Research On Automatic Construction Method And Application Of Cartogram

With the development of information and communications technologies(ICT),computer graphics,visualization methods,and with the widespread effect of the Internet,the ?non-traditional map?,which is no longer limited to the precision of traditional standard maps,becomes flourished.However,in spite of its prosperity,there are still many problems and challenges for applying these maps.In contrast,facing the challenges of new technologies and new demands,nowadays traditional cartography although with well-developed cartographical principles does not attract so much attention.Therefore,incorporating these ?non-traditional maps? into the systematical scientific framework of traditional cartographic representation methods is a necessity.On the one hand,the incorporation will help traditional cartography to overcome the aforementioned challenges in the digital era.On the other hand,it can extend the application range of these ?non-traditional maps?.This doctor thesis is dedicated to filling this gap and achieving a "win-win" situation for both traditional and non-traditional cartography.The thesis takes the most representative example of ?non-traditional maps?-Cartogram as the research topic,and study Cartogram theories,automatic generation methods and applications.The main works are as follows:1.A systematic review of the history of the Cartogram theories,methods and applications.The review starts from the origin of the Cartogram,and combines with the changes of the era and the technology waves.It helps researchers to grasp the future development and the trend of the Cartogram.On this basis,we summarize the problems and shortcomings during the development of Cartograms,including the incompleteness of the theoretical system,the incompleteness of the breadth and depth of the combination of construction methods and other disciplines,and the lack of Cartogram visualization for spatio-temporal data,etc.To address these problems,this study proposes research contents on the Cartogram theories,construction methods and applications.2.A research framework of the Cartogram theories and methods.We carry out research on four basic theoretical aspects on Cartogram visualization,generation and evaluation methods.First,starting from a variety of Chinese interpretations of the Cartogram,we explain essential features of the Cartogram,and propose a comprehensive Cartogram classification system.Based on this classification system,we then investigate Cartogram visualization methods and further discuss the relationship between Cartogram visualization and traditional map representation methods.Afterwards,we review different types of Cartogram construction methods,which lays the foundation for the optimization and innovation of the automatic generation method of the Cartogram as well as its wide applications.The evaluation methods and systems of Cartograms are also summarized.Finally,we use the diagram to show the structure of following chapters.3.A method of constructing a central time Cartogram based on moving least squares with constraints.Compared with previous research methods,this method solves three problems in the construction of central time Cartogram by proposing:(1)three design principles to keep the scale of the transformed map the same with its original map;(2)several constraints to adjust topological errors generated by the process of transformation based on Moving Least Squares(MLS);and(3)multiple visualization methods to represent the deformation of the time Cartogram.We take real train' timetable data from Beijing to other 307 selected cities in China in 2016 as a case study.The results show that our method is applicable and the visualizations depict the time distance relationship between Beijing and other cities from different perspectives.4.A method for constructing a continuous area Cartogram for Two or Multiple variables.This method improves and optimizes the classic algorithm of continuous area Cartograms — "the diffusion-based method for producing density equalizing maps".The progressive heuristics of the integration step is used to reduce the number of iterations,thus improving the efficiency of the algorithm.The first variable is visualized by the Cartogram and the second or more variables are visualized by interpolating location on a continuous area Cartogram and symbolizing then using more basic visual variables.We use the population density and bank/ATM distribution data(Bivariate)in Munich,the population density,kindergarten distribution,and scale data(Multivariate)in Augsburg as case studies.The experiment results show that compared with traditional methods,this method is more effective in finding some patterns of unbalanced distribution facilities,and can provide assistant references for urban planning and policy decision making.5.A time cartogram for the visual analysis of the dynamic spatial pattern of accessability.The dynamic time-Cartogram effectively visualizes spatiotemporal data and explores and digs some hidden rules and trends from three perspective views.We compare and analyze the differences between time space and geographic space at a certain time(horizontal comparison),and the changes of the horizontal comparison in a period of time,and the changes time pace in a period of time(vertical comparison).Then,we use the shortest railway travel time from Beijing to each selected city in 1996,2003,2009 and 2016 as a case study.The dynamic Cartograms are used to visualize the changes of time distances relationship between Beijing and other cities from 1996 to 2016 in multiple views.This provides a new visualization method for studying the evolution of temporal and spatial patterns and time-space compression in related fields such as urban geography,transportation geography and economic geography.6.Based on the above researches,a plug-in prototype of a Cartogram Extension is developed on the open source software platform QGIS.The plug-in has three functionalities,including automatic generation of the center-time Cartogram,automatic generation of continuous area Cartograms for multi-variables,and Cartogram animations.The development and implementation of the plug-in can further demonstrate our research results.Furthermore,since QGIS is an open source platform,the developed plug-in in this work helps the proposed research methods to be better applied and be verified in a wider range.