Establishment and Transformation of the Vertical Datum in Hydrographic Surveying and Charting

This paper presents some points about vertical datum which catches more and more attention in hydrographic survey and charting,include the present situation of vertical datum,the relationship among the vertical datum planes and so on.In order to realize seamless joining of coastal topographic map and bathymetric chart,the transformation technique between the datum planes of coastal topographic survey and bathymetric survey is also researched.