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《制图学和地理信息科学》2013,40(2):129-138
We examine some benefits of using the medial axis as a centerline for rivers and lakes. One benefit, automatic centerline generation, has been used for many years. We show that additional benefits can be derived from the geometric relationships between the medial axis and the riverbanks or lakeshores. These include area estimates, association of centerline analysis to banks, and definition of opposite for riverbanks. We also report on our experience at approximating the medial axis with a Voronoi diagram of point sites. 相似文献
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《制图学和地理信息科学》2013,40(2):77-102
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. 相似文献
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