Operator Reference

HALCON Operator Reference / Transformations / 2D Transformations

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vector_to_rigidT_vector_to_rigidVectorToRigidVectorToRigidvector_to_rigid (Operator)

vector_to_rigidT_vector_to_rigidVectorToRigidVectorToRigidvector_to_rigid — Approximate a rigid affine transformation from point correspondences.

Signature

vector_to_rigid( : : Px, Py, Qx, Qy : HomMat2D)

Herror T_vector_to_rigid(const Htuple Px, const Htuple Py, const Htuple Qx, const Htuple Qy, Htuple* HomMat2D)

void VectorToRigid(const HTuple& Px, const HTuple& Py, const HTuple& Qx, const HTuple& Qy, HTuple* HomMat2D)

void HHomMat2D::VectorToRigid(const HTuple& Px, const HTuple& Py, const HTuple& Qx, const HTuple& Qy)

static void HOperatorSet.VectorToRigid(HTuple px, HTuple py, HTuple qx, HTuple qy, out HTuple homMat2D)

void HHomMat2D.VectorToRigid(HTuple px, HTuple py, HTuple qx, HTuple qy)

def vector_to_rigid(px: Sequence[float], py: Sequence[float], qx: Sequence[float], qy: Sequence[float]) -> Sequence[float]

Description

vector_to_rigidvector_to_rigidVectorToRigidVectorToRigidvector_to_rigid approximates a rigid affine transformation, i.e., a transformation consisting of a rotation and a translation, from at least two point correspondences and returns it as the homogeneous transformation matrix HomMat2DHomMat2DHomMat2DhomMat2Dhom_mat_2d. The matrix consists of 2 components: a rotation matrix R and a translation vector t (also see hom_mat2d_rotatehom_mat2d_rotateHomMat2dRotateHomMat2dRotatehom_mat2d_rotate and hom_mat2d_translatehom_mat2d_translateHomMat2dTranslateHomMat2dTranslatehom_mat2d_translate):

The point correspondences are passed in the tuples (PxPxPxpxpx, PyPyPypypy) and (QxQxQxqxqx,QyQyQyqyqy), where corresponding points must be at the same index positions in the tuples. The transformation is always overdetermined. Therefore, the returned transformation is the transformation that minimizes the distances between the original points (PxPxPxpxpx,PyPyPypypy) and the transformed points (QxQxQxqxqx,QyQyQyqyqy), as described in the following equation (points as homogeneous vectors):

HomMat2DHomMat2DHomMat2DhomMat2Dhom_mat_2d can be used directly with operators that transform data using affine transformations, e.g., affine_trans_imageaffine_trans_imageAffineTransImageAffineTransImageaffine_trans_image.

Attention

It should be noted that homogeneous transformation matrices refer to a general right-handed mathematical coordinate system. If a homogeneous transformation matrix is used to transform images, regions, XLD contours, or any other data that has been extracted from images, the row coordinates of the transformation must be passed in the x coordinates, while the column coordinates must be passed in the y coordinates. Consequently, the order of passing row and column coordinates follows the usual order (RowRowRowrowrow,ColumnColumnColumncolumncolumn). This convention is essential to obtain a right-handed coordinate system for the transformation of iconic data, and consequently to ensure in particular that rotations are performed in the correct mathematical direction.

Furthermore, it should be noted that if a homogeneous transformation matrix is used to transform images, regions, XLD contours, or any other data that has been extracted from images, it is assumed that the origin of the coordinate system of the homogeneous transformation matrix lies in the upper left corner of a pixel. The image processing operators that return point coordinates, however, assume a coordinate system in which the origin lies in the center of a pixel. Therefore, to obtain a consistent homogeneous transformation matrix, 0.5 must be added to the point coordinates before computing the transformation.

Execution Information

• Multithreading type: reentrant (runs in parallel with non-exclusive operators).
• Multithreading scope: global (may be called from any thread).
• Processed without parallelization.

Parameters

PxPxPxpxpx (input_control)  point.x-array → HTupleSequence[float]HTupleHtuple (real) (double) (double) (double)

X coordinates of the original points.

PyPyPypypy (input_control)  point.y-array → HTupleSequence[float]HTupleHtuple (real) (double) (double) (double)

Y coordinates of the original points.

QxQxQxqxqx (input_control)  point.x-array → HTupleSequence[float]HTupleHtuple (real) (double) (double) (double)

X coordinates of the transformed points.

QyQyQyqyqy (input_control)  point.y-array → HTupleSequence[float]HTupleHtuple (real) (double) (double) (double)

Y coordinates of the transformed points.

HomMat2DHomMat2DHomMat2DhomMat2Dhom_mat_2d (output_control)  hom_mat2d → HHomMat2D, HTupleSequence[float]HTupleHtuple (real) (double) (double) (double)

Output transformation matrix.

Possible Successors

affine_trans_imageaffine_trans_imageAffineTransImageAffineTransImageaffine_trans_image, affine_trans_image_sizeaffine_trans_image_sizeAffineTransImageSizeAffineTransImageSizeaffine_trans_image_size, affine_trans_regionaffine_trans_regionAffineTransRegionAffineTransRegionaffine_trans_region, affine_trans_contour_xldaffine_trans_contour_xldAffineTransContourXldAffineTransContourXldaffine_trans_contour_xld, affine_trans_polygon_xldaffine_trans_polygon_xldAffineTransPolygonXldAffineTransPolygonXldaffine_trans_polygon_xld, affine_trans_point_2daffine_trans_point_2dAffineTransPoint2dAffineTransPoint2daffine_trans_point_2d

Alternatives

vector_to_hom_mat2dvector_to_hom_mat2dVectorToHomMat2dVectorToHomMat2dvector_to_hom_mat2d, vector_to_anisovector_to_anisoVectorToAnisoVectorToAnisovector_to_aniso, vector_to_similarityvector_to_similarityVectorToSimilarityVectorToSimilarityvector_to_similarity

See also

vector_field_to_hom_mat2dvector_field_to_hom_mat2dVectorFieldToHomMat2dVectorFieldToHomMat2dvector_field_to_hom_mat2d, point_line_to_hom_mat2dpoint_line_to_hom_mat2dPointLineToHomMat2dPointLineToHomMat2dpoint_line_to_hom_mat2d

Module

Foundation

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