|Title||How to improve the quality and the reproducibility for acoustic seafloor characterization|
|Download||Download (whole publication) |
|Author||Masetti, G; Calder, B R; Mayer, L A|
|Source||Program and abstracts: 2017 GeoHab Conference, Dartmouth, Nova Scotia, Canada; by Todd, B J; Brown, C J; Lacharité, M; Gazzola, V; McCormack, E; Geological Survey of Canada, Open File 8295, 2017 p. 82,
https://doi.org/10.4095/305890 (Open Access)|
|Publisher||Natural Resources Canada|
|Meeting||2017 GeoHab: Marine Geological and Biological Habitat Mapping; Dartmouth, NS; CA; May 1-4, 2017|
|Related||This publication is contained in Todd, B J; Brown, C J;
Lacharité, M; Gazzola, V; McCormack, E; (2017). Program and abstracts: 2017 GeoHab Conference, Dartmouth, Nova Scotia, Canada, Geological Survey of Canada, Open File 8295|
|Subjects||marine geology; surficial geology/geomorphology; environmental geology; geophysics; mapping techniques; oceanography; marine environments; coastal studies; conservation; marine organisms; marine
ecology; resource management; biological communities; environmental studies; ecosystems; geophysical interpretations; acoustic surveys, marine; seafloor topography; bedforms; geological mapping; geological mapping techniques; biology; habitat
mapping; habitat conservation; habitat management; data processing; algorithms|
|Program||Ocean Management Geoscience, Offshore Geoscience|
|Released||2017 09 26|
|Abstract||Current commercial solutions for processing acoustic data with the aim of seafloor characterization does not take full advantage of the wide spectra of information collected by modern sonars (e.g.,
water column data, multiple sectors). In addition, those solutions tend to act as a 'magic black-box' with only a few user-defined parameters. This can be seen as an advantage (it makes these technologies available to a large community), but it also
engenders a lack of data reproducibility. Currently, it is a real challenge to 'properly' merge backscatter-based products from different vendors (and even from the same vendor given the lack of metadata). |
In order to mitigate both issues, we
developed a different approach. The proposed workflow is organized into two main phases: the first part focuses on artifact identification and reduction, while the second part is product-oriented. The artifact-oriented phase applies a (growing) set
of algorithms to facilitate the identification of corrupted data so that they can then be ignored or, if required by the user, reconstructed using several different techniques. This approach also provides a metric that can then be used to identify
which ping should be excluded during seafloor characterization.
The first phase is cleanly separated from the product creation. At the end of it, corrected data in the sonar's native format are generated together with an (optional) 'difference'
file (containing only the data that has been modified) and a human-readable and computer-interpretable textual description of all the applied processes. This 'native-format' solution is better than converting the data to a hybrid generic data format
which may not adequately preserve all of the important information from the file. The 'difference' files reduce the amount of data storage since they contain only the changes, rather than doubling the storage requirement. An additional advantage is
modularity. For instance, based on the kind of survey different strategies combining the identification and reduction methods can be built. Once the valid, corrected data files are created, they can be mosaicked or analyzed for seafloor
characterization by the user-preferred application.
The proposed approach is demonstrated with real-world data by first using a set of bubble washdown detection algorithms, then improving the quality of the generated outputs. Specifically, the
mosaic is created after the reconstruction of the corrupted samples with a weighted randomization schema, while the seafloor characterization is improved by ignoring the corrupted data.
A possible future development of this approach is to carry
all the line-based descriptions of the applied processes together with the products. To make this possible in a robust way, we propose the creation of an open, community-driven product data format mimicking what has been done for bathymetric data by
the Open Navigation Surface Working Group (BAG format).