GRASS Multibeam Import

Introduction

The r.in.mb GRASS/Mb-Stystem program is designed to import mbio compatible multibeam data directly into the GRASS GIS.
The program is a modified version of r.in.xyz. Instead of reading an ASCII XYZ file, r.in.mb reads an MB-System compatible list file as shown below.

/data1/MULTIBEAM_DATA/RAW2007/07_Pingos_JD245_RAW/0050_20070902_154139_Petrel.all 56 1.0
/data1/MULTIBEAM_DATA/RAW2007/07_Pingos_JD245_RAW/0051_20070902_155508_Petrel.all 56 1.0
/data1/MULTIBEAM_DATA/RAW2007/07_Pingos_JD245_RAW/0052_20070902_161050_Petrel.all 56 1.0

…

The r.in.mb program automatically projects the MB coordinates into the current GRASS coordinates. The program also does a simple in-fill (default = 3×3) on the imported GRASS raster. The in-fill routine is taken from the GRASS program r.grow.

The r.in.mb program uses the following new and changed command options from r.in.xyz:

Parameters:
input MB-System style list-file
width Restrict data by acrosstrack distance (Max)

Flags:
-a Use amplitude (default = bathymetry)
-s Use sidescan (default = bathymetry)

The percent option of r.in.mb (xyz) allows large datasets to be imported when system memory is restricted.

Example:

Step 1:
Create MB-System style data list.

Step 2:
Set GRASS region and resolution for importing multibeam data.

Step 3:
Import bathymetry using …
r.in.mb inp=datalist.mb-1 out=mb_bathy_raster
Import backscatter using …
r.in.mb -a inp=datalist.mb-1 out=mb_backscatter_raster

Building Source

1. Download the source code tarball here
2. Extract the tar file in GRASS(v.6) tree in raster directory.
3. Change to r.in.mb directory and edit the Makefile. Ensure the the LIBES and EXTRA_CFLAGS are set to the installed MB-System.
4. Run make to build programs.

ToDo

• Port program to GRASS v. 7.
• Improve coordinate handling. Program assumes multibeam data is in geographic coordinates and re-projects to current GRASS coordinates.
• Improve data in-filling routine.
• Add more gridding options such as beam restriction, weighted beams, etc.
• Add program to directly import multibeam navigation as GRASS vector (for setting region and showing coverage).
• Build stand-alone program that uses mbio and grids using something like the glib N-ary Tree. This would allow fast access to more complex gridding routines such as nearest neighbour.