Advanced data processing options

Advanced data processing options should be used carefully. Please make sure that you fully understand what you are doing before altering these settings. In some cases, our support staff can instruct you to change one of these settings, if your data processing job fails with the current (default) settings.

Advanced data processing options are mainly used when converting raw data into soundings, but a couple of values are used in other tools as well (for instance: matrix generation). To open the "Advanced Data Processing Options" settings dialog, select the "Preferences..." option from the "Options" item in the top (main) menu bar. A collection of tabs with settings will appear, next, select the 'Miscellaneous' tab and click the "Setup..." button in the "Advanced Data Processing Options" section of the tab (located at the bottom of the tab).

Click the "Setup..." button in the "Advanced Data Processing Options"
section of the "Miscellaneous" tab.

Restore Defaults

After modifying one of the advanced data processing options, you can always reset the settings to their default values by clicking the "Restore Defaults" button. A confirmation box will appear, asking you whether you want to overwrite your changes. Click "Yes" and then "OK" to store the default settings.

Click the "Restore Defaults..." button to load the default settings.

Raw data file processing options

These options only apply to the generation of sounding files from recorded raw data files in the "Sounding Wizard". The options are mainly used to limit the maximum gaps between data, the maximum number of records per sounding and the least required GNSS quality when processing position and tide data. This option is only present in Hydromagic Survey since it does not apply to Hydromagic Dredging.

Maximum gap between position records

When your GNSS signal is lost for some time, Hydromagic will interpolate the positions between the closest position fixes (dead reckoning). The more time elapses, the more inaccurate the calculated positions and elevations will be. Using this setting, you can limit the time that calculated positions will be used. When this time has been exceeded, position data will be discarded, resulting in (small) gaps in the generated soundings. When you have a stable GNSS signal with an update of at least 1Hz, and with this setting set to 2 seconds, you should be fine in most cases.

Maximum gap between depth records

When depth values are missing, for instance when the sounder was unable to digitize the depth from the returning ping, gaps may be present in your raw data file. By default Hydromagic will interpolate the depths between the two closest measurements from the timestamp of the missing sounding. Using this value, you can limit the time that calculated depths will be used. When this time has been exceeded, depth data will be discarded, resulting in (small) gaps in the generated soundings.

Maximum gap between motion sensor records

When motion sensor records are missing, you might want to check your motion sensor first, as the data might be delayed (slow PC), or there might be a wiring problem. Using this setting you can set the maximum allowed gap in this data, but since motion data is updated so frequently, it might sometimes be better to completely remove the motion data when a problem occurs. To remove all motion sensor data, use the "Table Editor" in the "Sounding Wizard".

Maximum gap between sub bottom data records

Basically the same as for depth records, however since this value is less important, you can enter an alternate maximum allowed data gap here.

Maximum number of records per sounding file

Limits the number of records written to a sounding file. This function makes sure sounding files aren't getting too big which can cause processing soundings to be slow. It is recommended to split your survey into multiple raw data files to avoid this (for instance one raw data file per cross section). When your generated sounding exceeds this limit, you might want to increase the data interval of the sounding in the "Sounding Wizard".

Minimum GNSS fix quality for tide processing

When calculating the current tide value from the elevation reported by your GNSS receiver, Hydromagic checks whether the position quality is "RTK Fixed", if not, the elevation value is considered to inaccurate to calculate the tide level. In some cases you might want to override this setting, for instance when the GNSS quality hasn't been reported since you are importing position data from a file format which does not include the GNSS quality information, or when the GNSS receiver sporadically looses RTK Fix. Please note that the longer the RTK Fix has been lost, the more inaccurate the data will become.

In cases where you imported the data from a data file using the "Raw Data Import Wizard", set this value to either "Unknown" or "Autonomous". When your raw data sometimes reported "RTK Float" or "DIFF" as GNSS quality, select this value. However when the RTK Fix status is lost for multiple seconds, you might want to sort out this issue on the hardware side first.

Raw data file advanced data processing options section.

GNSS Leap Seconds

UTC, or Coordinated Universal Time, is a global time standard that synchronizes clocks worldwide. It is based on the primary time standard, the atomic clock, and is periodically adjusted to account for the Earth's irregular rotation.

Although UTC and GPS are used for time synchronization, they are not the same. UTC is a global time standard based on atomic clocks, while GPS is a navigation system that relies on satellites to provide accurate time information. Other than UTC, GPS time (also known as GPST) is based on the frequency of atomic clocks on GPS satellites.

To synchronize UTC and GPS, a process called leap seconds is used. Leap seconds are added periodically to UTC to keep it in sync with the Earth's rotation. However, GPS time does not take leap seconds into account, meaning there is a constant offset between GPS time and UTC. Currently the offset from UTC to GPS is 18 seconds. This is important to know when using GPS Time in PPK correction files.

When performing PPK processing with correction files using GPS
time, make sure the leap seconds value is correct.

Matrix generation options

This settings apply to most tools where a matrix file is generated:

• Generation of matrix files from one or more soundings;
• Generation of matrix files from cross sections with elevation info;
• Generation of matrix files from vector charts (DXF);
• Generation of matrix files from various matrices;

Maximum distance from boundary

Defines the maximum distance of a point outside the selected boundary or boundaries, to be included in the matrix generation. When a sounding (depth value) is further away from the boundary, it will be ignored.

Maximum triangle diameter

When generating a matrix, all soundings will be connected using triangles. This is also called triangulation or a TIN model. This setting checks the maximum radius for the generated triangles and removes triangles which exceed the maximum setting (they contain the least accurate data).

Remove triangles which cross boundaries

When a triangle crosses one or more boundary lines (for instance an island) it will be ignored. Although this is an experimental function, it should be useful when you have islands.

Matrix generation advanced data processing options section.

Projection File Format

When data is exported for use in other applications, or when maps are downloaded, a projection file is automatically created. By default this is written in EPSG WKT format. However, in some situations the software in which the data is imported expects a different format. This option allows you to choose the projection file format used. It is recommended not to change this setting, or at least not for longer than during the data export.

The software supports the following projection file formats:

• WKT (EPSG) - Default value;
• PrettyWKT (EPGS);
• WKT (ESRI);
• PrettyWKT (ESRI);
• Proj.4;
• MapInfo;
• XML;

This option allows you to choose the projection file format used.

Bottom classification offsets

This function allows you to enter an offset for bottom loss for high and low frequency. This function is only available for sounders that return bottom loss information, like the Unabara Hydro-2F. The values can be entered after such a plugin has been loaded. Enter the values in decibel, the corrections will be applied in the "Sounding Wizard" when converting the raw data to soundings.

Bottom classification advanced data processing options section.