Classification of data and services

Topic category

• Oceans

Classification of data and services

Classification of data and services

Keywords

GEMET - INSPIRE themes, version 1.0 ( Theme )

• Sea regions

Geographic coverage

N

S

E

W

Temporal reference

Date ( Publication )

2021-10-18

Quality and validity

Lineage

The source DTMs used to calculate the land-sea limit are the following:

- LiDAR topo, bathy or mixed topo/bathy point clouds from the Litto3D® programme: these are point clouds produced by Shom or IGN as part of the Litto3D® programme from "pure" topographic, "pure" bathymetric or mixed topographic and bathymetric LiDAR flights.

"Pure" topographic LiDAR: the measurement density is at least 2 points/m2.

"Pure" bathymetric LiDAR: the measurement density, on land and at sea, is 3 to 4 points/25 m2 on average; this density increases regularly with the arrival of new sensors on the market.

Mixed LiDAR: the density of measurements at sea varies between 1 point/m2 (in the very shallow waters) and 1 point/25m2 (beyond). The density of measurements on land (intertidal area and land-sea limit area) is higher (4 points/m2).

These data have been cleaned of any "overground".

- Other LiDAR topo, bathy or mixed topo/bathy point clouds: these are point clouds produced by Shom or IGN outside the Litto3D® programme from LiDAR flights and according to specifications that are at least as demanding as the previous ones.

- Litto3D® DTM: it is the elevation model (1 m grid) generated by IGN and Shom resulting from the fusion of LiDAR topo and bathy acquisitions.

- RGE ALTI® DTM: it is the IGN high-resolution DTM reference (1 m grid), produced from topographic LiDAR acquisitions on the coast.

- Other DTMs: other "local" DTMs can be used (Shom photogrammetry, local GRID or TIN DTMs from drone surveys, etc.).

Beyond this list in order of preference, the most up-to-date data is preferred.

The HAT surface is compiled by Shom from two "inland extent" sources:

- either from the Bathyelli product, supplemented by recent data from Shom tide/current and harmonic constants databases, for France metropolitan area;

- or from another tidal model or other sources (Maritime Altimetric References, tide station record sheet), taking into account the latest in situ observations.

The type of boundary (artificial or natural) and the nature (sand, rock, etc.) are populated from other available data sources (OrtholittoraleV2, BDORTHO®, Shom oblique imagery, etc.); it is also a question of differentiating between high and low coasts, if necessary using a slope model derived from the coastal DTM.

In addition, the 3 administrative maritime limits contribute to the coherence of the land-sea limit in the rivers and lagoons.

Denominator

2000

Conformity