On The Automatic Generating Algorithm Of Isobath For Electronic Fairway Chart

The Yangtze River is of great importance in the development of Chinese economy. In order to achieve the great-leap-forward development of Yangtze River shipping, China has set up many objectives as the Eleventh Five-Year planning outline of national economy and social development,which are "Improving the conditions of inland navigation,building the Yangtze golden waterway and high-graded waterway net in the Yangtze River Delta,promoting River-Ocean combined transportation", "Applying information technology to enhance the level of transport management, extend the Intelligent Transportation System".This contents that paper research are the core of the Yangtze River Electronic Channel Chart System in "The Demonstration Project of Digital Waterway and Intelligent Shipping Construction covered route segment from Nanjing to Liuhekou",which is the key demonstration project of Ministry of Communications.The construction of this system will not only provide data for the whole demonstration project,but also offer timely and accurate service of electronic channel chart for ships,pilot stations,VTS,Marine Bureau and establishing enterprise relating with ports and shipping.It will fundamentally change the traditional mode of channel management and improve the level of the information services of Yangtze River.Isobath is the line connecting the points underwater with same depth,namely the isograms of depth.The isobaths play an important role in electronic channel chart to ensure the safety of ship navigation,correctly reflect submarine geomorphology,and improve data timeliness and accuracy.In addition,it is one of the important factors which decide the quality of the Electronic Channel Chart.In order to research the automatic generating algorithm for Electronic Fairway Chart and conform digital channel and intelligent shipping system,this paper mainly research on:(1) Discuss various methods to build up TIN(triangulated irregular network) and interpolate,combining the data characteristics of Yangtze River Basin,then choose the method which is up to the mustard and reflect DEM preferably.It will provide a basis for drawing isobaths.(2) Develop the automatic generating algorithm of Isobath applying visual development environment Visual C++.In particular,make a scrutiony into searching the points in building up TIN,judgments criterion of empty circumcircle and the selection of feature edges.(3) Optimize and improve the generated isobaths,especially in smoothing,which make the generated isobaths more suitable for actual demand.