Creating a GeoTIFF From an Online Basemap

Chesapeake Times, Vol 7 | October 2021

SonarWiz contains many individual capabilities. This alone makes it powerful software. These capabilities can be combined in various ways to extend that functionality. In this article I will go over one such use where I will configure an Online Basemap and then convert it to a GeoTIFF Basemap. 

In SonarWiz, a Basemap is a raster or vector map that is shown on the Plan View behind the sonar and other imagery. SonarWiz has many types of maps that it can use as a Basemap. The Online Basemap option will download the satellite image from an online database. While SonarWiz does store the map for offline use, it does not store it with your project. It will not open on another offline computer. In addition, it is more efficient and convenient to use a GeoTIFF as a Basemap.

Creating a GeoTIFF from a Basemap consists of 3 simple steps. Each one uses a different SonarWiz tool or capability. 

Add a Basemap

Using the Map Manager in SonarWiz I added a Basemap to the project using the online World Imagery source and selected to download the area within 1 mile of the Latitude/Longitude coordinates of the project. 

Create a Digitized Feature
SonarWiz has the ability to create highlighted areas we call Digitized Features. These can be used for many purposes. In this instance I used a rectangular Digitized Feature to outline the survey area by clicking and dragging the rectangle in the Plan View area. The rectangle size and orientation can be modified after it is initially created using the mouse.

Export the GeoTIFF
For this final step I used the Save Project as GeoImage tool to create a GeoTIFF that is cropped to the rectangular Digitized Feature. It makes it easy to only include the Basemap imagery that I need.  Usually the Save Project as GeoImage tool is used for exporting mosaicked sonar imagery. However, it can be used to export any data shown in the Plan View to a GeoTIFF file. This makes it useful for converting data of all kinds to GeoTIFF images which then can be used in SonarWiz or other software easily.

– Christopher Favreau, CTO