Multibeam Sponsors

Welcomes you to the Icebreaker Party

Grid Models versus TIN (Triangulated Irregular Network): Geometric Accuracy of Multibeam Data Processing

Alain DE WULF, Denis CONSTALES, Timothy NUTTENS, Cornelis STAL
Multibeam echosounder measurements serve to make a digital terrain model of the seafloor. The Delaunay triangulation is a widely appreciated and investigated mathematical model to represent the seafloor topography and is highly efficient for building triangular irregular networks (TINs) out of non-homogeneous data such as raw multibeam data.
Obtaining an accurate model of the seafloor is a major concern in dredging works. Contemporary hydrographical surveying tools, especially the multibeam echosounder, yield a very dense sampling of the seafloor. Consequently, this immense amount of data needs to be processed to generate an accurate terrain model, according to time and accuracy constraints imposed by the client. Modeling can be carried out in post-processing or in real-time, performing a real-time accountability which keeps track of the “cut” or “fill” volume changes realized at that moment. Most multibeam systems deliver equidistant interpolated data, allowing faster processing to be achieved by using equidistant grid modeling.
Both modeling techniques (TIN and grid) yield their own advantages and drawbacks. More specifically, the filtering options of TIN and grid models are quite different. In this paper, the accuracy, mathematically derived on a thorough statistical basis, of both grid and TIN models will be worked out and tested on large real-world bathymetric samples. The influence of different variables of the equidistant grid model (grid equidistance interval, computation methods of the grid cell height, interpolation method of the gaps in the grid model,…) will be taken into account.