Quality references in the Abstract and/or Lineage, although the ISO19115 Data quality elements within (MD_DataQuality) can also be used to document precision and accuracy more fully.Data quality allows users and user systems to assess fitness for use of the provided data. Data quality measures and the associated evaluation are reported as metadata of a data product. This metadata improves interoperability with other data products and provides usage by user groups that the data product was not originally intended for. The secondary users can make assessments of the data product usefulness in their application based on the reported data quality measures.
For this <L0 Raw MBES Data Specification> the following Data Quality Elements will be assessed[1]:
Conformance to this Product Specification
Intended purpose of the data product
Completeness of the data product in terms of coverage
Logical Consistency
Positional Uncertainty and Accuracy
Thematic Accuracy
Temporal Quality
Aggregation measures
Validation checks or conformance checks including:
General tests for dataset integrity;
Specific tests for a specific data model.
Using QAX
Quality assurance on raw data using the MATE plugin in QAX is mandatory.
QAX is an open-source project, jointly steered by AusSeabed, the United States of America National Oceanic and Atmospheric Administration’s Office of Coast Survey (NOAA OCS), and the University of New Hampshire’s Center for Coastal and Ocean Mapping (UNH CCOM). QAX version 1.0 is available on the AusSeabed GitHub (https://github.com/ausseabed/qax/releases ).
QAX facilitates quality assurance (QA) of multibeam echo sounder (MBES) data. It provides an efficient workflow for checking MBES data. The tool standardises QA outputs and assists the technician to perform a robust QA of data.
This assessment must be performed within data structure submitted to AusSeabed. This includes MBES, SVP, Navigation & Attitude or Trueheave data. The qajson file and screen capture of the summary from QAX (Figure 1) are required along with raw data on submission to AusSeabed.
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Figure 1. An example of screen capture of the result summary from QAX.
At minimum, the Bathymetry Available and Backscatter Available checks need to pass even if any other checks fail or have warnings. We also expect to see the presence of other ancillary data in qajson file that QAX is able to detect such as true heave/navigation and svp files in the data level which is ready and readable for bathymetry processing.
For full details on Quality Assurance see the AusSeabed Quality Assurance Framework
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[1] As deemed necessary by the IHO –Hydrographic Standards and Services Committee