Qimera Coverage Extinction Plot
How to Start
- Coverage Extinction Plot option from Tools->Utilities menu of Main Menu bar
What it Does
This tool lets you assess the swath coverage capabilities of your multibeam system.
Data to fuel this type of plot usually consists of a set of survey lines running from the shallowest to deepest depth range of the system. As the depth increases, the outermost beams have a harder time picking up a detection and the coverage decreases until finally reaching a point where even the nadir beams can no longer detect the bottom. Having this type of capability is very handy during Sea Acceptance Trials since the surveyor can assess the system's swath coverage performance relative to the manufacturer's claimed specifications to ensure compliance. It also helps raise attention to noise limitation issues due to mechanical, acoustic or electrical sources of interference. Repeating these types of field trials before and after visits to ship yards can also catch problems early on since often times there are mechanical and electrical changes made during dry dock periods, and sometimes even modifications to the hull which can create flow noise problems. Many examples of this type of plot being used to assess and diagnose system health can be seen in the technical reports produced by the Multibeam Advisory Committee (MAC) on their website, http://mac.unols.org/reports.
The image above repeats the analysis of a Kongsberg EM710 data set done by the MAC during a sea trial aboard R/V Falkor (look for the 2014 report on this at the link above, specifically page 18). The graph indicates that the EM710 achieved maximum swath width at a depth of about 500-600 m, which is within expectation. Full extinction occurred near 2,000 m, which was also expected. As with all Qimera plotting widgets, the graph can be saved as a report quality PNG file with full markup of axes, etc.
For more information on navigating the data of the plot, see the section on Qimera Plot Surfaces.
Zoom Out Button
If you have zoomed into an area of the plot, this button will zoom out to the extents of the data.
This is the primary exploration mode of the tool. As you move your cursor over the plot, the label in the lower left of the window will update to show the X/Y axis values.
When in zoom mode, simply click and drag an area of the plot to zoom into. Or simply single click a location to zoom in a bit on it. Alt-click a location to zoom out a bit. Or hit the Home button to return to the full extents of the data. At any time, you can Shift-Click to drag the plot to a new location. This is especially useful when you are zoomed in.
Plot Point Size
Clicking this icon will change the point size drawn in the widget. If you click and hold the button, it will display a menu where you can select point sizes between Small and XX-Large. Simply clicking will cycle through all sizes.
Plot Color By
Clicking this icon will change the Color By mode of the points drawn in the widget. If you click and hold the button, it will display a menu where you can select the Color By option directly. The options for color by are Vessel, Line, System, Ping, Beam, Depth, Intensity, Horizontal TPU and Vertical TPU.
Save to Image
Saves the current plot to a PNG or JPEG file. The image will include all grid lines and annotations labels.
Show Grid Lines
This option will turn grid lines on/off in plot plot area.
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