on using constraints in virtual 3D city models.     

Assessment of Simulated Cognitive Maps: The Influence of Prior Knowledge from Cartographic Maps

Real cognitive maps encoded by humans are difficult to study using experimental methods because they are a product of complex processes whose content and timing cannot easily be known or controlled. This paper assesses the value of using neural network model simulations for investigating cognitive maps. The study simulated the learning of mapped city locations in South Carolina from reference sites in the three primary regions of the state using Kohonen self-organizing maps. The learning performances of models were considered based on available prior knowledge. Bi-dimensional regression analyses were used to assess the congruity of the simulated cognitive maps with a cartographic map and with sketch maps produced by human subjects. Error analyses indicated differences between central and peripheral reference sites. The cities known by subjects living at a central location were more evenly distributed in space and associated with significantly smaller errors. Models that learned combined state boundary and interstate highway information as prior knowledge or simultaneously with city locations consistently produced the best simulation results. The results indicated simulated cognitive maps could be used effectively to study the acquisition of spatial knowledge.     

A New Method for the Specification of Geographic Footprints in Digital Gazetteers

This paper presents the strategy used to add neighborhood names and footprints to the Los Angeles Digital Gazetteer. The gazetteer database currently contains 4,500 features and is needed to: (1) facilitate the specification of geographic footprints in the Qualified Dublin Core metadata records that are used to describe digital assets; and (2) support the search for and retrieval of selected objects based on location, time, format, and/or keyword. The role of the digital gazetteer and a new browser which will offer the library patron a web-based query form with an interactive map is explained. The interface can be used to draw a query on a map, and it provides a series of pull down menus that can be used to specify time periods, formats, collections, and key words of interest. A new method for specifying neighborhood footprints in the digital gazetteer is described in some detail, and opportunities are highlighted for generalizing the method to help with search and retrieval using the map browser.     

Effects of Animations in Zooming and Panning Operations on Web maps: A Web-based Experiment

Abstract

The presentation of graphics and maps on the Internet has led to the development of several new techniques. The use of dynamics and animations in maps has increased, and new types of applications are emerging frequently. Recently, several map providers on the web have introduced zooming in maps as an animated operation. In this paper, we look closer into how the animated zoom is perceived by participants in an experiment, and compare these observations with a corresponding test where the map scale is changed in more abrupt steps. The results indicate significant preference for the animated zoom. The experiment itself is carried out through the World Wide Web and all the participants made their contribution from their own computers.     

Unclassed Animated Choropleth Maps

Abstract

The potential of unclassed animated choropleth maps as a solution to false patterns of geographic change arising from data classification is investigated. Old concerns about unclassed choropleth maps may be mitigated through map interactivity that offers four advantages over traditional data legends, and previous insights from testing static choropleth maps do not necessarily translate to animated cartography. Data from user testing revealed unclassed animated choropleth maps neither help nor hurt the ability of map readers to understand patterns of geographic change. However, the unclassed map (1) appeared 'less jumpy' to participants and was perceived to run at a slower pace (despite running at the same number of frames per second), and (2) subtle geographic shifts (e.g., seasonal unemployment cycles) were more readily noticed on the unclassed maps. Preliminary results also suggest classed data emphasise stability over time – while their unclassed counterparts improve our ability to see changes. This paper also outlines animated simultaneous contrast as a new perceptual issue in the creation of animated choropleth maps.