一种改进的海图等深线更新方法

An Improved Method for Updating Depth-contour in Nautical Chart

针对当前等深线更新方法在等深点生成环节未能充分顾及航行安全的问题,结合可能最浅水深概念和抛物线插值法,提出一种顾及航行安全“扩浅缩深”原则的等深点生成算法,并据此算法实现等深线更新。首先根据海图水深点构建并优化Delaunay三角网;其次采用一种顾及“扩浅”原则的等深点插值算法确定等深点的位置;最后在等深线追踪完成后,采用顾及航行安全的光滑算法绘制出形状平滑的等深线,实现等深线自动更新。实验结果表明,该方法更新的等深线能够正确表达海底地形,符合海图等深线绘制的航行安全原则,满足海图等深线要素的更新要求。

To address the problem that the current depth-contour updating methods cannot fully consider navigation safety in the depth-contour point generation process,an improved depth-contour points generation algorithm considering safety constraint based on possible shallowest sounding and parabolic interpolation is proposed in this paper.According to the presented depth-contour points generation algorithm,the updating of depth-contours in nautical chart is realized.Firstly,the Delaunay Triangulated Irregular Network(TIN)of chart soundings is constructed and optimized.Secondly,positions of the depth-contour points are determined using the interpolation algorithm proposed in this paper which takes navigation safety into account.Finally,contour points are tracked and depth contours are smoothed to realize the update process.The experimental results show that the updated depth-contours can express the submarine relief correctly and satisfy the safety constraint.The presented method meets the requirement of updating depth-contours in nautical chart.