layout: default title: cutMVPLocationSections parent: Grid Tools nav_order: 17 —

cutMVPLocationSections

Description

cutMVPLocationSections is a specialized command-line utility designed to extract and combine vertical profile data along a specified X-location (column) from a series of images with corresponding MVP (Moving Vessel Profiler) data. It takes an MVP file, one or more image files (either 8-bit or float JHC grids), and an X-coordinate. It resamples the MVP data and extracts vertical slices from the image(s) at that X-location. The output is a single ASCII file containing combined depth, sound velocity, and image intensity values along the vertical section, suitable for further analysis or plotting.

Usage 

cutMVPLocationSections -mvpfile <mvp_file.m1> -outfile <output.ascii> -xloc <x_pixel_location> -allimages <image1> [image2 ...] [OPTIONS]

Arguments

Option Description Default / Example
-mvpfile <mvp_file.m1> Required. Specifies the path to the input MVP (Moving Vessel Profiler) data file, typically in an .m1 format. mvp_data.m1
-outfile <output.ascii> Required. Specifies the path for the output ASCII file. This file will contain the combined vertical profile data. vertical_section.txt
-xloc <x_pixel_location> Required. Specifies the X-coordinate (column index) in the image(s) from which to extract the vertical section. -xloc 7 (extracts from column 7)
-allimages <image1> [image2 ...] Required. Specifies one or more input image files. These can be either 8-bit or float JHC-format grid files (.8bit or .r4). Multiple image files can be provided. -allimages Reg_Sect.L034.018kHz.r4 Reg_Sect.L034.038kHz.r4
-zpix <value> Specifies the vertical pixel step value (e.g., in meters per pixel) used for resampling the MVP depth data. 1.0
-xwidth <value> Specifies the width in pixels around the -xloc to average image intensities, providing a smoothed profile. 1 (no averaging, single column)
-upcast Process only the upcast portion of the MVP profile.  
-downcast Process only the downcast portion of the MVP profile.  
-bothcast Process both upcast and downcast portions of the MVP profile. This is the default.  
-v Enable verbose output during processing.  

How It Works

  1. File Opening: Opens the MVP file, all input image files, and the output ASCII file.
  2. MVP Data Reading: Reads the MVP data from the specified file, extracting depth and sound velocity information.
  3. Image Data Reading: Reads the JHC_header from each input image file.
  4. Profile Extraction: For each vertical step (dz) from 0 to max_depth:
    • MVP Resampling: Interpolates the MVP data to get the sound velocity at the current depth.
    • Image Slice Extraction: For each input image, it extracts the pixel value (intensity) at the specified xloc and current depth. If xwidth is greater than 1, it averages pixels around xloc.
    • Writes the combined depth, sound velocity, and image intensities to the output ASCII file.

Output Files

  • <output.ascii>: An ASCII file containing combined depth, sound velocity, and image intensity values along the vertical section.

Dependencies

  • array.h: For JHC_header structure and image data handling.
  • support.h: For general utility functions and error handling.

Notes

This tool is particularly useful for creating cross-sectional views of oceanographic data, allowing for visual correlation between sound velocity profiles and acoustic imagery (e.g., from echosounders or sidescan). This can help identify scattering layers, thermoclines, or other water column features.