About roll data
Roll data are records of the deviation of the platform from the horizontal in degrees with a valide range of [-180, 180]. A roll of 0 degrees indicates a horizontal platform.
Positive roll on a vessel in motion indicates starboard roll, that is the starboard side of the platform lowers and the port side rises.
Roll data can used with single beam data and multibeam data. Use roll data as an input operand with the:
- Motion correction (Dunford method) operator.
- Motion range bitmap operator.
- Multibeam roll at transducer operator.
Support for roll data may be discussed under your file format or file format's raw variables.
What is affected by roll data?
Roll data affects the transducer orientation only, not its position. Echoview currently assumes the position of the transducer and roll sensor to be at the center of platform motion. The transducer orientation for singlebeam virtual variables is unaffected. For more information refer to About transducer geometry: Pitch and roll.
Roll data will affect the orientation of the data in a multibeam variable and thus affect:
-
Display of Multibeam echograms
-
(Bottom) surface detection from multibeam echograms
-
3D school detection on multibeam echograms
-
Multibeam ping curtain creation from multibeam echograms
Note: The beam select operator will not function on roll corrected data. The Angle select operator is intended to replace it. See About Multibeam echograms for further information.
Roll data and pitch data will affect the position of data in a single beam virtual variable if the Motion correction operator is applied. This in turn, will affect biomass estimates that are derived from such a virtual variable.
See also
Exporting roll data
Roll graph
Roll data file format
Creating 3D objects
About pitch data