What is affected by transducer geometry
Some display, export and other options in Echoview take transducer geometry into account and others do not. This page lists some common display and export options and describes whether or not they take transducer geometry into account. This page has the following sections:
Note: If you want to know whether transducer geometry is applied to a display or export option that is not listed on this page, contact Echoview support.
Exports
Many exports from Echoview include latitude and longitude values. The table below defines whether the exported values have been corrected for transducer geometry or are the latitude/longitude of the GPS antenna at time of ping.
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Export type |
Latitude/longitude values exported |
Implications |
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Data value exports (including Sv, TS, Angular position, underlying data) |
Latitude/longitude of GPS antenna at time of ping |
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Latitude/longitude of GPS antenna at time of ping. Latitude and longitude are corrected for transducer geometry. Altitude is calculated with respect to transducer location and geometry. |
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Latitude/longitude of GPS antenna at time of ping |
Exported depth is not at the exported latitude/longitude coordinates unless the transducer was located at the same point on the platform as the GPS antenna and was pointing straight down. |
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Analysis by regions and cells exports (including analysis by regions, cells, regions by cells) |
Latitude/longitude of GPS antenna at time of ping |
Exported region and cell start, middle and end latitude/ longitude are not at the real world coordinates unless the transducer was located at the same point on the platform as the GPS antenna and was pointing straight down. |
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Latitude/longitude of GPS antenna at time of ping |
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Latitude/longitude of GPS antenna at time of ping |
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Latitude/longitude, are corrected for transducer geometry, and are exported for:
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Single target exports are at real world coordinates. Distances based on Target_true_depth and Target_on_axis_depth are calculated using the WGS84 datum. See also Mapping: Target depth. |
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Latitude/longitude are corrected for target-based analysis variables in fish track analysis exports. Region-based analysis variables in fish track analysis exports are not corrected. This is likely to change in a future version of Echoview. |
Geographic positions of target-based analysis variables in fish track exports are at real world coordinates. Distances based on Target_true_depth and Target_on_axis_depth are calculated using the WGS84 datum. See also Mapping: Target depth. |
Construction and placement of 3D objects in a scene
The table below defines whether the data is used to construct 3D objects and place them in scenes is corrected for transducer geometry or is based on the latitude/longitude of the GPS antenna at time of ping.
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3D Object type |
Latitude/longitude data used in construction and placement of the 3D object |
Implications |
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Corrected for transducer geometry. Note: There is not a dynamic link between the 3D objects and transducer geometry settings, i.e. if you change the transducer geometry settings the 3D objects will not be updated automatically |
3D objects size, shape and position in the scene are based on real world coordinates. |
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Latitude/longitude of GPS antenna at time of ping. |
Surface properties and position in the scene will not represent real world coordinates unless the transducer was located at the same point on the platform as the GPS antenna and was pointing straight down. |
Graphs
3D single target graphs
On 3D Single target graphs showing multiple beams, transducer geometry is taken into account when drawing the beams.
Operators
Single target manipulation operators
Single target manipulation operators calculate distance between single targets using data that have been corrected for transducer geometry when comparing positions of single targets.
For further details refer to ST Difference, ST Intersection, ST Union.