CUBE: The Combined Uncertainty and Bathymetry Estimator applies Bayesian statistics and modeling to multibeam data and provides uncertainty and depth estimations over a gridded surface.

CUBE Node: A bathymetric estimation point, including the uncer­tainties of estimation. CUBE calculations require a gridded surface. A Node is the center of one cell in the grid.

CUBE Grid: A regularly spaced grid of CUBE nodes encompass­ing the survey area.

Hypothesis: Each CUBE node has one or more depth hypothe­ses. In this context, a hypothesis is a set of soundings, consistent within themselves, leading to a reasonable depth estimate.

Multiple Depth Estimates: More than one depth estimate may exist within a node. Consider sounding over a school of fish; perhaps half the soundings are returned by the fish and the other half are bottom returns. Each set of soundings (depth estimation) is consistent within itself, but CUBE is constrained to choose only one.

Multiple Estimate Disambiguation: Choosing the correct depth estimate from 2 or more. Automatically done in CUBE by compari­son with surrounding nodes. Of course the user has the option of over-riding that selection.

Ratio: Indicator of the strength of the depth estimate, zero being best and 5 being worst.

Uncertainty: This is the 95% confidence level associated with each CUBE depth. It is a function of the variance of the soundings used in estimation.

TPU (Total Propagated Uncertainty) is a calculation of sounding uncertainty based on sonar, environmental and sensor (e.g., GPS) information. There are vertical and horizontal components of TPU: TVU and THU, respectively.