The Optimal Selection Research Of Multiple Scales In Electronic Map Based On Concept Lattice

With the development and continuous application of computer technology,the map’s expression medium has transferred from paper to computer.The entire landscape of the city,the country,and even the earth can be observed between inches in the computer.The display range is also very broad.Compared with traditional maps,electronic maps display geospatial information as an expression of map visualization,which avoids the limitations of scales and maps and achieves scaling between multiple scales at random.The expression of the map has also changed in the background of the digital environment.In order to meet the human visual experience and the cognitive process of geography,the content of the display screen is dynamically adjusted with the transformation of the scale by combining map visual perception theory with information transmission theory.Electronic maps have greatly improved on interactivity and legibility compared with paper maps,which makes it easy to read and manipulate maps.However,the display effect of scale selected from multiple scales in the current electronic map is often unsatisfactory.It is difficult for users to capture the specific location information of the target feature when users search and observe the specific location information of the target feature in electronic map.The information displayed on the map is easily rough when the scale of the electronic map is smaller.The display information is excessively detailed when the scale becomes larger.Therefore accessing to the overall message from a certain generally height is hard for users.At this time,the detail information cannot be provided,thus the users have to perform a large number of scaling operations,which reduces the reading efficiency and the experience effect of users.Aiming at the question of how to select the appropriate scale for observing the target features for users,this dissertation develops the following study.(1)Concept lattice is a powerful tool for data analysis,which describes the relationship between objects and attributes,reflects the generalization and specialization between concepts,and the corresponding Hasse diagram to achieve visualization of the data.Introducing a quantized number of extension in the concept is to record the index position of objects of extension.The quantization number represents the maximum index of objects in the extension.The first index starts from one.The index position is incremented by one.Different scale zoom levels lead to different levels of detail about display information in the electronic map.The idea of the concept lattice is introduced into the electronic map,and the relationship between multiple scales and their landfeatures is described by the objects and attributes of the concept lattice.So a concept lattice for multiple scales and land features is proposed.(2)Optimal selection of multiple map scales in electronic map based on concept lattices.The concept lattice is constructed by descending multiple scales mark scales as the objects of the concept lattice,and land features of multiple scales be as attributes.The multiple scales and their corresponding features can be clearly viewed in the Hasse of concept lattice.Then the first concept node is found from top to bottom according to users’ target land features.The scale,the maximum index position of extension of above-mentioned node corresponds,is the appropriate scale.This optimal selection algorithm can select the appropriate scale to observe the target features for users.And on the premise of not losing the target position information,the user only needs to switch multiple map scales included in the concept extension to avoid excessive scaling.(3)Optimal selection prototype system of multiple map scales.The system uses Baidu maps as a data source,mainly consisting of data preprocessing,concept lattice generation and multiple scales optimization.The electronic map takes the user’s input interest object as the input of the system.After processing and analysis of the three functional modules,the optimal scale and the alternative scales are taken as the result set and returned.Construct concept lattice for multiple scales and land features by using the six scales corresponding to grades 2 to 7 of Baidu maps and the roads and POI features near Shanghai Dishui Lake as system application data.Taking the vegetable market in guzong road as target object of user interest.The optional selection scale is compared with other scales to show the effectiveness of the multiple scales optimization algorithm and the feasibility of the prototype system.