Hydrographic surveying analyzes the sea and ocean to see what the floor looks like. It describes and measures the physical features of the navigable portion of the surface and coastal areas, in relation to the use for the purpose of navigation.
During the survey, speal attention is paid to locate the least (shoalest) depths, to warn mariners of dangers to navigation. Tides and water level measurements are recorded to provide a vertical reference for water depths.
During the survey, floor materials - like sand, mud and rock - are recorded. This can be important for dredging, anchoring, dredging, pipeline routing, cable routing and more.
Hydrographic Surveying is usually done using an Echosounder,
a GPS receiver, a tide receiver and a software package like ActiveXperts Hydromatic for Windows>.
The software collects all position- and depth data, stores it in a database and creates nautical charts based on the information gathered. The charts usually have backgrounds imported from a known grpahical file format (including AutoCAD DXF, Microstation DGN and GeoTIFF).