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.

Geodetic Configuration

For RTK tide, we still want to set up the Chart Datum, in case we would like to define a reference plane for the published heights.

Define your Horizontal (and vertical) Datum

Database Setup settings

Height Above Draft Reference

HADR is used to compute the actual water level, however it is not used to determine the height.

In other words, 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 set up a HADR and a Draft online.

In case of using a sub sea system it is good to think about having a real live draft input and a Depth sensor on your sub-surface object:

Define an underwater sensor system ('Draft' observation) on the surface object.
Define an underwater sensor system ('ROV Depth' observation) on the sub-surface object.

Positioning System

Define a Positioning System and the Receiver Positions/Heights in the Driver Setup.

Make sure to check what the reference datum is for the receiver data output. It is not always WGS84.

Define the exact location of the Positioning System relative to the CoG of the vessel.

Make sure to define all other systems relative to the CoG as well.

Computation Setup settings

Set the Height status of the positioning system in the Online - Settings - Computation Setup to "RTK (Accurate Height)".

Set the correct Priority for the heave sensors on the object (only in case of a redundant system).

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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.

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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)

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Generic Display Parameters

Parameter	Description
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
Heave	Heave 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. Note 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 Note 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. Note 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. Note 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 would 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 would 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).

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