About transects

An Echoview transect

In hydroacoustic data analysis, a broad description of transects is the chosen time segments or vessel paths corresponding to sampling intended for analyses. This is opposed to when the recorded data serves other goals, such as calibration.

Hence, it is useful to demarcate transect segments in your data that are relevant to your specific goals. The transect feature in Echoview is an analysis domain that serves this purpose. Transects are defined by the following within a transect group:

  • ID
  • Name
  • Start time
  • Stop time
  • Notes

For details on each of the above, refer to the transect properties dialog box. Transects are defined in time to the 0.1 millisecond on the Details dialog box. Elsewhere onscreen transects are displayed to the nearest millisecond.

A ping is in a transect if its ping time is equal to or greater than the Start time and less than the Stop time of the transect. Only pings within a transect (in an assigned transect group) are used for analyses or in the Transect subset operator.

You can therefore use transects to isolate contiguous ping segments in your data for analyses. Transects do not affect the behavior of other Echoview variables. Since transects are defined by time, they are available to either mobile or fixed platforms.

Echoview's transect feature mainly supports single beam data. Transect support for multibeam data is restricted to creating transects and using the Transect subset operator to filter the pings in a transect (or invert the filter).

Refer to Using transects for more information about transects, including:

Transect groups

Transect groups are dataflow objects and act as containers for individual transects. You can customize the name and provide a description for any transect group with the Transect Group Properties dialog box.

You can only create transects within a transect group, and no two transects can overlap within a transect group.

To use the transects in a transect group assign that transect group to a platform.

While you can create multiple transect groups in an EV file, only one transect group can be assigned to a platform at a time. This means Echoview ignores all transects in unassigned transect groups.

Double-click on the transect group object in the Dataflow window to open the transect group table listing all the transects in that group.

Refer to Using transect groups for more information, including:

See also

Using transect groups
Using transects