港口工程水深测量中的不规则区域、任意方向、不等尺度网格法追踪等深线研究

A Study on Drawing Depth Contours Using Grids Based on Irregular Area, Arbitrary Direction and Different Scale in Bathymetric Survey for Port Engineering

规则网格法是计算机绘制等值线的常用方法之一。在港口工程水深测量中,由于水深处理的特殊要求,可能会遇到常规的绘制等值线方法难以解决的问题,如等深线向浅水方向拓展、制图区域的不规则性、水深网格方向的任意性以及网格的不等尺度性。文章提出了浅点相近算法,从而解决了网格法追踪等深线的多义性及向浅水区拓展等问题;为了解决制图区域的不规则性,采用了虚节点标识、双向追踪等措施;为了解决水深网格的任意方向与不等尺度性,提出了采用基于旋转变换和比例变换的方法。理论分析和实际应用证明,文章所提方法在解决等深线的多义性、不规则边界、任意方向、不等尺度等问题上是有效的,能满足港口工程水深测量中等深线绘制的需要。

Grid contouring is one of methods often used for drawing depth contours by computers. Due to special demands of processing soundings, there might appear some problems, which are difficult to deal with by conventional methods, such as depth contour′s extending towards shallow side, irregular plotting area, arbitrary direction of depth grids, and different scale between horizontal and vertical grids. In this paper, a method that the following node should thread the side having a shallower depth is put forward to eliminate the ambiguity in tracing depth contours and avoid extension towards the shallow side; To counter the irregularity of plotting area, measures such as false node noting and double direction tracing are suggested;In consideration of arbitrary direction of depth grid and different scale, the corresponding methods based on rotary transformation and translation transformation are proposed. Theoretical analysis results and practical applications prove that the methods and measures provided in this paper are effective for solving the above-mentioned problems and can be used for drawing depth contours in bathymetric survey for harbor engineering.