For each habitat map (GUI), a rectangular "Study Area" geographic bounding box should be created, encompassing the surveyed areas. The sides of the bounding box should be precisely horizontal and vertical when viewed unprojected in WGS84. In ArcGIS, this can be performed using the "Minimum bounding geometry" tool selecting "ENVELOPE" as the "Geometry Type", and grouping by the "GUI" field.
The resulting rectangular feature should look similar to Figure 1 (below).
Figure 1: An example habitat map (solid colours representing habitat types) and its respective Study Area polygon (red outline) viewed in unprojected WGS84.
The study area shapefile should contain only one feature and must be supplied in the Study Area Data Exchange Format (see step 3 and the Data Exchange Formats page).
The feature should be saved as a shapefile with the naming format of "[GUI]_StudyArea.shp". For example, the Study Area for habitat map GB012345 should be saved as "GB012345_StudyArea.shp"
When these outlines are combined by EMODnet Seabed Habitats, the layer can be used to display map extents and confidence scores.
Automating using Python
If you have ArcGIS and are comfortable with python, the creation of habitat map study areas can be automated by using the python script "studyarea_creator.py" available in our GitHub repository.
The script should be run on a folder containing only habitat maps that are formatted and named in accordance to steps 2 and 3.
The script will produce a correctly named shapefile in the Study Area DEF. The GUI value will be filled in automatically, but the confidence score for the map must be entered into the SUM_CONF field manually.