QA/QC and DTM production details
For each maritime region bathymetric survey data and aggregated bathymetry data sets have been collated from public and private organizations. These have been processed and quality controlled and used to produce a regional Digital Terrain Model (DTM).
The DTM has a grid size of .25 minute * .25 minute. Each grid cell has the following information:
- x,y coordinates
- minimum waterdepth in meters to LAT
- average waterdepth in meters to LAT
- maximum waterdepth in meters to LAT
- standard deviation of waterdepth in meters
- number of values used for interpolation over the grid cell
- number of elementary surfaces used to compute the average grid cell depth
- average waterdepth smoothed by means of a spline function in meters to LAT
- an indicator of the offsets between the average and smoothed waterdepth as a % of the waterdepth
- reference to the prevailing source of data with metadata.
Note: The water depth values are in meters with reference to LAT. Later on a transformation service will be provided to transform all values from LAT also to Mean Sea Level (MSL).
The DTM values have been determined from 3 possible sources of data:
- Bathymetric survey data = high resolution data sets from single and multibeam surveys that are referenced via the Common Data Index (CDI) metadata and service
- Digital Terrain Model data = composite data sets produced and delivered by a number of external data providers such as Hydrographic Offices derived from their internal bathymetric database and based upon historic surveys. The aggregated data sets are referenced with metadata documents
- GEBCO 30” gridded data, used to complete area coverage in case there are no survey data or composite data sets available to the partners.
It is accepted that the accuracy and precision of the gridded data will vary over the basins in question. No new data has or will be collected specifically for this project. In case of multiple survey data for a cell, all surveys will be used for the calculations after having filtered datasets not satisfying to the QA/QC criteria.