Research Of Task Scheduling For Rendering Terrain By Block Computing In Grid Environment

Real-time rendering terrain is an important component of virtual reality technology, it have a wider range of applications in the military simulation, geographic information systems, and other fields. However, real-time rendering technology mainly face the single computer, as the hardware conditions restrictions of individual machines, it may appear that the terrain server or workstation users can not satisfy real-time rendering while multi-user visit at the same time.Based on the study of single computer rendering technology and grid computing, this paper proposes a terrain rendering technology based on the grid. Using grid task scheduling to solve the inefficiency of terrain rendering caused by hardware reason in multi-user visit at the same time. This paper mainly did the following work to achieve terrain rendering in the use of grid task scheduling:1. This paper porposed a T-MIN-MIN scheduling algorithm with the terrain characteristics, and designed a terrain block scheduling model. According to the terrain characteristics, T-MIN-MIN algorithm scheduled some certain proportion terrain blocks, and scheduled other blocks by MIN-MIN algorithm, this method can maintain load balancing. The test proved T-MIN-MIN scheduling algorithm had better effect.2. As the task scheduling allocated by assignments of tasks, so this paper proposed terrain block LOD time estimation method. This method found to meet the conditions of the node by judging the distance between the midpoint and midpoint of triangle hypotenuse whether landed the error criterion ball, and fast calculated the overall number of triangular formation by the formula. The terrain block allocated by estimation, which can avoid the scheduling of tasks allocated blindly, ensure the load balance between the resources.3. Against terrain rendering problems after viewpoint changed, this paper proposed a task dynamic change method after viewpoint changed base on the exiting algorithm of grid tasks'load balance. And against the changing of level detail after viewpoint changed this method dynamically adjust the mandate to reduce terrain block adjustment time and the consumption of resources. Finally, this paper compared the multi-user real-time rendering of the terrain in the server with grid environment by tests. The results show that the grid can better achieve real-time rendering of the terrain while multi-user visit at the same time.