Data Specification on Orthoimagery – Draft ... - INSPIRE - Europa

INSPIRE Reference: D2.8.II.3_v2.0
TWG-OI <strong>Data</strong> <strong>Specification</strong> on Orthoimagery 2011-06-15 Page 12
properties necessary to process the coverage: domainSet and rangeType describe the structures of
respectively the domain (i.e. geometry) and the range values of the coverage. RangeSet contains the
feature attributes values whereas coverageFunction explains how to assign the records to the points
of the grid. For a more detailed description of these inherited attributes, see the section 9.9.4 of the
GCM [DS-D2.5]. The domainExtent and interpolationType attributes stemming from ISO 19123
complete the description of the coverage characteristics.
IR Requirement 3 The domainExtent attribute of every OrthoimageCoverage instance shall be at
least populated with a subtype of the EX_GeographicExtent type.
NOTE The EX_GeographicExtent abstract class is specialized by the EX_BoundingPolygon,
EX_GeographicBoundingBox and EX_GeographicDescription classes specified in ISO 19115.
Other attributes provide additional information about identification (inspireId, name), temporal aspects
(phenomenonTime, beginLifespanVersion,endLifespanVersion) and refined extent (footprint). The
property footprint of type GM_MultiSurface precisely delineates the geographic areas where the
coverage range is of interest (e.g. no nil values).
Figure 6 – footprint and bounding box of an orthoimage (respectively in blue and red)
IR Requirement 4 The footprint of an OrthoimageCoverage instance shall be spatially included in its
geographic extent.
NOTE The inclusion is not necessary strict, i.e. the footprint may be equal to the geographic extent.
The inheritance from RectifiedGridCoverage implies that the domain of an orthoimage coverage is
modelled as a CV_RectifiedGrid. This ISO 19123 element carries among other things the
georeference of the orthoimage that consists of the coordinates of a given corner expressed in an
external coordinate reference system (CV_RectifiedGrid::origin), the resolution or ground sample
distance (CV_RectifiedGrid::offsetVectors) and the image width and length expressed in pixels
(CV_RectifiedGrid::extent).
5.2.1.2.2. OrthoimageCoverage aggregation
As stated in 5.2.1.1.4, an OrthoimageCoverage instance can be an aggregation of other
OrthoimageCoverage instances. However certain conditions are required:
IR Requirement 5 All the OrthoimageCoverage instances referred to by a same aggregated
OrthoimageCoverage instance shall be consistent. That is, they shall share the
same range type, Coordinate Reference System and resolution. They shall also
support cell alignment.
The data structure is implemented by the recursive UML aggregation linking the OrthoimageCoverage
class to itself. The OrthoimageAggregation association class indicates through the
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