Quality assurance

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 <L2 Processed 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

• Resolution

• Data Fliers

• Data (Sounding) Density

• Data Gaps (Holidays)

• Aggregation measures

• Validation checks or conformance checks including:

  • General tests for dataset integrity;

  • Specific tests for a specific data model.

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.

Using QAX

Quality assurance on L2 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 Centre 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 processed multibeam echo sounder (MBES) L2 data (in gsf format). 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 processed L2 MBES and optional ancillary data such SVP, Navigation or Trueheave data that used to produce L2 data. The qajson file and screen capture of the summary from QAX (Fig. 1) are required along with L2 data on submission to AusSeabed.

Open

Figure 1. An example of screen capture of the result summary from QAX.

At a minimum, the Bathymetry Available and Backscatter Available checks need to score a pass even if other checks result in fail or have warnings. The inclusion of ancillary data is optional because we expect that all required ancillary data have been already applied to the L2 MBES data supplied.

For full details on Quality Assurance see the AusSeabed Quality Assurance Framework