inArea

Description

inArea is a command-line utility that checks whether one or more OMG-HDCS data files (merged files or GLORIA files) intersect with a specified geographic area of interest. It’s a spatial filtering tool that helps in selecting relevant data files based on their geographic coverage.

Usage 

inArea <datafile(s)> [-array <imagefile>] [OPTIONS]

Arguments

Option Description  
<datafile(s)> Required. One or more paths to OMG-HDCS merged files or GLORIA files to be checked for spatial intersection.  
-array <imagefile> Specifies a JHC image file (e.g., a map or mosaic) whose header defines the geographic area of interest. The tool reads the xmin, xmax, ymin, ymax from this header.  
-xyzlist <filename> Specifies an ASCII file containing a list of input filenames.  
-usebounds When used with merged files, this option leverages pre-computed “100-ping bounds” files (.100ping_bounds) to accelerate the intersection check. These files provide a spatial index for every 100 pings.  
-exact This flag is present in the USAGE string but its specific function in the current code’s intersection logic is not explicitly defined. It might imply a more rigorous intersection test.  
-v Enable verbose output.  

How It Works

  1. Define Area of Interest: The tool first establishes the geographic boundaries of the area of interest:
    • If -array is specified, it reads the header of the JHC image file to get xmin, xmax, ymin, ymax.
    • Otherwise, it relies on manually defined or hardcoded default bounds (though the interactive prompt is currently commented out in the source).
  2. File Iteration: For each input data file (specified on the command line or in -xyzlist):
    • File Opening: Opens the input data file.
    • Bounds Extraction:
      • If it’s an OMG-HDCS merged file, the tool reads its summary header to get the overall geographic bounds (minLat, maxLat, minLong, maxLong).
      • If -usebounds is active, it further checks the more detailed .100ping_bounds files.
      • If it’s a GLORIA file, it extracts geographic information from its headers.
    • Intersection Check: It then determines if these data file bounds overlap with the defined area of interest.
  3. Report: The tool prints a message to standard output for each input file, indicating whether it intersects the specified area.

Output Files

The tool primarily outputs messages to standard output. No specific output files are generated.

Dependencies

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

Notes

This tool is useful for batch processing of large datasets where only data within a specific geographic region is relevant. The -usebounds option significantly speeds up the process for merged files by leveraging pre-computed spatial indices. The -exact option is present in usage but its functionality is not explicitly defined in the current code.