Qimera Cross Check

How to Start

  • Cross Check option from Tools menu of Main Menu bar

What it Does

Cross Check performs a statistical analysis of beam footprint values referenced to a selected Dynamic or Static Surface.

General Description

Cross Check requires at least one valid, processed, raw sonar or processed points file and one Dynamic or Static surface to run.  Simply select the line or lines you want to use to compute your statistics and the surface you wish to perform the statistics on.  The tool consists primarily of a statistics table and a plot area for various view of the data as described below.


For more information on navigating the data of the plot, see the section on Qimera Plot Surfaces.


Toolbar

  Zoom Out Button

If you have zoomed into an area of the plot, this button will zoom out to the extents of the data.

  Explore Mode

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.

  Zoom Mode

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.

Cross Check Menu

Reset Zoom

Reset zoom to extents of data.

Show Points

Show the sounding depth bias points for the scatter plot.

Show Mean

Show the mean depth bias line for the scatter plot.

Show Std. Dev Envelope

Show the standard deviation envelope for the scatter plot.

Show IHO Limits

Show the IHO limits (dashed lines) on any plot.

Export ASCII Statistics and Results Data...

Export the computed statistical data to an ASCII file.  This includes the contents shown in the lower right Statistics panel in the Cross Check main window.  This results data includes the the mean and standard deviation as binned by angle or beam number.  Exported mean and standard deviation respect the view controls for x-axis (beam angle or beam number) and y-axis (depth bias in survey units or in percentage of water depth).

Export ASCII Raw Difference Data...

Export the raw beam difference results data to an ASCII file.  This exports the point data shown in the main graph.  Exported data currently includes:

  1. Survey line number, matched to a list of survey file names in the header of the export file.
  2. Ping number, as assigned by the sonar.
  3. Beam number, counting from 1.
  4. Beam angle in degrees, positive to starboard
  5. Beam X (easting) in project units, e.g. meters or feet, etc.
  6. Beam Y (northing) in project units, e.g. meters or feet, etc.
  7. Beam Z (depth), in project units, e.g. meters or feet, etc.
  8. Grid Z, the depth reported in the user selected grid for the beam's location, in project units.
  9. Delta Z, difference between Beam Z and Grid Z, in project units
Export Plot Image

Export the plot to a JPEG or PNG image.


Plots

There are up to three graphical plots available depending on the type of data file that is selected for cross check. Raw files support all plot types. Processed point files only support the histogram plot due to the absence of beam angle information in some point formats. 

Scatter Plot

The scatter plot displays the individual footprint bias between the computed footprint Z and the reference surface Z. It also displays a mean bias line and an IHO envelope that is the mean bias +/- 1 standard deviation.  Finally it displays limit lines for the selection IHO order.  You can change the X-axis to be by beam angle or by beam number.  The Y-axis can be changed to show depth bias in survey units or depth bias as a percentage of water depth. 

Uncertainty Plot

The uncertainty plot will display depth uncertainties (scaled to 95% confidence level) as well as a dashed IHO limit line that graphically shows the limit that the uncertainties should not exceed.  You have the same X/Y axis options as you do for the scatter plot above.

Histogram Plot

This histogram plot shows the depth bias distribution of your data.


Statistics Computation

You can select the IHO order for computing statistics (Order 1, Order 2, Special Order) or you can select Custom and enter your own values for parameters A and B, these being the fixed and depth varying components of the standard IHO equation used to specify survey accuracy order.  When you change either the custom values or the Order level, the statistics will be automatically recomputed and your plot will update accordingly.


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