Chart Datum - Data type

Definition: Local vertical coordinate reference system which is used to refer and portray depth measurements as property values.

Description: NOTE This data type is intended to describe the main characteristics of a vertical CRS for measurement of depths in cases where this information is rarely or not available through a CRS registry (e.g. like EPSG).EXAMPLE Local datums for referring depths in lakes and navigable rivers.

INSPIRE Data Theme: Elevation - [INSPIRE Data Theme Elevation]

INSPIRE Application schema: Elevation - Vector Elements - [INSPIRE Application schema Elevation - Vector Elements]


Attributes

Definition: Water level determining the origin of depth measurements for the chart datum.

Description: EXAMPLE High water, low water, etc.NOTE 1 Values in the code list are applicable either for sea or inland waters.NOTE 2 When defining a depth datum for inland waters, it is recommended the use of "highWater", "lowWater" or "meanWaterLevel" - as applicable. All the other levels in the code list are well defined but usually just locally and do not serve for cross border purposes.

Multiplicity: 1

Valuetype: WaterLevelValue

Definition: Relative difference between the height of each reference point and the height of the water level determining the chart datum.

Description: NOTE 1 In order to calculate the offset parameter, the height(s) of the reference point(s) and the height of the water level determining the chart datum must be compared in the same vertical CRS.NOTE 2 When a single reference point is provided, the offset parameter is supposed to be zero (by default). If this condition is true, there is no need to inform the offset parameter.NOTE 3 When a set of reference points is provided, an individual offset parameter shall be provided for each of these points. The multiplicity between both properties - "referencePoint" and "offset" - is ordered with the aim to maintain this correspondence.

Multiplicity: 0...*

Valuetype: Measure

Definition: Geographical position(s) of:- Case A: a single point which is used to refer depth values within the geographical scope of the chart datum.- Case B: a set of points where water level measurements are performed to determine the water level of the chart datum.

Description: NOTE 1 The altimetric position of each reference point must be its height in a common vertical CRS: - in EVRS within its geographical scope (continental Europe).- in a vertical CRS identified and documented by the Member State concerned, outside the geographical scope of EVRS (overseas territories).NOTE 2 In Case A - The altimetric position of the reference point can be directly utilised as input to calculate approximate heights in a common vertical CRS for those vector objects whose depth values are referred to the chart datum. NOTE 3 In Case B - The altimetric positions of the reference points can be utilised, together with the respective offset parameter, as input to calculate approximate heights in a common vertical CRS for those vector objects whose depth values are referred to the water level of the chart datum. NOTE 4 The common vertical CRS mentioned in Note 2 and Note 3 shall be the one determined by Note 1.

Multiplicity: 1...*

Valuetype: GM_Point

Definition: Geographic scope in which the local depth datum is practically used.

Description: NOTE Chart datums should only be used to refer and portray depths at local level, since they are determined by a local water level. EXAMPLE 1 Lake or part of a lake in which a specific water level is used as depth datum.EXAMPLE 2 River section in which a specific water level is used as depth datum.EXAMPLE 3 Extent of the sea area in which a specific local tide level is used as depth datum.

Multiplicity: 1

Valuetype: EX_Extent



Back to top