Class: QgsGcpTransformerInterface

class qgis.analysis.QgsGcpTransformerInterface

Bases: sip.wrapper

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.

New in version 3.20.

QgsGcpTransformerInterface() Constructor for QgsGcpTransformerInterface

Enums

TransformMethod

Bases: enum.IntEnum

Methods

clone

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

create

Creates a new QgsGcpTransformerInterface subclass representing the specified transform method.

createFromParameters

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

method

Returns the transformation method.

methodToString

Returns a translated string representing the specified transform method.

minimumGcpCount

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

transform

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

updateParametersFromGcps

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

class TransformMethod(value)

Bases: enum.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
clone(self)QgsGcpTransformerInterface

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

QgsGcpTransformerInterface

create(method: QgsGcpTransformerInterface.TransformMethod)QgsGcpTransformerInterface

Creates a new QgsGcpTransformerInterface subclass representing the specified transform method.

Caller takes ownership of the returned object.

Parameters

method (QgsGcpTransformerInterface.TransformMethod) –

Return type

QgsGcpTransformerInterface

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

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
Return type

QgsGcpTransformerInterface

method(self)QgsGcpTransformerInterface.TransformMethod

Returns the transformation method.

Return type

QgsGcpTransformerInterface.TransformMethod

methodToString(method: QgsGcpTransformerInterface.TransformMethod)str

Returns a translated string representing the specified transform method.

Parameters

method (QgsGcpTransformerInterface.TransformMethod) –

Return type

str

minimumGcpCount(self)int

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)Tuple[bool, float, float]

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.

Return type

Tuple[bool, float, float]

Returns

True if transformation was successful.

Parameters
  • x (float) –

  • y (float) –

  • inverseTransform (bool = False) –

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

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) –