A New Synchronous Visualization System for Time-sequential 3D Geographical Scene Display on a Computer with Multiple Screens

Abstract

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 interpolation 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 vegetation 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 viewports,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 also features dynamic change,enormous information,and strong expression.It has unique application capability for visualizing dynamic geographical scene.Last,these function modules are integrated in the 3D information system for synthetizing and management of virtual forest landscape(VisForest) which was designed and developed by research group coming from Spatial Information Research Centre of Fujian.