7k2nav

Description

7k2nav is a utility designed to extract position data from Reson 7k (.s7k) files and convert it into a generic binary navigation file format (.nav). It specifically targets 7k_1003_Position records within the .s7k file, extracts the relevant timestamp, latitude, and longitude, and then writes them to a .nav file compatible with other OMG tools.

This tool is essential for providing position data for georeferencing multibeam sonar data when the .s7k file is the primary source of navigation.

Usage 

7k2nav -s7k <input_name> -omg <omg_file_prefix> [-v] [-debug]

Arguments

Option Description
-s7k <input_name> Required. Path to the input Reson 7k .s7k file.
-omg <omg_file_prefix> Required. Prefix for the output OMG-HDCS files. The tool will generate:
* <omg_file_prefix>.nav: Binary navigation file.  
-v Enable verbose output.
-debug Enable debug output.

How It Works

  1. Initialization: Parses command-line arguments to get input .s7k filename and output prefix. Initializes Reson 7k data structures (Reson_7K_Index, Reson_7K_DRF, Reson_7K_1003_Position) and jcu_nav_rec.
  2. File Opening: Creates the output navigation file (.nav).
  3. 7k Indexing: Calls build_Reson_7K_Index() (an external function) to create an index of all packet types within the .s7k file.
  4. Position Data Extraction: Iterates through each 7k_1003_Position record found in the .s7k index:
    • Seeks to the record’s file offset.
    • Reads the Reson_7K_DRF and Reson_7K_1003_Position data.
    • Calls convert_7K_position() (an external function) to convert the 7k position data into a jcu_nav_rec structure (nav_out).
    • Writes nav_out to the .nav file using nav_write() (an external function).
    • Increments num_nav_recs.
  5. Cleanup: Closes all open files.

Output Files

  • <omg_file_prefix>.nav: A binary file containing navigation records (jcu_nav_rec).