Study On Key Technologies For Visualization Of Space Environment

With the extension of humanity's scope of activities, outer space has become an important area for space activity and scientific exploration. And space environment plays an increasingly critical role in humanity's living and working activities, especially in the field of military operation. However, rules of space environment elements have not been mastered completely due to its complexity and peculiarity. Visualization Technology, as a tool for understanding and discovering knowledge, offers a method for seeing the unseen, has a function of cognitive analysis and communication, can speed up the process of data management, and is an effective tool for understanding and discovering scientific disciplines. Centered on visualization for space environment, its key technologies have been discussed from aspects of space environment elements'analysis, setting up a uniform framework for visualization, data organization and management, mapping and rendering of data and the user interactive control.From the perspective of setting up a visualization system for space environment, models of main space environment elements in existence were investigated widely. And their input and output parameters, reference objects for describing parameters in time and space domain were categoried and summarized in table and graphic mode.The definition, expression mode of spatial position of all involved coordinates in the solar system, and their interrelationships were investigated deeply. Using the idea of scene graph in game engine for reference, a visualization framework was constructed hierarchally, which can satisfy all kinds of requirements of visualization for space environment or space mission.Reasonable and effective data management techniques play a significant role in improving the efficiency of program, especially for those which process large data volume. Using the data of absolute density of solar wind, factors which influence the rendering efficiency were analyzed, and further improvements were pointed out. Vivid graphic representations can assist understanding and discovering data in largely. Based on the stage of data mapping and rendering in the course of visualization, general visualization methods were summarized. Visualization methods for space environment were explored from the aspect of vector datafield, scalar datafield and physical objects. A case study of visualization for data of geomagnetic field and absolute density of solar wind was illustrated by points, lines, planes and volume method. And their traits and application scopes were concluded and summarized in later. Also, model and rendering methods for earth, atmosphere and sun were introduced.A good viewpoint control method can improve visual effect largely. Difficulties in the process of viewpoint control were discussed, especially in the situation of visualization for space environment were analyzed in detail. A constrained navigation mode, plus path-based mode was implemented in virtual space environment. The constrained mode can orientate user desired position conveniently and quickly, and precisely positioning the observer in large scale scene. The path-based mode woks well in in the situation of finely time granular or without requirements of user interactive control. It has been proved that the conjunction of both modes meets user's requirements in interactive control commendably.The studies in this paper provide multiple technical supports for research and application of space environment, provide means of simulation and analysis for space science mission planning, and lay a foundation for the establishment of space science information system.