Real Time Side Scan and Sub-bottom Navigation Improvements

Chesapeake Times, Vol 10 | July 2022

Improvements in SonarWiz sometimes occur mostly under the hood.  These changes alter the way SonarWiz works without changing the way SonarWiz presents itself to the user.  This article details some important changes to how SonarWiz works internally regarding real time navigation data.

Previously, SonarWiz would record the navigation data in the real time data files, CSF and XTF or SEGY.   When a user would adjust the position of the sonar using layback, the modified position was saved in the files as well.  The original position was not saved thereby making it difficult to readjust the position in post processing.  Generally, this involved re-importing the original files if there were any.   Not impossible but quite a bit of work.  We generally recommended that the layback be applied in post processing only.  This would allow the user to readjust the layback as many times as needed as the original navigation source position is retained in post processing.

After requests from our customers and CTI support staff we scheduled improvements for development for SonarWiz V7.09.03.  When we first started the development effort we did a code review.  It showed us that most of the pieces were available, we just needed to connect the pieces together.  We also found that we could benefit from some code cleanup and simplification in this area of SonarWiz.  The main goal of this development effort would be to give SonarWiz the ability to record the original position data along with the modified sonar position.   It was also important to tie this into all the post-processing file properties that are available for viewing and adjusting the sonar position.

Since most of the changes are internal, let’s take this opportunity to go over the main areas that contribute to real time navigation for SonarWiz.  The Coordinate Source controls which source the incoming position is taken from.   Some navigation input sources have a separate ship and sonar position.   The coordinate source choice tells SonarWiz which one will be used.  The project Coordinate System is also configured in the same Project Settings window.

The Navigation Input Setup configures where SonarWiz will get the navigation data from.  If Enable Nav IO is checked then the navigation data in the specified format will be received on the configured interface.  If Enable Nav IO is unchecked then the navigation data can come from the real time server.   The other important item to note is the Input Coordinate System.   SonarWiz can translate between the incoming position’s coordinate system and the project’s coordinate system.

Finally, the Layback Settings (shown at the beginning of this article) allows the user to change the Sheave Offset and Cable Out settings to allow SonarWiz to calculate the Layback as the navigation and sonar data are being received.

For more information about this capability the real time navigation and layback settings have been extensively documented in our SonarWiz user manual and is included with your SonarWiz installation.