© ISO 2001 All rights reserved
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Table 9 – IG_Image Examples
Spatial\attribute properties
IG_SensorData IG_DerivedData CV_ReferenceableGrid
Ungeorectified images e.g. Landsat scene, digital aerial photo, NASA EOSDIS
Swath, SAR Ungeorectified derived data e.g. leaf
area index, soil moisture; usually intermediate products only until
rectified.
CV_RectifiedGrid Georectified Georectified images e.g.
orthoimages, image maps Georectified derived data e.g. gridded
leaf area index, soil moisture
8.3.1.2 Domain of IG_Image: CV_ReferenceableGrid and CV_RectifiedGrid
The spatial domain of IG_Image shall be an instance of one of two subclasses CV_Grid: CV_ReferenceableGrid and CV_RectifiedGrid SeeFigure 9. The difference between these two subclasses is the method in which the geolocation
information is used to determine the spatial coordinates of a CV_GridCell based on the cells grid coordinate.
A rectified grid shall be defined by an origin in an external coordinate reference system, and a set of offset vectors that specify the direction and distance between the grid lines. There is an affine transformation between the grid
coordinates and the external coordinate reference system, e.g, projected coordinate reference system.
An important type of image with a rectified grid is an orthoimage. An orthoimage is a rectified digital image in which displacement of objects in the image, due to sensor orientation and terrain relief, have been removed.
A referencable grid has information that can be used to transform grid coordinates to external coordinates, but the transformation shall not be required to be an affine transformation. Geolocation information for a Georeferenceable
Grid is defined in 19130. ISO 19130 describes techniques to geolocate georeferenceable imagery, e.g., sensor models, functional fit models, spatial registration using control points.
editors note: 19130 should change from Georeferenceable Dataset to Georeferenceable Grid as the georeferenceable modifier does not pertain to Sensor measurements, i.e., the values.
editors note: develop discussion of Geolocation quality: Spatial Resolution – GSD, Methods for reporting geolocation accuracy, affect of regridding on attribute values.
editors note: develop discussion on Spatial-Temporal Schema: Sensors moving in 4-D, New project in TC211
8.3.1.3 Range of IG_Image: IG_ImageValues
The attribute range of IG_Image shall be one of three subclasses of IG_ImageValues: IG_SensorDN, IG_SensorPhysicalData, or IG_DerivedData See Figure 10.
IG_SensorDN, a subtype of IG_ImageValues, shall contain the Digital Numbers DN produced by an image sensor. IG_SensorPhysicalData, a subtype of IG_ImageValues, shall contain values of the measurand of the sensor. For
example, for a optical radiation sensor, the IG_SensorPhysicalData are radiances at the sensor. IG_SensorPhysicalData is calculated from IG_SensorDN using IG_Sensor:Calibration determined by laboratory testing
or vicarious calibration.
IG_DerivedData, derived from IG_SensorData. is discussed in a later clause.
© ISO 2001 All rights reserved
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Figure 10 - IG_ImageValues
8.3.1.4 IG_PhysicalQuantity
