-- Name -- breakline -- Definition -- A line of a critical nature which describes the shape of an elevation surface and indicates a discontinuity in the slope of the surface (i.e. an abrupt change in gradient). Triangles included within a TIN model must never cross it. -- Description -- SOURCE Adapted from [ISO 19107:2003]. EXAMPLE Breaklines represent local ridges or depressions (streams or drainage lines) in the surface, man-made structures (e.g. roads), etc. NOTE 1 A breakline connects points with different elevation and therefore its description using 2.5-D coordinates (using the 'geometry' attribute) is fully recommended. NOTE 2 No triangle in a TIN may cross a breakline (in other words, breakline segments are enforced as triangle edges), even if doing so violates the triangulation criterion. NOTE 3 All breaklines are located on the ground surface or on any of the artificial structures built on it. NOTE 4 Breaklines are useful as input data for the generation of a more appropriate or accurate digital elevation model by using interpolation methods.
-- Name -- isolated area -- Definition -- Delimitation of an area of the Earth's surface where an isolated part of the elevation model exists. Its outside surroundings have no elevation information. -- Description -- SOURCE Adapted from "IslandArea" [GIS4EU D3.5]. NOTE 1 It includes the delimitation of any island of elevation data which are isolated from the main DEM. They may be included inside void areas. NOTE 2 Isolated areas can be useful as masks when calculating a more appropriate or accurate DEM.
-- Name -- spot elevation -- Definition -- Point spatial object which describes the elevation of an Earth's surface at a specific location. It provides a single elevation property value. -- Description -- NOTE 1 It often represents a singular point in the morphology of a land or water body's floor surface. NOTE 2 The attribute propertyType is equal to 'height' in the case of spot heights. It is equal to 'depth' in the case of spot depths.
-- Name -- void area -- Definition -- Area of the Earth's surface where the elevation model is unknown because of missing input data. This area shall be excluded from a DEM. -- Description -- SOURCE "ObscureArea" [GIS4EU D3.5]. NOTE 1 A void area may contain a number of isolated areas with elevation data. These are considered as holes of the container void area. NOTE 2 Void areas can be useful as masks when calculating a more appropriate or accurate DEM.
-- Name -- contour line -- Definition -- Linear spatial object composed of a set of adjoining locations characterized by having the same elevation property value. It describes, together with other contour lines present in the area, the local morphology of the Earth's surface. -- Description -- NOTE 1 The attribute propertyType is equal to 'height' in the case of contour lines and it is equal to 'depth' in the case of depth contours.
-- Name -- elevation vector object -- Definition -- Elevation spatial object forming part of a vector data set, which participates in the description of the elevation property of a real world surface. It consists of an identity base for all vector objects which can be included as part of an elevation data set. -- Description -- It is an abstract feature type which generically describes every possible type of elevation vector object. It includes common attributes, properties and constraints for such spatial objects.
-- Name -- chart datum -- 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.
-- Name -- breakline type value -- Definition -- List of possible type values for break lines based on the physical characteristics of the break line [in the elevation surface].
-- Name -- spot elevation classification value -- Definition -- Possible classification values for spot elevations based on the LAS specification maintained by the American Society for Photogrammetry and Remote Sensing (ASPRS). -- Description -- NOTE These classes are proposed regardless of the adquisition method of the spot elevation. They correspond to the ASPRS Standard LIDAR Point Classes.
-- Name -- spot elevation type value -- Definition -- Possible values for spot elevation points that describe a singularity of the surface.
-- Name -- contour line type value -- Definition -- List of possible categories of contour lines based on the equidistance parameter of the data set.