Design Of Dynamic Map Symbols For Geographical Scene Representation

As the saying goes,things change as time goes by.Since ancient times,people have been focusing on the natural evolution and human development of the geographical environment,seeking to discover the geographic features hidden in the long history through the visualization of geographic processes or phenomena.During the process,maps have been playing an important role.However,the content of maps in the past was simple,which mostly only reflected the real geographic environment and considered only geometric forms and spatial positions.It can only simply answer the question about "where and what".The representation of the former map was also limited by the single medium of paper.Therefore,the dynamic phenomena and events can only be expressed through conventional static symbols such as arrows and trend lines.The Internet age has created a new space – cyberspace.People’s attention is not limited to the real geographical space any longer,but to the events and phenomena occurring in cyberspace,which brings new challenges to map visualization.The representation of map symbols has shifted from a static,physical and single mode to a dynamic,scenic and multiple modes.To cope with this transformation,this paper starts from the dynamic visualization of geographic scenes and expands the connotation and extension of map symbol design: extend the dynamic map symbol design parametric system and establish the dynamic map symbol design paradigm,to realize multi-dimensional dynamic visualization for geographic scene representation.Also,the multi-scale visualization of symbols is studied.Firstly,we discuss and define the concept of the geographic scenes based on the map visualization,including the content and classification of geographic scenes,and complete the composition of geographic scenes from three perspectives: physical geographic elements,human geographic elements and cyberspace elements according to the thematic characteristics.After that,the term "dynamic" in cartography is analyzed under the new technology and a new definition of the dynamic map is defined.Secondly,on the basis of Bertin’s map symbol variables,the basic visual variables(graphics,position,color,light effect,materials and combination),dynamic visual variables(moment,duration,change rate,rhythm and synchronization),other perceptual variables(hearing and touch),and interaction control variables(symbol control and user roles)are reorganized to build a dynamic map symbol design variables system.Besides,the dynamic map symbol design principles including scene wholeness,dynamic subjectivity,symbol imageability and abstraction,and systematic orderliness are proposed in this paper as well.Based on the above research,a dynamic map symbol design paradigm is derived which consists of five steps: element analysis,geographic context,symbol design,interaction control,and scene configuration.The multi-scale representation of dynamic symbols for semantic,spatial and temporal levels is discussed with emphasis.Thirdly,using computer animations and particle systems as the implementation technology,we first analyze the dynamic characteristics and representation methods of physical geographic scenes elements,human geographic scenes elements and cyberspace scenes elements.Then some representative case symbols are selected respectively,including landslides and tornadoes in physical geographic scenes,POI and GDP in human geographic scenes,and file data Web Kit dependencies in cyberspace scenes and discuss the dynamic symbol design processes in detail.Also,the application of the LOD technique for multi-granularity symbol design is taken into account.Finally,taking the urban traffic scene as a case study,the multi-scale representation and scene configuration of dynamic symbols for thematic geographic scenes are studied.First of all,the scene composition elements are first analyzed to determine the dynamic symbol design elements on three scales: large,medium and small.Then,the Web browser side is selected as the scene display platform.AI and 3Ds Max software,Mapbox-GL and Three.js libraries are used to design the dynamic symbols,and the interactive control of a spatial-temporal dual domain is carried out to implement the large-scale display of weather,medium-scale display of local weather and vehicles,and small-scale display of noise environment.Thus,the multi-scale representation of geographical phenomena and traffic events in urban traffic scenes could be mapped through the method.In conclusion,the dynamic map symbol design method for geographic scene representation proposed in this paper is important to derive the functional transfer of maps from visual representation to visual analysis.In the visualization of geographic phenomena,geographic events and spatial processes,we could describe spatial characteristics,distribution patterns and evolutionary mechanisms through the maps,also digging deeper information content based on visual analysis.