The evaluation of current chart adequacy (as well as the rectification of possible deficiencies and shortcomings) represents a world-wide pressing need that poses a challenge to many national hydrographic offices. Those offices must balance such a pressing need with the limited available resources and survey priorities that translate to the fact that decades may past until a new hydrographic survey can be conducted in a given area. Bathymetric-sonar surveys – despite their high cost and logistic challenges – not only provide both highly accurate and dense measurements of the seafloor morphology, but also represent the only practical source of hydrographic information for large parts of the ocean.
The identification of nautical chart discrepancies in comparison to newly collected hydrographic survey datasets has received only limited attention in the scientific literature despite its importance for the safety of navigation and relevance in the evaluation of the adequacy of the current charts, as well as for coastal change analysis and coastal zone management. In addition, many of the techniques developed for geospatial data analysis on land cannot be straightly applied to the nautical cartography realm, mainly because of the peculiar safety of navigation requirement.
Currently, the task to identify chart discrepancies against new data sets is usually performed by the various cartographic agencies through manual or semi-automated processes, based on best practices developed over the years. However, these processes require a substantial level of human commitment that includes the visual comparison of the chart against the new data, the analysis of intermediate support products or, more commonly, a combination of the two. Thus there is a need of algorithms that automate a large extent of the change detection process and to reduce its subjective human component.