rejectSounding

Description

rejectSounding is a command-line utility used to flag or eliminate multibeam soundings in OMG-HDCS merged files that fall outside specified depth or across-track range thresholds. It provides options to re-initialize beam statuses, mark entire swaths as bad, or even apply a scaling factor to problematic soundings.

This tool is useful for initial data cleaning, removing gross outliers, or isolating data within a particular spatial extent.

Usage 

rejectSounding <mergefile(s)> [OPTIONS]

Arguments

Option Description  
<mergefile(s)> Required. One or more paths to OMG-HDCS merged files to be processed. These files are modified in place unless -check is used.  
-v Enable verbose output.  
-eliminate Instead of just flagging, it completely zeros out the data for rejected beams.  
-check Runs the checks but does not write any changes to the file. Useful for previewing potential rejections.  
-divide10 For depths outside the specified range, it divides observedDepth, acrossTrack, and alongTrack by 10 (a specific hack).  
-newstart Resets the status of all valid beams to 0 (good) before applying new rejection criteria.  
-whole_swath If any beam in a profile is rejected, the status of all valid beams in that entire swath will be set to 22.  
-range <max_across_track_m> Specifies the maximum absolute across-track distance (in meters) a sounding can have. Beams beyond this range are flagged. 100000
-depths <min_depth_m> <max_depth_m> Specifies the minimum and maximum water depth (in meters) for valid soundings. Beams outside this range are flagged. 0 to 100000

How It Works

  1. File Processing: The tool iterates through each provided merged file.
  2. Summary Header Reading: Reads the summary header for basic file information.
  3. Profile and Beam Iteration: For each profile (ping) in the file, and then for each beam within that profile:
    • Status Initialization (-newstart): If -newstart is active, the status of each beam is reset to 0 if it has a valid observedDepth.
    • Range Check: Compares the absolute acrossTrack value (converted to meters) with maxrange. If it exceeds maxrange, the beam is marked for rejection.
    • Depth Check: Compares the observedDepth value (converted to meters) with mindepth and maxdepth. If it falls outside this range, the beam is marked for rejection.
    • Action on Rejection:
      • -divide10: If this option is used and a beam fails the depth check, its observedDepth, acrossTrack, and alongTrack values are divided by 10 (a specific, hardcoded scaling).
      • Flagging: Otherwise, if a beam is marked for rejection and its status is not already set, its status is set to 22 (a common flag for bad soundings).
      • -eliminate: If this option is active, the entire OMG_HDCS_beam structure for the rejected beam is zeroed out (effectively removing it).
    • -whole_swath: If this option is active and any beam in the current profile has been modified, then all valid beams in that profile will have their status set to 22.
  4. In-Place Update: If the -check flag is not used and any beams were modified or refreshed, the updated raw beam records are written back to the merged file.

Output Files

The input merged files are modified in-place (unless -check is used).

Dependencies

  • OMG_HDCS_jversion.h: For OMG-HDCS data structures.
  • support.h: For general utility functions and error handling.

Notes

rejectSounding is a versatile tool for initial data cleaning, allowing for rapid filtering of gross outliers or data outside the survey area. The -eliminate option permanently removes data, while simple flagging (22) allows for later review. As the tool modifies files in-place, backups are highly recommended. The -divide10 option is a specific “hack” for certain data anomalies.