After data is collected, it has to undergo post-processing. A massive amount of data is collected during the typical hydrographic survey, often several soundings per square foot. Depending on the final use intended for the data (for example, navigation charts, Digital Terrain Model, volume calculation for dredging, topography, or bathymetry) this data must be thinned out. It must also be corrected for errors (i.e., bad soundings,) and for the effects of tides, heave, water level salinity and thermoclines (water temperature differences) as the velocity of sound varies with temperature and salinity and affects accuracy. Usually the surveyor has additional data collection equipment on site to measure and record the data required for correcting the soundings. The final output of charts can be created with a combination of specialty charting software or a computer-aided design (CAD) package, usually Autocad.
after data is collected it has to undergo post-processing a massive amount of data is collected during the typical hydrographic survey often several soundings per square foot depending on the final use intended for the data (for example navigation charts digital terrain model volume calculation for dredging topography or bathymetry) this data must be thinned out it must also be corrected for errors (ie bad soundings) and for the effects of tides heave water level salinity and thermoclines (water temperature differences) as the velocity of sound varies with temperature and salinity and affects accuracy usually the surveyor has additional data collection equipment on site to measure and record the data required for correcting the soundings the final output of charts can be created with a combination of specialty charting software or a computer-aided design (cad) package usually autocad