Resolution

Definition 

The level of detail discernible in a gridded multibeam bathymetry dataset. Resolution is measured in metres by the length and width of a pixel. Resolution is determined by data density which correlates with equipment specifications and sea bed depth. Generally, deep sea beds cause more data spread, resulting in decreased data density and thereby, decreases resolution.

Checks 

Depth range
Appropriate resolution
Format

Pass Requirements 

Depth range: Establish the deepest depth from the dataset. This is what will define the gridded resolution of the multibeam bathymetry data.
Appropriate Resolution: Before running the gridded multibeam bathymetry data through QAX, ensure the gridded resolution aligns with the D_d depth bands from Table 9 of the Australian multibeam guidelines (section 5.1.2.1). For example, if the deepest depth surveyed is 300 m, observe the higher resolution band, which in this case is 4 m. Run data through QAX to verify if the data passes.
Format: Ensure the multibeam bathymetry data is gridded as a 32-bit floating point Geotiff as defined in the AusSeabed product specifications.

Examples

Pass example

Description  

GA 4870 Ashmore Reef Marine Park Survey. 

Test results  

Depth range: Deepest depth is 854.3.
Appropriate resolution: 16 m, gridded resolution is 16 m.
Format: 32 bit floating point geotiff.

Pass 

Yes

Explanation  

This dataset meets the requirements outlined above and passes checks 1, 2 and 3.

Fail example

Description  

GA 0222 Austrea Bathymetry 1999. 

Test results  

Depth range: Deepest depth is ~5500.
Appropriate resolution: 128 m, Gridded resolution is 100 m.
Format: 32 bit floating point geotiff.

Pass 

No

Explanation  

This dataset does not meet the requirements outlined above as it fails check 2.