Data processing


Our research on mapping techniques has lead to several processing workflows for the generation of 2D and 3D photomosaics, sonar mosaics and bathymetries of high quality, accuracy and resolution.

Sonar mosaicing


Vehicle operations in underwater environments are often compromised by poor visibility conditions. The perception range of optical devices is heavily constrained in turbid waters, thus complicating navigation and mapping tasks in environments such as harbours, bays or rivers. A new generation of high-definition forward-looking sonars providing acoustic imagery at high frame rates have recently emerged as a promising alternative for working under these challenging conditions.
Our research on the topic has led to a complete mosaicing pipeline tailored to the characteristics of the forward-looking sonar imagery. By using a registration technique able to handle the low resolution, noise and artifacts associated with sonar image formation we compute motion constraints between different sonar frames. These pose constrains are then embedded inside a global alignment framework that can also integrate other sources of navigation data. This scheme enables the rendering of acoustic mosaics that:

  • Provide a consistent overview of the surveyed area regardless of the water visibility conditions.
  • Embrace large areas involving different vehicle tracklines.
  • Undergo both translational and rotational 2D motions.
  • Are applicable to a wide variety of environments, including those with a scarcity of features.
  • Do not require absolute positioning sensors and can potentially work on minimally instrumented vehicles.
  • Provide a significant improvement of the signal-to-noise ratio and resolution with respect to the individual sonar images.