大规模3DGIS场景的多通道渲染算法研究

A multi-channel rendering algorithm for large scale 3DGIS scenes

为了由多个计算机节点协同完成大规模三维地理信息系统(3DGIS)场景的渲染和显示,提出了一种基于分布式计算机体系结构的多通道渲染算法(3DGIS multi-channelrendering algorithm,GMCR)。三维地理信息系统同其他类似算法相比,该算法作了两项改进:(1)采用视锥组合计算方法将大规模三维场景分割为若干子场景并分配给不同计算机节点处理,可以保证场景拼接处的空间连续性和不变形性;(2)采用消息机制协调计算机节点的渲染处理与显示步调,以控制子场景的状态同步和显示同步。该算法简单易行、效果突出,利用多台低端设备实现了大规模3D场景渲染与显示,可以完成高端设备不能够实现的超大规模3D场景。以3DGIS城市交通系统演示环境实验为例,验证了该算法的可行性,结果表明GMCR方法可以支持多达185个计算机节点进行超大规模的3DGIS场景渲染。

In order to implement large-scale 3DGIS scene rendering through utilizing numerous display terminals, this paper presents a new multi-charmel rendering algorithm, the GMCR （3DGIS multi-channel rendering algorithm）, based on a distributed computation architecture. Compared with other multi-channel rendering algorithms, the GMCR has two important improvements as below. Firstly, it uses the perspective cone composition method to decompose a large scene into a few sub-scenes and allocate them to different computer nodes for processing, but keeping graphic congruity and shape un- deformation. Secondly, it adopts the message-based communication method among distributed computer nodes to syn- chronously coordinate the rendering and displaying of sub-scenes. The GMCR is simple but quite effective. It drives mul- tiple low-cost equipments and performs high-quality large-scale 3D scene rendering, a goal that even a high-end graphic device may not reach. The demonstration of a 3D urban transportation system proves the feasibility of this algorithm, and the result shows that, the GMCR can support computer rendering nodes up to 185, which enables a super-scale 3D scene rendering enough in a 3DGIS.