Sea Technology

SEP 2017

The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community

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Page 24 of 68

24 st / September 2017 require human input to ensure quality. Unlike systematic TPU, which can be es- timated, human TPU is unpredictable and cannot be measured. Typical areas for hu- man TPU are: transcription—at least three coordinate frame conventions exist within a single installation distributed across a minimum of eight software interfaces, and humans are prone to error when convert- ing from one frame to another; process- ing—failing to apply imported ancillary data; and reprocessing—changing config- urations and then not triggering the appro- priate reprocessing, and/or not triggering the appropriate reprocessing for the files that need it. Minimizing TPU, both systematic and human, represents a logical evolution in the hydrographic workflow. Guided Workflows, Real-Time Processing In 2000, QPS introduced the QINSy guided workflow (to assist users during the acquisition setup process) and real- time processing. The guided "Wizard Based Setup" provides guidance for project preparation including: template data- base creation (guided geodesy, vessel setup, hardware inter- facing) and online preparation (data-recording setup, pre- data filtering, calibrations and field checks). The real-time processing allows for all computations to be done in real time such that post-processing has zero computation time and reduces the effort to simple data cleaning. Following in suite with the QINSy model, QPS has evolved the guided workflow to data processing. The solu- tion is known as Qimera and represents a paradigm shift in hydrography. Qimera incorporates the QINSy hydrographic engine with the Fledermaus 4D visualization and multi- core processing engines to provide users with a seamless, Uncertainty Within the vessel installation of a multibeam hydrograph- ic survey system, uncertainty accumulates that is known as Total Propagated Uncertainty (TPU). The TPU of a point is a measure for the accuracy to be expected for such a point, when all uncertainty sources are considered. The TPU can be computed statistically using the well-known Law of Un- certainty Propagation, hence the indication "Propagated." The TPU value thus results from the combination of all con- tributing uncertainties, hence the indication "Uncertainty." What is not considered is the "human uncertainty" in any given workflow. Quality controls are imposed that mini- mize error, however, mistakes happen and their cumulative totals result in what has been referred to as "human TPU." During acquisition, survey logs note line names, positions, start/stop times, features (shoals, wrecks) and unique obser- vations. During data processing, checklists provide guides to ensure proper application of ancillary information (e.g., tides, sound velocity, post-processed heave). The common denominator with survey logs and checklists is that they (Top) Sample of the variation in coordinate frames found within any given hydrographic workflow. (Bottom) Typical Qimera data- processing environment featuring a dynamic surface recently updated to show an inadvertent data edit completed within the Slice Editor.

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