| Any special action such as emergency security, safeguard stability etc. happens in a certain geographic space. The geospatial awareness for these situations is an important guarantee to grasp the initiative and win the victory. GIS is the primary means of geospatial cognitive in digital conditions. GIS has played a huge role in military field. For general navigation system, map navigation system will be more complex to these special applications. Currently, GIS theory and technology based on the desktop is relatively mature. But the application research of geographic information under maneuvering conditions still lags behind. The map navigation based on embedded-GIS can provide effective means for complicated geographical environment awareness under maneuvering conditions, which becomes an important research direction for future mobile geographical information application and service.Map navigation system using in complicated geographic situation is restricted by the limitation of embedded environment resources and the diversity of embedded platforms. It also needs to consider the limited factors such as the complicated situation and application subjects. The current research on embedded-GIS mainly aims at specific embedded platforms, which is unable to meet the requirements of platform diversity. Static information supports the information application. Key algorithms need further study in order to solve the above problems. This dissertation use the military applications of map navigation system as the research object, put the dynamic information into a navigation application, study and solve the key technologies about cross-platform mechanism, data organization and retrieval, visualization and path planning issues that is based on embedded platforms with limited resources and complicated situational applications. The detailed descriptions are as follows.Firstly, the background and significance of the research oriented the map navigation based on complicated situation are described. The research status at home and abroad about embedded-GIS and map navigation related fields are introduced. Then this dissertation analyzes the GIS composition, application areas and relevant technical standards, summarizes the development trend of embedded-GIS and navigation systems, and analyzes map navigation system problems facing complicated applications.Secondly, concepts and elements of complicated geographical environment are introduced. Starting from the theory of spatial cognition, based on the advantageous, accessibility and mobility features of the complicated geographical environment, the dissertation analyzes geographical cognitive subject, cognitive object and cognitive purpose of the complicated geographical environment. This dissertation proposes a spatial cognition model oriented map navigation system in mobile environment, and two key technical problems on visualization and path planning that affects navigation cognitive. Embedded software developing technics are discoursed based on the analysis of embedded systems hardware and software environment's differences and the characteristics of embedded systems. Dynamic information is introduced into map navigation. Concept and classification dynamic information are described. This dissertation analyzes the relationship among dynamic information of the complicated geographical environment, situational awareness and information visualization, defines the dynamic information model including related elements of the roads and targets. Dynamic information supported mechanisms and navigation system's architecture based on Beidou short messages are designed, which provides an effective way for information acquisition, transmission and application.Thirdly, to solve the adaptability for a variety of embedded platforms, this dissertation analyzes dependence between the map navigation system and embedded hardware and operating system environment, designed a cross-platform mechanism based on abstract layer, shielding the differences between different embedded operating system. This dissertation designs and develops a lightweight graphic middleware suitable for embedded environments that is named LEMD_MW, which uses hierarchical design. The specific functions are encapsulated through the graphics application development interface, control layer, core layer, public layer and adapter layer. Each layer of LEMD_MW's design and function are discussed in detail. Using abstract class in object-oriented methods, this dissertation implements LEMD_MW's operating system adaptation layer and application framework.Fourthly, in order to solve contradiction between the embedded environment resource limitation and the navigation system real-time requirements, this dissertation analyses data types that are included in the map navigation for the complicated application environment. Based on the relationship between the embedded environment resource constraints and navigation requirements, the embedded environment resource constraints model is defined. Multistage tiles data organization model (vector grid integration) and multilevel hybrid indexing mechanism are designed. Organization model bases on the grid tiles and vector tiles, adopting a classification, hierarchical, block strategy to organize and manage the navigation map, topographic maps and image maps and other types of display data. And in accordance with the scale linearly graded index, the data block grid index, the elements in the data block R-tree index rules, this dissertation builds an indexing mechanism. The organization of path analysis data is based on logic block. The same organizational model and indexing mechanism support the unified management and retrieval. Experimental and applied practice show the organization model and the indexing mechanism is highly efficient, which meets the requirements of practical applications.Then, this dissertation designs a cross-platform map visualization mechanism based on LEMD_MW and describes the cross-platform map display framework based on middleware. Cross-platform map symbol library architecture and map display mechanism are designed and implemented which is suitable for resource-constrained embedded environments. The embedded-map visualization algorithm is analyzed. The Multi-Cache block Parallel Display algorithms (MCPD) is designed to achieve a more rapid map visualization requirement, based on multi-cache and parallel computing strategy. The algorithm is verified by experiments, which shows that meets the embedded environment maps rapid visualization requirement.Lastly, Aiming at the path planning problems in the complicated application environment, the dissertation analyzes the impact factors affecting the navigation path analysis, defines the path planning model based on attributes of roads influencing factors and decisive factors, put the dynamic information into path planning model, and designs a weight normalization method as a reference to the limiting factors using the distance as the base unit. Comprehensive weight calculation methods of the affecting factors are defined. On the basis of the definition, this dissertation presents the dynamic path planning method. Aiming at navigation map data and embedded environments' requirements for optimal path algorithm, this dissertation designs and implements hierarchical secondary search A* algorithm, which is based on converted road network. The algorithm reflects more obvious advantages than the conventional Dijkstra at computing speed and resource consumption rate. |
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