The effect of slope and vessel speed on the performance of a single beam acoustic seabed classification system

Acoustic detection of a scallop bed from a single-beam echosounder in the St. Lawrence

“…At the end of the procedure, echoes with similar characters formed clusters that defined acoustic classes, which were mapped throughout the surveyed seabed. In addition, as the QTC classification accuracy can be affected by slopes (von Szalay and McConnaughey, 2002), data records corresponding to steep and moderate slopes at the margin of the study area were trimmed off before the analysis. The analysis was also done with all data and the resulting patterns (not shown here) pointed to similar conclusions.…”

“…In our case, however, no correlations between sediments or spatial patterns of communities and depth were found in the ground-truth data. Von Szalay and McConnaughey (2002) have shown that even modest bottom slopes could greatly affect the QTC performance. We removed all the data located on steep and moderate slopes from our initial QTC VIEW IV and QTC VIEW V data sets, but the resulting new QTC classifications were still dependent on depth.…”

“…However, Preston (2003) asserted that the QTC IMPACT resampling process to standardize echo duration removes the dependence on depth. Though this may help to align echoes with angles of incidence, the problem of the footprint increasing with depth still remains when the transducer is fixed on the vessel for any acoustic systems, as noted by Morrison et al (2001) andvon Szalay andMcConnaughey (2002). The QTC process averages the backscatter signal of five consecutive pings to generate a single-record to reduce ping-to-ping variability that may cloak sediment contribution to the echo (Preston et al, 2004).…”

“…These three Q-values are plotted in three-dimensional Q-space and then run through a cluster analysis to distinguish acoustically distinct bottom types. The QTC VIEW classification accuracy has been shown to be greatly affected by bottom slopes exceeding approximately 5e8 ( (von Szalay and McConnaughey, 2002). According to Hamilton et al (1999), QTC VIEW appears to be the more consistent and reliable of the two systems.…”

Real-time echosounder based acoustic seabed segmentation with two first echo parameters

“…Acoustic seabed classification is typically very successful for smooth horizontal seabeds. Problems are encountered over areas of variable bathymetry (or variable slope) (Hamilton et al, 1999;von Szalay and McConnaughey, 2002;Biffard et al, 2005), potentially leading to ambiguities or errors in seabed segmentation.…”