My Tickets

Qinsy

Height 3D -RTK- Settings

When using an accurate GNSS system, the following settings should be used in Database Setup and in the Computation Setup of the Controller.

The pictures that are displayed are only examples, settings may vary world wide.

Database Setup settings

Since Height aiding is not used in purely 3D accurate positioning there is no need to define a Mean Water Level Model.
Define the (Vertical) Datum parameters using the Geodetic Set-up wizard.

Note that once the template database is saved and reopened the MWLM fields on Page 1 of the wizard have been filled in with values entered for the Chart/Vertical Datum.


Define the Positioning System, and the Receiver Positions in the Driver Setup.

Make sure you know what coordinate reference system is used for the horizontal and vertical Receiver position components; it may not always be WGS84.

Define the exact locations of all sensors relative to the CoG.

Define the Height above draft reference (HADR).
In strict 3D accurate positioning this value is not used in the computation and can be left at zero.
However, if working with a towed object or ROV that is providing depth relative to water level, you will need to:

  1. Enter an HADR value.
  2. Define an underwater sensor system ('Draft' observation) on the surface object.
  3. Define an underwater sensor system ('ROV Depth' observation) on the sub-surface object.

Computation Setup settings

Set the Height status of the positioning system in the Computation Setup to "Accurate"

Set the correct Height priority for heave sensors (only in case of a redundant system).

Return to: top of page.

Return to: How-to Height - Tide and RTK

Example 3D Positioning - Accurate Height Status

Vessel Only

No height aiding is used when a vessel is positioned using an accurate positioning system, e.g. RTK.

Return to: top of page.

Return to: How-to Height - Tide and RTK

Vessel + Towed Fish

Height aiding is used when a vessel is positioned using an accurate positioning system, e.g. RTK, and a towed fish (or ROV) has a depth observation referenced to water level..




Changing the height status to Unreliable without changing any other settings gives:


    Delta Ht. CoG = Accurate Height - Unreliable Height = 1.90 - (-2.61) = +4.51 (as shown in the HAD window with Height Status = Accurate)

    Delta Ht. Fish = Accurate Height - Unreliable Height = -4.75 - (-9.96) = +5.21 (as shown in the HAD window with Height Status = Accurate)


Return to top of page.

Return to How-to Height - Tide and RTK

Generic Display Parameters

ParameterDescription

Comment

User-defined free text

Time

Update time (UTC) of the height aided observation

Vessel Name

Name of the vessel (object), as entered in Db Setup

Height

Value in survey units of the Height Aided Observation, which is calculated by the Height Aiding driver.
Note that the Driver is always present in the windows task bar irrespective of the Height Status (Accurate or Unreliable) selected.

The Height value is by default referenced to the Vertical Datum (also known as Chart Datum), but, alternatively, either Survey Datum or datums like WGS84, ETRS or ITRF (which all use the GRS 1980 ellipsoid) may be selected.

Notice that this value is the same as the height of the reference node for the selected vessel.

Datum:

  • Survey Datum
    Height value is referenced to the selected survey datum ellipsoid, e.g ED50.
    Survey datum is set in the template Database Setup, Geodetic Parameters, 'Output Datum Parameters' Wizard page.
  • WGS84/ITRF/ETRF
    Height value is referenced to the WGS'84 datum.
    Notice that WGS84 must be one of the two selected datums in the template Database Setup, Geodetic Parameters, 1st Wizard page
  • Vertical Datum (default)
    Height value is referenced to the selected vertical datum e.g NAP, De Min Geoid.
    Vertical datum (or Chart Datum) is set in the template Database Setup, Geodetic Parameters, 'Output Datum Parameters' Wizard page

Height Status

Two possible values: one or zero.

0:    The height aided observation is not used in any of the computations: The height status of the triggering system (located on the selected vessel) is set to Accurate in all available computations.

1:    The height aided observation is used in at least one of the computations. I.e. that the height status of the triggering system (located on the selected vessel) is set to Unreliable in one of the computations.

Height Sd

1 Sigma (68%) A-Priori Standard deviation of the Height Aiding observation

HeaveHeave component of the Height Aided Observation.
Heave Status

Two possible values:
1: Heave component is part of the height aided observation
0:  No heave component, or no height aided observation at all

Squat

Squat component of the Height Aided Observation.

Squat Status

Two possible values:
1: Squat component is part of the height aided observation
0:  No squat component, or no height aided observation at all

Draft

Draft component of the Height Aided Observation.

Draft Status

Two possible values:
1: Draft component is part of the height aided observation
0:  No draft component, or no height aided observation at all

Tide

Tide component of the Height Aided Observation.

Notice that this item is the same as item Tide under Tide Results

Tide Status

Two possible values:
1: Tide component is part of the height aided observation
0:  No tide component, or no height aided observation at all

Notice that this item is the same as item Tide Status under Tide Results

MWL Model

Mean Water Level Model component (often known as Mean Sea Level) of the Height Aided Observation.

MWL Model Status

Two possible values:
1: MWL (Mean Water Level) Model component is part of the height aided observation
0:  No MWL Model defined (in Db Setup), or no height aided observation at all

Depth

ROV Depth component of the Height Aided Observation.

Depth Status

Two possible values:
1: ROV Depth component is part of the height aided observation
0:  No depth component, or no height aided observation at all

Actual Water Level

The actual water level above Survey Datum

For the object's reference node the "Height above Actual Water level"  value is used minus the "Height above Survey/WGS84/Vertical Datum" value.

Mean Actual Water Level

The Actual Water Level (see above) minus the heave of the object, so i.e. the actual water level without the swell influence.

Datum:

  • Survey Datum
    Height value is referenced to the selected survey datum ellipsoid, e.g ED50.
    Survey datum is set in the template Database Setup, Geodetic Parameters, 'Output Datum Parameters' Wizard page.
  • WGS84/ITRF/ETRF
    Height value is referenced to the WGS'84 datum.
    Notice that WGS84 must be one of the two selected datums in the template Database Setup, Geodetic Parameters, 1st Wizard page
  • Vertical Datum (default)
    Height value is referenced to the selected vertical datum e.g NAP, De Min Geoid.
    Vertical datum (or Chart Datum) is set in the template Database Setup, Geodetic Parameters, 'Output Datum Parameters' Wizard page
Mean Water Level

The Actual Water Level (see above) minus the heave of the object (swell) and minus the tide.

Datum:

  • Survey Datum
    Height value is referenced to the selected survey datum ellipsoid, e.g ED50.
    Survey datum is set in the template Database Setup, Geodetic Parameters, 'Output Datum Parameters' Wizard page.
  • WGS84/ITRF/ETRF
    Height value is referenced to the WGS'84 datum.
    Notice that WGS84 must be one of the two selected datums in the template Database Setup, Geodetic Parameters, 1st Wizard page
  • Vertical Datum (default)
    Height value is referenced to the selected vertical datum e.g NAP, De Min Geoid.
    Vertical datum (or Chart Datum) is set in the template Database Setup, Geodetic Parameters, 'Output Datum Parameters' Wizard page

MWL Geoid Height

The current geoid height above survey datum, i.e. geoidal separation.
This is the calculated height value for the vessel location from the Mean Water Level model. This model is selected in your template setup on the first page of the Geodetic Wizard (Datum Parameters, Mean Water Level Model) using the first combo box. Normally you select your Mean Sea Level model there.

MWL Level Height

The current level height above geoid datum.
This is the calculated height value for the vessel location from the Mean Water Level model. This model is selected in your template setup on the first page of the Geodetic Wizard (Datum Parameters, Mean Water Level Model) using the second combobox. Normally you select your River Lines model there.

MWL Height Offset

The height offset above level datum.
This is a fixed offset value as entered in your template setup on the first page of the Geodetic Wizard (Datum Parameters, Mean Water Level Model).



Notice that this item is actually the same item as "MWL Model Height Offset" in the Geodetics Group under SETUP DATA.

Return to: top of page.

Return to: How-to Height - Tide and RTK