Copyright © 1997-2008 Myriax Software Pty. Ltd.

Features of virtual echogram module

The "Virtual echogram" module is an advanced data processing module designed for applying mathematical operators to an entire echogram (variable) and displaying the results as a "virtual" echogram. Virtual echograms can be used as inputs to further operators to create powerful data analyses. Example operators are a "blur" operator to smooth (low pass filter) an echogram, a "minus" operator to subtract two echograms (producing a "dB difference") or a "resample" operator to calculate a lower resolution echogram. More advanced operations can be done using the "formula" operator which provides a simple enviroment to create custom mathematical and logical expressions for processing data.

There are many applications for virtual echograms including species classification and identification using 2 and 3 frequency techniques, echogram smoothing to improve fish school detection and background noise correction.

Like other modules this module will be developed continuously to keep up with new techniques in fisheries acoustics.
 

General

• Generalised tools for applying mathematical operators to echogram data.
• One hundred and twenty operators with user defined parameters.
• You can combine operators to create powerful new analyses.
• You can use operators to implement new techniques from the literature.

Example operators

• Arithmetic operators (eg echogram differencing).
• Bitmask operators (create masks and use logical operations).
• Conversion operators (eg convert logarithmic data to linear).
• Convolution operators (apply convolution filters and image processing using pre-set or user-defined kernels).
• Data manipulation operators (eg resample by distance interval).
• Imaging operators (eg overlay echograms).
• Movement operators (eg distance correction, GPS filter, GPS Kalman smoothing filter).
• Multibeam operators (require multibeam module - eg select a single beam for display as echogram).
• Single target detection operators for single beam and split beam data.
• Single target manipulation operators (eg find those single targets detected at the same range at 2 frequencies).

Example operations

• Background noise correction by subtraction.
• "dB difference" technique for species classification.
• View single targets overlaid on Sv echogram (to see ST positions in relation to echogram features).
• Smooth echogram prior to schools detection.
• Resample a large data set to compress display.
• Create conditional algorithms for species identification.
• Detect and correct bad pings and erroneous bottom detections.