Class: QgsGcpTransformerInterface¶

An interface for Ground Control Points (GCP) based transformations.

QgsGcpTransformerInterface implementations are able to transform point locations based on a transformation method and a list of GCPs.

Added in version 3.20.

Note

This is an abstract class, with methods which must be implemented by a subclass.

The following methods must be implemented: clone(), method(), minimumGcpCount(), updateParametersFromGcps()

class qgis.analysis.QgsGcpTransformerInterface[source]¶

Bases: object

class TransformMethod(*values)¶

Bases: IntEnum

Available transformation methods.

Linear: Linear transform
Helmert: Helmert transform
PolynomialOrder1: Polynomial order 1
PolynomialOrder2: Polyonmial order 2
PolynomialOrder3: Polynomial order
ThinPlateSpline: Thin plate splines
Projective: Projective
InvalidTransform: Invalid transform

Helmert = 1¶

InvalidTransform = 65535¶

Linear = 0¶

PolynomialOrder1 = 2¶

PolynomialOrder2 = 3¶

PolynomialOrder3 = 4¶

Projective = 6¶

ThinPlateSpline = 5¶

abstract clone(self) → QgsGcpTransformerInterface | None[source]¶

Clones the transformer, returning a new copy of the transformer with the same parameters as this one.

Caller takes ownership of the returned object.

Return type:: Optional[QgsGcpTransformerInterface]

static create(method: QgsGcpTransformerInterface.TransformMethod) → QgsGcpTransformerInterface | None[source]¶

Creates a new QgsGcpTransformerInterface subclass representing the specified transform method.

Caller takes ownership of the returned object.

Parameters:: method (QgsGcpTransformerInterface.TransformMethod)
Return type:: Optional[QgsGcpTransformerInterface]

static createFromParameters(method: QgsGcpTransformerInterface.TransformMethod, sourceCoordinates: Iterable[QgsPointXY], destinationCoordinates: Iterable[QgsPointXY]) → QgsGcpTransformerInterface | None[source]¶

Creates a new QgsGcpTransformerInterface subclass representing the specified transform method, initialized using the given lists of source and destination coordinates.

If the parameters cannot be fit to a transform None will be returned.

Caller takes ownership of the returned object.

Parameters:

method (QgsGcpTransformerInterface.TransformMethod)
sourceCoordinates (Iterable[QgsPointXY])
destinationCoordinates (Iterable[QgsPointXY])

Return type:

Optional[QgsGcpTransformerInterface]

abstract method(self) → QgsGcpTransformerInterface.TransformMethod[source]¶

Returns the transformation method.

Return type:: QgsGcpTransformerInterface.TransformMethod

static methodToString(method: QgsGcpTransformerInterface.TransformMethod) → str[source]¶

Returns a translated string representing the specified transform method.

Parameters:: method (QgsGcpTransformerInterface.TransformMethod)
Return type:: str

abstract minimumGcpCount(self) → int[source]¶

Returns the minimum number of Ground Control Points (GCPs) required for parameter fitting.

Return type:: int

transform(self, x: float, y: float, inverseTransform: bool = False)[source]¶

Transforms the point (x, y) from source to destination coordinates.

If inverseTransform is set to True, the point will be transformed from the destination to the source.

Returns:

True if transformation was successful.

Parameters:

x (float)
y (float)
inverseTransform (bool = False) -> (bool)

abstract updateParametersFromGcps(self, sourceCoordinates: Iterable[QgsPointXY], destinationCoordinates: Iterable[QgsPointXY], invertYAxis: bool = False) → bool[source]¶

Fits transformation parameters using the specified Ground Control Points (GCPs) lists of source and destination coordinates.

If invertYAxis is set to True then the y-axis of source coordinates will be inverted, e.g. to allow for transformation of raster layers with ascending top-to-bottom vertical axis coordinates.

Return type:

bool

Returns:

True on success, False on failure

Parameters:

sourceCoordinates (Iterable[QgsPointXY])
destinationCoordinates (Iterable[QgsPointXY])
invertYAxis (bool = False)