Research on the determination and algorithm of chart datum

Chart datum is a vertical reference of ocean depth, which can give the ocean vertical spatial information for Marine Geographic Information Systems. Its establishment and maintenance is the fundamental work of hydrography and cartography. Paper introduced the chart datum´s role in ocean vertical datum, analyzed the basic principles to determine the chart datum, and studied the spatial structure of ocean bathymetry based on chart datum. In the end, it summarized the international current algorithm, model and the study progress of chart datum. For the construction of digital hydrographic spatial information, it is necessary to reconstruct the vertical chart datum system for coherence.