New terms introduced in the Georeference Extension

georeferencing

Georeference Annotations use georeferencing as the value for their motivation. The motivation property is part of the Web Annotation specification.

resourceCoords

The resourceCoords property appears inside each properties object of each Ground Control Point (GCP). It defines the resource coordinates of the GCP.

transformation

The transformation property may appear in the body of a Georeference Annotation to supply clients with information about the preferred transformation algorithm. Its value is a JSON object with properties type and options.

type

The preferred transformation algorithm that clients should use for the GCPs in a specific Georeference Annotation. It appears as the type property of a transformation object and does not override the meaning of any other type property. Valid values are thinPlateSpline and polynomial.

options

A property that appears within a transformation object to supply additional parameters related to the selected transformation type.

order

A property that appears within a transformation object with a polynomial transformation type. The value will be 1 for first order linear transformations, 2 for second order quadratic transformation, or 3 for third order cubic transformations.

thinPlateSpline

thinPlateSpline is one of the possible values of the transformation type property. It means that ‘thin plate spline’ transformation algorithm should be used. Thin plate spline is also known as rubbersheeting.

polynomial

polynomial is one of the possible values of the transformation type property. It indicates that a first, second or third order polynomial transformation should be used.