三维地理场景的可视化是虚拟地理环境研究中展示各类复杂地学过程与现象的重要技术。目前,现实中地理场景大多具有复杂度高、规模大、交互性强等特点,故采用传统的单个计算机单屏显示方式,已无法满足用户对沉浸感、大视野、高分辨率的可视化应用需求,而多屏显示技术是一个解决该问题的有效途径。本文以福建长汀县水土流失治理过程中植被覆盖变化为例,开展了时序三维地理场景的单机多屏同步可视化技术和漫游系统研究。提出了系统的软件架构和开发流程,并引入多线程同步机制,实现了三视图场景的构建、三屏同步显示、三屏同步路径漫游、矢量图的差异符号化和三维场景实景图片嵌入播放等技术,设计并实现了一个以单个计算机控制三个显示屏幕的时序同步可视化漫游系统。采用3个时相的彩色遥感卫星影像,叠加数字高程模型形成反映不同时期水土流失程度变化的三维地理场景,在水土流失治理过程成果展示中得到了应用。系统除了三维场景沉浸感强、震撼力大之外,还具有动态变化、信息量大、表现力强等特点,在地理场景动态可视化方面有独特的应用前景。
Three-dimensional (3D) visualization of geographical scene is an important technique in Virtual Geographical Environment (VGE) research for a broad variety of complex natural phenomena and geographical processes. Because geographical scenes are in general highly complex, large scale and with strong interactivity features, traditional single computer single-screen display method usually fails to meet the application requirements of user immersion, large field of view, and high-resolution visualization. Multi-screen display technique is an effective way to solve this problem. In the human-computer interaction of 3D geographical scenes visualization, in addition to supporting to control by hand through the input of keyboard, the system also supports automatically roaming along the path designed in advance. The path for automatically roaming is generated by Cardinal inter- polation method which have some advantages: setting simply, good shape retention, and roaming smoothly. In this paper, a new synchronous visualization technique and system for time-sequential 3D geographical scenes displaying and roaming is introduced. The system is based on a stand-alone computer with multi-screens, using veg- etation cover changes prior to, during and after the soil erosion control in Changting County, Fujian Province as an example. The software architecture, implementation techniques such as scene construction with three view- ports, synchronous display and synchronous route roaming with three screens, vector layer symbolization, embedded broadcasting real-world scene pictures of 3D scene are discussed; thread synchronization mechanism is introduced; a 3D geographical scene was constructed to reflect the changes of soil erosion extent at three different time periods by overlaying true color remote sensing satellite images and DEM. This system has been used for showing the achievement of soil erosion control, and the effect sounds good. In addition to providing a strong immersion and big impact environment, the system a