Multi-level Visualization Of POI Feature In Indoor Mapping

With the acceleration of urbanization and the rapid development of commercial economy,location services in urban life are no longer satisfied with map services such as positioning and navigation in outdoor large-scale space.Indoor space services characterized by refined services,three-dimensional visualization,and real-time interaction become the new map service direction.The modeling and expression of indoor maps faces a series of technical problems.The complex structure of buildings make it difficult to construct a standardized indoor expression model.The diversified and personalized needs of users in indoor activities increase the difficulty.Taking into account the multi-level user needs of indoor maps is a key issue that needs to be solved.This study focuses on the multi-level visual representation of indoor map,and takes the expression of POI feature as an example to construct the multi-scale expression strategy of indoor map POI to provide technical method support for personalized and intelligent services of indoor map.This paper takes adaptive theory as the research foundation,while the multi-scale expression of electronic map and map symbol expression theory are technical support.The aim is to provide personalized,intelligent and diversified map services.The multi-level visualization strategy of indoor map POI is studied from the aspects of map content and form.In terms of the content expression of indoor map,this paper starts from spatial cognition and summarizes the characteristics and methods of indoor map visualization.Then,according to the characteristics of indoor map and taking shopping center as an example,indoor map elements are divided into four categories: indoor frame elements,user interest elements,public service elements and indoor traffic elements,among which indoor frame elements and user interest elements are the focus of this paper.Indoor map frame element is the background of the map expression.To achieve the refinement of the indoor map expression,this paper uses the LOD technology to build the multi-scale three-dimensional expression model,which can realize the hierarchical expression of “building-floor-room-point”.The effect and provide three application modes: indoor and outdoor integration,multi-floor and single floor expression.In the aspect of indoor map form expression,map visual variables are used to design indoor map symbols.Map symbols can adaptively adjust their symbol schemes according to user operations and display scales to adapt to the current expression environment.POI is the element that users are interested in in indoor map.Based on the above research,the multi-level visualization strategy of indoor POI elements is studied.In terms of map content expression of POI,the concept and content of POI are first introduced,and the expression characteristics of indoor map POI are summarized according to the characteristics of indoor space.Then,based on the semantic information,the indoor POI elements are classified as the basis of the hierarchical expression.For POI content hierarchical expression,this paper proposes two strategies: the first is POI multi-scale expression strategy,Considering the semantic and spatial features of POI,the importance model is constructed.Then,based on the square root model,the qualification scale of each POI point is set.Finally,the conflict of symbol display is processed through conflict detection,so as to realize the multi-scale expression of POI.The second is the different visualization methods of multi-scale POI.The distribution characteristics of POI in different scales are analyzed,and a POI visualization strategy based on distribution characteristics is proposed,which reflects the scale adaptation of the visualization method.In terms of the formal expression of POI,the symbolic expression of POI semantic information is mainly considered,and the LOD model of POI semantic level is constructed by combining the design principle of map symbols and the principle of visual variables to study the symbolic expression of POI point symbols in different semantic scales and its adaptive rules.Finally,based on the results of this paper,wanda plaza is taken as an example.Based on WebGL,a multi-level expression system for indoor maps with good interactive functions and visual experience is developed in Mapbox.The system can achieve outdoor two-dimensional map and indoor three-dimensional map of seamless switching and single floor and floor model of switching operation.Each floor can take out like a drawer,in which POI is clearly visible.At the same time,POI can express detailed service information through different symbolic styles,and users can obtain information of interest through interactive operation.This study provides a new idea for the multi-level expression of three-dimensional indoor map of large buildings,which can be applied to a variety of indoor scenes,such as shopping malls,hospitals and airports.