Completeness and Data Gaps

Definition

Completeness is also a first-order measure of data integrity in the quality measures check step.

In this step we use the bathymetry processing software to run several checks to evaluate the completeness of the data according to the level of the data (L0, L2 and L3) products should be consistent with Multibeam Guidelines (section 2.3.1.2 Table 5).

Holidays are defined as data gaps in data or areas where accuracy requirements have not been met. In QAX QA/QC data gaps will be flagged and will require a closer inspection of the operator

Data gap can be caused by:

1. Vessel manoeuvring

2. Survey equipment problems

3. Unexpected shoals

4. Rejection of poor-quality data during post-processing. NOAA Field Procedures Manual

Wherever possible, nearing the conclusion of data acquisition, a review of data coverage is highly recommended and infill lines conducted to ensure there are no gaps in the bathymetry, as this impacts the suitability of the data for end use. Additional lines over significant shoal features are also recommended to ensure good density of soundings and determination of least depth. Australian multibeam guidelines 4.1 survey Plan

Completeness Checks

1. Check the completeness of the input data (L0) (If the transit lines to and from the AOI are loaded/ first and last files is included) 

2. Check the processed (L2) cleaned data is complete and match the entire dataset. (data missing due to severe filter) 

3. Check the output (L3) 32 Geotiff grid is complete and match the entire dataset. 

4. Use QAX QA/QC tool to scan for data gaps 

Pass Requirements

1. Completeness: Depending on level of data received; is the L3 grid complete. 

2. Data gap: Run the 3-band 32-bit Geotiff grid through QAX QA/QC and ensure that the data passes. 

Please note that in some cases the survey will appear not to pass the data gaps check, however if this is only on the boundary of the survey this will be considered a pass.

Example 1

Description

20180011S Beagle Marine Park (GA-0364)

Test results

Open

Figure 1: Data gaps: Failed.

Open

Figure 2: Data gaps check shows the location where it failed, on the boundary of the survey

Pass

Yes

Explanation

This dataset pass checks 1 and 2 as listed above.

While the data gaps check failed, it was only on the boundary of the survey, hence we determined that it passed.