A Design Of Dynamic Map Symbols Aiming At Multi-Feature Change Representation

The development of GIS data acquisition technology and application domains results in the spatiotemporal data is more and more collected and stored to describe the process of movement,change and updating.How to effectively display and visualize spatiotemporal data has become an interesting problem in this field.The visualization of spatiotemporal data can play an important role in revealing the characteristics of geographical events,reflecting the temporal and spatial pattern of the geographical process,and predicting the development trend of geoscience phenomena.Spatiotemporal data.visualization,in addition to correctly describing the characteristics and spatial structure of geographical entities,is particularly concerned with the simulation of spatial entities in the form of animation emphasizing the appearance,development,continuity,evolution and disappearance at the time dimension.Aiming at geo-event cognition and representation,the dynamic map is such a visualization method to show temporal changes of geographical phenomena based on multi-dimensional features.Compared with traditional static maps,dynamic map provides enhancement of the sense of continuity and obtainment of the whole process recognition of geographical phenomena and geographical events,while a static map is just a scan representation of event in time scale.As the foundation of dynamic map symbol,the visual symbol variables transfer semantic features and dynamic characteristics through proper parameter design,structure organization and spatial layout.The visual symbol variables play important roles in achieving the temporal function of dynamic map,including re-generating the past process,tracking the current changes and predicting the trend of future development.It is these functions that discovers the distribution pattern and evolution rules in both temporal and spatial fields.On the basis of the current development analysis of dynamic visualization,this thesis summarizes and classifies the dynamic geographical phenomena in the real world into appearance/disappearance,change(quality characteristics,quantitative characteristics)and movement(trajectory motion,boundary change).The study regards the change of spatiotemporal data under the multi-feature characteristics domain through common examples of multiple feature changes and illustrationsSecondly,this study examines the principle and method of visual variables,and analyze the visual variables of symbols(size,shape,color,direction,etc.)as well as the role and influence of extended dynamic variables(occurrence time duration,change rate,change order,rhythm)in designing dynamic symbols.Then the key frame concept in the animation technology is introduced into the dynamic symbol design,and the dynamic visual parameter is added to the change content.This thesis proposed the idea that the design of the dynamic symbol is actually the design of each frame change content.With the dynamic phenomenon classification system,the study builds the corresponding visualization rules involving the coupling maps between dynamic changes and dynamic symbols.Based on the computer animation technology,two visual examples are designed for two typical spatiotemporal change phenomena:population flow and the change of land vegetation coverage in Tibet.At last,the experiment is performed to verify whether the two examples can provide better understands to the movement process and characteristics of geographical phenomena,thus proving the symbol classification system and visualization rules are reasonable.