deOuterMistrack

Description

deOuterMistrack is a utility designed to detect and flag “mistracked” soundings in the outer portions of multibeam sonar swaths, particularly observed in data from systems like EM2040C and EM712. These mistracks manifest as spurious detections beyond the coherent outer edges of the swath.

The tool identifies regions of the outer swath where Q_factor (quality factor) is -128 (indicating no detection) to determine the effective swath edge, and then flags any detected soundings (!beams[i].status) beyond this edge.

Usage 

deOuterMistrack <mergefile(s)> [-v] [-first <ping_num>] [-last <ping_num>]

Arguments

Option Description  
<mergefile(s)> Required. One or more paths to OMG-HDCS merged files to be processed. These files are modified in place.  
-v Enable verbose output.  
-first <ping_num> Specifies the starting ping number (inclusive) to process. All pings
-last <ping_num> Specifies the ending ping number (inclusive) to process. All pings

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. Ping Iteration: Loops through profiles (pings) from first to last (or all profiles if not specified):
    • Reads the raw beams for the current ping.
    • Determine Swath Edges:
      • It defines outer as no_beams / 8.
      • port_edge starts at outer and moves inward until a beam with Q_factor != -128 is found.
      • stbd_edge starts at no_beams - outer and moves outward until a beam with Q_factor != -128 is found.
      • These port_edge and stbd_edge values roughly delineate the coherent edges of the swath.
    • Flag Mistracks:
      • It then iterates from the determined port_edge inward towards the center of the swath. If a beam i in this region has !beams[i].status (meaning it’s currently considered valid) it flags it by setting the 5th bit of its status field (beams[i].status |= 1 << 5;). This marks it as a mistrack.
      • Similarly, it iterates from the stbd_edge outward and flags valid beams in that region as mistracks.
  4. In-Place Update: The modified beams (with updated status flags for mistracks) are written back to the merged file for the current ping.

Output Files

The input merged files are modified in-place.

Dependencies

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

Notes

Mistracks in the outer swath can be difficult to automatically filter using traditional slope-based methods because they might not represent sharp discontinuities. This tool uses a heuristic based on the Q_factor to identify these specific artifacts, which are common in newer multibeam systems. The status flag is updated using a bitwise OR, preserving other flags that might already be set.