Research On POI Loading Model Of Mobile Map Based On Constraint Hierarchical Road Network Structure

POI(Points of Interest)is one of the most important contents of mobile map expression,it is reasonable and clear presentation which directly affect the expression effect of map.In the map,the measure of geographic elements can be an important standard of clearly displaying is the map loading.At present,although many scholars have done some researches about the map loading,few pay attention to a particular geographical elements,with considering the factors associated with other elements of the basis of its impact on calculation of the elements loading.This has led to the existing set of map loading calculation.Although it can make the whole map sheet loading meet the demand,it can't guarantee that features of each area in the map all meet the requirements.This paper will establish the constraint relationship between the road network and the POI,and calculate the POI loading with consideration of the constraints.It need to establish a calculation model about the loading of POI to deal with vastly different expression map road network.To achieve this objective,you need to consider many issues,including the impact factors of the loading(such as map vector,hierarchical road network,the road segments and mesh,etc.)contained an effect on the POI loading,and how to control the processes of loading calculation.This paper conducted a more detailed study,the main research contents and innovations are as follows,(1)Summarized the expression characteristics of the road network map and POI data,as well as the various constraint relationship between multi-scale map of the road network and the POI.By analyzing the spatial constraints between the road network and the POI,showed a clear constraint relationship between the length of road segments as well as mesh size and amounts of POI.(2)By analyzing the each impact factor of POI loading based on mobile map,summarized the screen resolution,hierarchy of road network,meshes as well as the road segment impact on the loading and their mathematical expressions.Proposed the concept about calculating basis of POI loading and its principles are described in details.(3)Analyzed loading calculation based on the illustration under the limiting conditions,and described the goals of POI loading's calculation model.And on this basis,proposed a calculation model of POI loading in mobile map that is based on the constraints of hierarchical structure of road network.Analyzed the parameter list needed during the process of model constructed and the control mechanism of the model in calculation process.(4)Achieved a prototype with POI expression based on the mobile environment,and the quantity constraints of POI on the map that was based on the calculation model as above.