Abstract

Topographic mapping and ocean charting are the outputs of two main surveying techniques for which data has been collected independently for long time. In recent years there has been a growing awareness of our coastal zones to manage our marine spaces in a more structured and sustainable manner. The requirement of this is seamless spatial data coverage across the land/sea interface. The major impediment to achieve this requirement is the absence of a consistent height datum across the land/sea interface. The main objective of this research project was to develop a vertical separation model to define the relationship between the Land surveying vertical datum (LSVD), i.e., MSL/geoid and hydrographic chart datum (CD), i.e., LAT, around Sri Lanka. The vertical datum models were analysed using IDW spatial interpolation with the assumption of the spatial autocorrelation. Polynomial curve fitting of first and the second order has been implemented and both the fitted functions show that the predictions could be made to a higher degree of certainty. The averaged separation of the CD and LSVD is about 0.3 m. The overall chart datum variation analysis suggested that the linear fit seems better with the prediction of the distribution of chart datum variation.

摘要

地形制图和海洋制图是两种主要的测量技术的输出，长期以来一直针对这些技术独立收集数据。近年来，人们越来越认识到我们的沿海地区以更加结构化和可持续的方式来管理我们的海洋空间。对此的要求是跨陆/海界面的无缝空间数据覆盖。达到此要求的主要障碍是在陆地/海洋界面上缺乏一致的高度基准。该研究项目的主要目的是建立一个垂直分离模型，以定义斯里兰卡周围土地测量的垂直基准（LSVD）（即MSL /大地）与水文统计基准（CD）（即LAT）之间的关系。在假定空间自相关的情况下，使用IDW空间插值法对垂直基准模型进行了分析。一阶和二阶多项式曲线拟合已经实现，并且两个拟合函数都表明可以较高的确定性进行预测。CD和LSVD的平均间隔约为0.3 m。总体图表基准变化分析表明，线性预测在预测图表基准变化分布方面似乎更好。