The p-Median problem (PMP) is one of the most widely applied location problems in urban and regional planning to support spatial decision-making. As an NP-hard problem, the PMP remains challenging to solve optimally, especially for large-sized problems. This research focuses on developing geocomputational approaches to improve the effectiveness and efficiency of solving the PMP. This research also examines existing PMP methods applied to choropleth mapping and proposes a new approach to address issues associated with uncertainty. Chapter 2 introduces a new algorithm that solves the PMP more effectively. In this chapter, a method called the spatial-knowledge enhanced Teitz and Bart heuristic (STB) is proposed to improve the classic Teitz and Bart (TB) heuristic.. The STB heuristic prioritizes candidate facility sites to be examined in the solution set based on the spatial distribution of demand and candidate facility sites. Tests based on a range of PMPs demonstrate the effectiveness of the STB heuristic. Chapter 3 provides a high performance computing (HPC) based heuristic, Random Sampling and Spatial Voting (RSSV), to solve large PMPs. Instead of solving a large-sized PMP directly, RSSV solves multiple sub-PMPs with each sub-PMP containing a subset of facility and demand sites. Combining all the sub-PMP solutions, a spatial voting strategy is introduced to select candidate facility sites to construct a PMP for obtaining the final problem solution. The RSSV algorithm is well-suited to the parallel structure of the HPC platform. Tests with the BIRCH dataset show that RSSV provides high-quality solutions and reduces computing time significantly. Tests also demonstrate the dynamic scalability of the algorithm; it can start with a small amount of computing resources and scale up or down when the availability of computing resources changes. Chapter 4 provides a new classification scheme to draw choropleth maps when data contain uncertainty. Considering that units in the same class on a choropleth map are assigned the same color or pattern, the new approach assumes the existence of a representative value for each class. A maximum likelihood estimation (MLE) based approach is developed to determine class breaks so that the overall within-class deviation is minimized while considering uncertainty. Different methods, including mixed integer programming, dynamic programming, and an interchange heuristic, are developed to solve the new classification problem. The proposed mapping approach is then applied to map two American Community Survey datasets. The effectiveness of the new approach is demonstrated, and the linkage of the approach with the PMP method and the Jenks Natural Breaks is discussed.

abstract: Choropleth maps are a common form of online cartographic visualization. They reveal patterns in spatial distributions of a variable by associating colors with data values measured at areal units. Although this capability of pattern revelation has popularized the use of choropleth maps, existing methods for their online delivery are limited in supporting dynamic map generation from large areal data. This limitation has become increasingly problematic in online choropleth mapping as access to small area statistics, such as high-resolution census data and real-time aggregates of geospatial data streams, has never been easier due to advances in geospatial web technologies. The current literature shows that the challenge of large areal data can be mitigated through tiled maps where pre-processed map data are hierarchically partitioned into tiny rectangular images or map chunks for efficient data transmission. Various approaches have emerged lately to enable this tile-based choropleth mapping, yet little empirical evidence exists on their ability to handle spatial data with large numbers of areal units, thus complicating technical decision making in the development of online choropleth mapping applications. To fill this knowledge gap, this dissertation study conducts a scalability evaluation of three tile-based methods discussed in the literature: raster, scalable vector graphics (SVG), and HTML5 Canvas. For the evaluation, the study develops two test applications, generates map tiles from five different boundaries of the United States, and measures the response times of the applications under multiple test operations. While specific to the experimental setups of the study, the evaluation results show that the raster method scales better across various types of user interaction than the other methods. Empirical evidence also points to the superior scalability of Canvas to SVG in dynamic rendering of vector tiles, but not necessarily for partial updates of the tiles. These findings indicate that the raster method is better suited for dynamic choropleth rendering from large areal data, while Canvas would be more suitable than SVG when such rendering frequently involves complete updates of vector shapes. / Dissertation/Thesis / Ph.D. Geography 2013

<p>The population of Sweden is ageing as in almost every European country. Improved medical progresses and treatment options lead to a decreasing mortality at older ages, increasing life expectance and an advanced health of the elderly. Due to these improvements and the so called ‘baby- boomers’, a great number of persons born in the 1940s that will reach retirement age the coming years, their total number will increase strongly in the near future all over Sweden. To enable these elderly to live a normal, active and independent life as long as possible activities, services and special housing with improved accessibility and meeting places for elderly has to be provided. Thus, for local authorities it is essential to know the actual and favoured living conditions as well as environments of elderly. This study aims therefore to investigate the characteristic of preferred residential neighbourhoods of the elderly in the city of Norrköping. The demographic, social and crime situation was examined for the districts of the city using several methods from both Statistics and GIS. Statistical methods included classifications, indexes or indicators and bivariate correlations. A model was developed to combine demographic and social data to characterise districts. GIS was to a major extent used as a visualisation tool. Choropleth mapping and Kernel density estimations were used to illustrate distribution of elderly and crime. Preliminary global statistical tests were used to verify clustering in the crime data set. An accessibility analysis was conducted with the help of the network analyst tool. Results indicate that districts experiencing the highest total numbers and proportion of elderly are very distributed throughout the city of Norrköping. They are, with some exceptions, characterised by lower social status. Four districts of the city show considerable evidences of demographic ageing, experiencing a population pyramid formed like an urn. Beside districts where elderly constitute a bigger proportion of the population, they tend to live in districts characterised by a relatively high proportion of young adults aged between 20 and 29. Crime analyses have shown crime clusters in different parts of the city. A high proportion of elderly faces a high crime level in the districts Gamla staden, Nordantill and Hageby. However, it has been proved that only some hot spots of crime within these areas contribute to the high crime level. Districts such as Skarphagen, Såpkullen, Smedby and Linö, all (except Såpkullen) situated on the outskirts of the city, hold high or middle elderly and a low crime level. Accessibility analyses have shown that elderly aged over 80 do not live significant closer to health centres and the public transport stops compared to the age groups 20 – 65 and inhabitants aged between 65 and 79.</p>

The population of Sweden is ageing as in almost every European country. Improved medical progresses and treatment options lead to a decreasing mortality at older ages, increasing life expectance and an advanced health of the elderly. Due to these improvements and the so called ‘baby- boomers’, a great number of persons born in the 1940s that will reach retirement age the coming years, their total number will increase strongly in the near future all over Sweden. To enable these elderly to live a normal, active and independent life as long as possible activities, services and special housing with improved accessibility and meeting places for elderly has to be provided. Thus, for local authorities it is essential to know the actual and favoured living conditions as well as environments of elderly. This study aims therefore to investigate the characteristic of preferred residential neighbourhoods of the elderly in the city of Norrköping. The demographic, social and crime situation was examined for the districts of the city using several methods from both Statistics and GIS. Statistical methods included classifications, indexes or indicators and bivariate correlations. A model was developed to combine demographic and social data to characterise districts. GIS was to a major extent used as a visualisation tool. Choropleth mapping and Kernel density estimations were used to illustrate distribution of elderly and crime. Preliminary global statistical tests were used to verify clustering in the crime data set. An accessibility analysis was conducted with the help of the network analyst tool. Results indicate that districts experiencing the highest total numbers and proportion of elderly are very distributed throughout the city of Norrköping. They are, with some exceptions, characterised by lower social status. Four districts of the city show considerable evidences of demographic ageing, experiencing a population pyramid formed like an urn. Beside districts where elderly constitute a bigger proportion of the population, they tend to live in districts characterised by a relatively high proportion of young adults aged between 20 and 29. Crime analyses have shown crime clusters in different parts of the city. A high proportion of elderly faces a high crime level in the districts Gamla staden, Nordantill and Hageby. However, it has been proved that only some hot spots of crime within these areas contribute to the high crime level. Districts such as Skarphagen, Såpkullen, Smedby and Linö, all (except Såpkullen) situated on the outskirts of the city, hold high or middle elderly and a low crime level. Accessibility analyses have shown that elderly aged over 80 do not live significant closer to health centres and the public transport stops compared to the age groups 20 – 65 and inhabitants aged between 65 and 79.

The thesis focuses on one of the map skills - map interpretation. The aim of the thesis is to characterize the process of solving tasks aimed at the interpretation of two types of thematic maps (chloropleth mapping and area-shading mapping) by students of final year high school and first year university. In the theoretical part of the thesis, map skills - reading, analysis, interpretation and map making - are characterized. Further, the concept of mapwork strategies is defined and the basis for determining these strategies is described. The thesis also discusses the application of eye-tracking technology in research aimed at investigating map skills. The characteristics of the two thematic cartography methods used in the experiment within this thesis - chloropleth mapping and area-shading mapping, are also described. The experiment conducted within this thesis was carried out on a sample of 19 participants. These participants completed, using eye-tracking technology, a didactic test containing tasks on the interpretation of thematic maps. Subsequently, they completed a questionnaire in which they evaluated e.g. the difficulty of the test or the way they handled the individual stimulus elements. They also gave a semi-structured interview in which they looked back on the test and described their...