The following information is a technical article about how to deal with R2Sonic Backscatter Processing in particulars with FMGT and related software.
TruePix provides a sidescan-like data set that provides more or less the same image quality as snippets, but takes less disk space than snippets. It also provides a time-series of angles at the same sampling interval as the intensity time-series. Effectively, it provides a data stream that is equivalent to an interferometric sidescan's output. This also means that the angular data needs significant filtering in order to be used for georeferencing of samples.
If you must process TruePix, you would import an XTF from QINSy (see notes in QINSy section above). You would need to set a "Custom Override" in the processing parameters to force the sensor type and you may need to adjust the Head dB bias to get the data into a reasonable signal range (-70 dB to +10 dB). Mosaics made from this would suffer from:
- Flat seafloor assumption georeferencing limitations common to all sidescan systems
- Potential signal level artifacts associated with variations in sonar settings by the operator (e.g. power, pulse and gain changes)
Notes from R2Sonic about configuring Hypack with R2Sonic systems
- Hypack has check boxes in sonar setup in Hypack hardware setup, one for TruePix, one for snippets. The fact that there are two checkboxes and not two radio buttons implies that it can do both, however R2Sonic's experience in Hypack 2016 and 2017 that it only records TruePix when both are checked.
- If you enable both in Sonic Controller to output but snippets and TruePix, Hypack will only record TruePix.
- R2Sonic's recommended configuration: only enable snippets in Hypack and only enable snippets output in Sonic Controller.
- In Hypack, change the time zone of the PC to UTC. Otherwise, you can get local time in HSX but the R2S files are in UTC as per the ZDA time-sync coming into the sonar.