Research On Wall Map Visualization Method Of Multivariable Spatio-temporal Line Features

Line elements are the objective things,phenomena,or trajectories that reflect the linearity in the geographical world.Visualization of line features is an important visualization method in spatial information visualization.With the development of data acquisition technology,the demand for visual expression of multivariate data is increasing.The visualization method of line elements in traditional cartography is difficult to meet the requirements of multivariate spatial-temporal mapping.Therefore,a new visualization method for multivariate line elements needs to be selected.The existing multivariate line elements visualization method directly visualizes more detail features,such as space-time path,space-time cubes,etc.;aggregation or feature visualization takes into account overall characteristics such as density maps,flow graphs,and so on.A visualization method that supports both overview and detail line elements is lack.The overview plus detail method is a visual requirement that can concertrate on detail and overview.In response to the above problems,the concept of "wall map" was first proposed by Cheng T et al.to reflect the traffic delay congestion situation.It is a metaphorical visualization method that can linearize the geography.The thing or trajectory represented is analogous to the wall in our life.It expresses various attributes through the expression of wall unit(surface,height,thickness,wall top,etc.),and is a visualization method that can support the overview plus detail.However,the existing wall map visualization method lacks systematic classification,and the construction method of the wall map is not perfect.Besides,the researches on visualization usability of the wall map are lack.Therefore,the rational use of wall map which support visualization of the overview and details multivariate line elements is a scientific problem that needs to be solved in the paper.In order to solve the problems existing in multivariate line feature visualization methods,this paper takes the multivariate line elements visualization method as the entry point,constructs a wall map visualization model based on principles of visual coding and visualization,defines a wall map visualization method,and finally designs three comparison experiments between wall map and time-series map,wall map and map,different types of maps with wall map to verify the usability of wall maps.The main research contents and achievements are as follows:(1)The wall map model combined with static visual variable expression.The characteristics of visual variables can be analyzed from three aspects of the existing static visual variable characteristics,static visual variable coding principles,and visual design principles.On this basis,a classification system for wall map was constructed.Starting from the basic elements of wall map,the composition and arrangement of different elements were designed.Finally,the dimensions of the map space(two-dimensional,three-dimensional)and the dimensions of the wall map(two-dimensional and three-dimensional)are jointly discussed,and the expression and scope of the different dimensions of the wall map in different dimensions of the map space are summarized.(2)The method of wall map construction.The paper construct wall map visualization method based on wall map visualization model.Through two specific cases of multivariate line elements(typhoon trajectory data,floating car trajectory data),referring to a wall map classification system,selecting a suitable variable mapping method,constructing a wall map model,and finally realizing the visualization of the wall map.(3)The evaluation of wall map visualization usability.On the basis of the visual construction method of wall map,in order to further verify the usability of the wall map.The paper designs corresponding wall map usability experiments for different tasks,and the efficiency,time,and satisfaction of the evaluation results were used as quantitative indicators for measuring usability.Finally,according to the data obtained from the above evaluation,the conclusions and suggestions on the use of wall maps are given.