hydrographic surveying

Hydrographic surveying has evolved in the last 20 years. Different revolutions in ocean mapping technologies have made new ocean mapping applications possible. Positioning Most positioning at the sea is done using GPS. This routinely supplies cheap, consistent, accurate positions, globally referenced, easily accessible and accurate positions to the largest tanker and smallest pleasure boat. In most cases, GPS positional uncertainty is smaller than the uncertainties in the existing nautical charts and ocean maps. When nautical charts are replaced with ones that are compatible with GPS uncertainties, having smaller uncertainties, it becomes a big challenge that some electronic charts advocates argue is not worth undertaking. Promote sensing information Airborne images and satellite technologies have revolutionized ocean mapping in different ways. Features of the ocean surface as small as few centimetres in height and altimetry from satellites maps changes in. such …