Removing turns in bathymetry and backscatter processing

[kjerram]

Adapted from email conversation between Shannon Hoy (NOAA) and Jonathan Beaudoin (HydroOctave Consulting) in Feb 2024.

Context: Survey files are not incremented during turns, leaving turn data in the files and complicating the 'standard' survey line processing.

Problem: The impacts of swaths in the turns are especially clear and problematic in backscatter mosaics (e.g., in FMGT).

Various solutions:

1. Mosaic editing: Remove turn data from mosaics in the backscatter processing software.

Pro: This does not require earlier processing or export to GSF; the raw data format can be used.

Con: Edits made to the mosaics are not carried through to other products (e.g., other mosaics at different resolutions). Also, the swath removal step in backscatter software may be less intuitive / more time-consuming than swath or navigation rejection in other packages (see below).

2. Swath editing: Remove turn data in bathymetry processing software (e.g., Qimera), export to GSF, and import into backscatter processing software (e.g., FMGT).

Pro: This provides the opportunity to address other bathymetric data quality issues (e.g., outlier removal) and carries the edit all the way through bathy and backscatter processing.

Con: This requires swath editing and export to GSF from another software package.

3. Navigation editing: Remove turn data by flagging / rejecting the corresponding heading data in the time series editor (e.g., in Qimera). This causes a navigation lookup failure during bathy processing that will reject the turning swaths and carry this through to GSF export.

Pro: may be much faster than swath editing; GSF carries these edits through all mosaics in the backscatter processing step.

Con: This requires navigation editing and export to GSF from another software package.

[JonathanBeaudoin]

Thanks for posting this, @kjerram . One fine tuning recommendation: The "Con" for option 3 should mention that this requires navigation editing, not swath editing.

[kjerram]

Good catch @JonathanBeaudoin - fixed!