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Preferred Format | Specifications | |
Level | Bathymetry | |
L3 |
Priority 1 32-bit floating point GeoTIFF (.tiff)
BAG single-resolution
Priority 2 BAG multi-resolution, LAS/LAZ |
Bathymetry and Backscatter Vertical datums: Ellipsoid and MSL Resolution as per Table 3 Variable: coordinates, depth (m neg value) or intensity (dB), density (sounding/cell), uncertainty, flag (bathymetry in GeoTIFF format requires three separate files: depth, density, uncertainty Coordinate system: Geographic WGS84 or GDA2020 Precision: Metric variables with minimum of 2 decimals, Angular variables deg with 6 decimals Navigation and Ancillaries Date and Time: Calendar and UTC or specify otherwise. Coordinate system: Geographic WGS84 or GDA2020 with an ellipsoid height datum. |
Table 108. Preferred L3 formats.
BAG
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CUBE algorithm is highly recommended to produce bathymetry surface unless it is not possible/available. When generating bathymetric surfaces, seabed depths dictate the grid resolution. Grid resolution is determined by AusSeabed depth bands (Table 3). Typically, a single grid is made for a survey, but we also accept multiple grids. It is required that the bathymetry grid(s) extends from the start and end port of the survey (port to port).
Table 39. AusSeabed depth bands and associated grid resolutions. Modified from NOAA (2019)
Normal depth band (≤45°) | Steep slope depth band (>45°)1 | Res (m) | Ratio2 | ||||
Ds (m) | Dd (m) | Range Interval (m) | Ds (m) | Dd (m) | Range Interval (m) | ||
0 | 20 | 20 | 0 | 20 | 20 | 0.5 | 0.0250 |
18 | 40 | 22 | 16 | 40 | 24 | 1 | 0.0250 |
36 | 80 | 44 | 32 | 80 | 48 | 2 | 0.0250 |
72 | 160 | 88 | 64 | 160 | 96 | 4 | 0.0250 |
144 | 320 | 176 | 128 | 320 | 192 | 8 | 0.0250 |
288 | 640 | 352 | 256 | 640 | 384 | 16 | 0.0250 |
576 | 1280 | 704 | 512 | 1280 | 768 | 32 | 0.0250 |
1152 | 2560 | 1408 | 1024 | 2560 | 1536 | 64 | 0.0250 |
2304 | 5120 | 2816 | 2048 | 5120 | 3072 | 128 | 0.0250 |
4608 | 12000 | 7392 | 4096 | 12000 | 7904 | 210 | 0.01753 |
1In cases of steep slopes, the overlap between grids of different resolutions may need to be increased to prevent gaps in their junction. In these cases, the coarser resolution grid should have its shoaler extent modified to prevent this coverage gap. 2Highest resolution at which the dataset can support a minimum of five soundings per node (ideally, twice the maximum standard required survey resolution for the depth of the area, i.e. 2.5% water depth) (NOAA, 2019). 3Based on 1⁰ beamwidth (highest resolution that the current technology of shipborne systems can effort) because of the constraint in the minimum capture distance in CUBE to a maximum of 100.
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