A Time/Effort Comparison of Automatic and Manual Bathymetric Processing in Real-Time Mode

In September 2002, the NOAA Ship RAINIER hosted an experiment to examine the benefit in processing time from adopting CUBE [Calder & Mayer, 2002] and the Navigation Surface [Smith et al., 2002], and to determine whether this methodology could be used in real-time. Using normal survey methodology, data were collected from multiple platforms in Valdez Narrows, AK (~10x10km, 0-300m depth, slope 40-60°). Seven boat-days of data were collected, containing 22.3×10 raw soundings. We obtained a copy of the ship’s data after correctors were applied, but before any handedits had been done, and then ran the data through CUBE where multibeam data was available, using a TINing algorithm to junction singlebeam, shoreline and other features. Next, we inspected the data using GeoZui3D for visualization and CARIS HIPS for remediation. A final pass through CUBE resulted in an updated ‘current survey estimate’ to proceed to the next day; after all data were collected, a final sweep through the data completed the editing process. Throughout the process, the ship’s survey team recorded time expended on the project, broken into interactive and non-interactive tasks, with finer sub-divisions such as data manipulation time and line-oriented (swath) editing, etc. Since the CUBE effort concentrates on data processing, we recorded only this category. The experiment showed that the extended algorithm can be used in a real-time mode, and is significantly faster than the traditional processing stream in operator effort to achieve the same result. We found that a tight integration of visualization and remediation tools will be required in order to achieve the most benefit from the method, and that the expected benefit will vary with the quality of the data. The challenging geomorphology precipitated problems that were obviously better solved in line-oriented mode, highlighting the fact that there is no universal solution to the bathymetric modeling problem. Our analysis also shows that, in the traditional processing stream, the most significant time expended during the survey is in swath editing, followed by line planning and quality control. In post-survey, time expenditure is dominated by interactive editing. We note that these results are only a point in a spectrum of survey types, and may not be typical.