Virtual Representation Study On Dynamic Changes Of Coastal Zone Terrain

Virtual representation study on dynamic changes of coastal zone terrain is the keystone for the combination of Geographical Information System (GIS) and Virtual Reality (VR) technology, and it is also the main content of Digital Estuarine and Coastal Zone. VR technology based on Geo-VRML (Geography Virtual Reality Modeling Language) can achieve Real-time rending and interacting of established terrain model and virtual scene, so it constructs rich and colorful model and scene. With the development of marine science and computer science including software and hardware, more and more VR technologies are using in the hydraulic engineering researches. Virtual representation study technology on dynamic changes of coastal zone terrain has gradually become the main considering means for coastal zone, sea-route and port engineering to research and devise silt sediment or eroding and riverbed evolvement, and engineering to maintain and design too. Real terrain information recurred effectively, vividly and dynamically by using VR technology. It also provides technology supporting for scientists to research deeply and analyze synthetically.The research is supported by the task of information server platform of tidal flat resources environments. This task is part of Shanghai Science and Technology Committee's project, which is Study on Sustainable Development of Tidal Flat of Shanghai. The purpose of the task is to achieve virtual representation dynamically of tidal flat, and to provide resource data exchanging, environment sharing and heighten resource data utilization efficiency eventually.Taking the north passage of the Yangtze estuary as a study area, a 3D terrain model of the area is established with data, digitized from 12 sea charts from 1965 to 2003 and aided by Multigen Creator, a professional tool for terrain modeling. Furthermore, the texture and feature data is also projected, so the terrain model is more vivid, and a virtual representation of the 3D terrain model is achieved with Geo-VRML and browser package Cortona. Based on the modeling, spatial variations of the north passage thalweg from 1965 to 2003 are analyzed, and the evolving process of islands in both sides of the passage is discussed thoroughly. On the base of modeling, we design and develop the virtual explore system of the Yangtze Estuary.