hom_mat2d_reflectT_hom_mat2d_reflectHomMat2dReflectHomMat2dReflecthom_mat2d_reflect (Operator)

Name

hom_mat2d_reflectT_hom_mat2d_reflectHomMat2dReflectHomMat2dReflecthom_mat2d_reflect — Add a reflection to a homogeneous 2D transformation matrix.

Signature

Description

hom_mat2d_reflecthom_mat2d_reflectHomMat2dReflectHomMat2dReflectHomMat2dReflecthom_mat2d_reflect adds a reflection about the axis given by the two points (PxPxPxPxpxpx,PyPyPyPypypy) and (QxQxQxQxqxqx,QyQyQyQyqyqy) to the homogeneous 2D transformation matrix HomMat2DHomMat2DHomMat2DHomMat2DhomMat2Dhom_mat_2d and returns the resulting matrix in HomMat2DReflectHomMat2DReflectHomMat2DReflectHomMat2DReflecthomMat2DReflecthom_mat_2dreflect. The reflection is described by a 2×2 reflection matrix M. It is performed relative to the global (i.e., fixed) coordinate system; this corresponds to the following chain of transformation matrices:

The axis (PxPxPxPxpxpx,PyPyPyPypypy)-(QxQxQxQxqxqx,QyQyQyQyqyqy) is fixed in the transformation, i.e., the points on the axis remain unchanged when transformed using HomMat2DReflectHomMat2DReflectHomMat2DReflectHomMat2DReflecthomMat2DReflecthom_mat_2dreflect. To obtain this behavior, first a translation is added to the input transformation matrix that moves the axis onto the origin of the global coordinate system. Then, the reflection is added, and finally a translation that moves the axis back to its original position. This corresponds to the following chain of transformations:

To perform the transformation in the local coordinate system, i.e., the one described by HomMat2DHomMat2DHomMat2DHomMat2DhomMat2Dhom_mat_2d, use hom_mat2d_reflect_localhom_mat2d_reflect_localHomMat2dReflectLocalHomMat2dReflectLocalHomMat2dReflectLocalhom_mat2d_reflect_local.

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 (RowRowRowRowrowrow,ColumnColumnColumnColumncolumncolumn). 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.

Note that homogeneous matrices are stored row-by-row as a tuple; the last row is usually not stored because it is identical for all homogeneous matrices that describe an affine transformation. For example, the homogeneous matrix is stored as the tuple [ra, rb, tc, rd, re, tf]. However, it is also possible to process full 3×3 matrices, which represent a projective 2D 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

Result

hom_mat2d_reflecthom_mat2d_reflectHomMat2dReflectHomMat2dReflectHomMat2dReflecthom_mat2d_reflect returns TRUE if both points on the axis are not identical. If necessary, an exception is raised.

Possible Predecessors

hom_mat2d_identityhom_mat2d_identityHomMat2dIdentityHomMat2dIdentityHomMat2dIdentityhom_mat2d_identity, hom_mat2d_translatehom_mat2d_translateHomMat2dTranslateHomMat2dTranslateHomMat2dTranslatehom_mat2d_translate, hom_mat2d_scalehom_mat2d_scaleHomMat2dScaleHomMat2dScaleHomMat2dScalehom_mat2d_scale, hom_mat2d_rotatehom_mat2d_rotateHomMat2dRotateHomMat2dRotateHomMat2dRotatehom_mat2d_rotate, hom_mat2d_slanthom_mat2d_slantHomMat2dSlantHomMat2dSlantHomMat2dSlanthom_mat2d_slant, hom_mat2d_reflecthom_mat2d_reflectHomMat2dReflectHomMat2dReflectHomMat2dReflecthom_mat2d_reflect

Possible Successors

hom_mat2d_translatehom_mat2d_translateHomMat2dTranslateHomMat2dTranslateHomMat2dTranslatehom_mat2d_translate, hom_mat2d_scalehom_mat2d_scaleHomMat2dScaleHomMat2dScaleHomMat2dScalehom_mat2d_scale, hom_mat2d_rotatehom_mat2d_rotateHomMat2dRotateHomMat2dRotateHomMat2dRotatehom_mat2d_rotate, hom_mat2d_slanthom_mat2d_slantHomMat2dSlantHomMat2dSlantHomMat2dSlanthom_mat2d_slant, hom_mat2d_reflecthom_mat2d_reflectHomMat2dReflectHomMat2dReflectHomMat2dReflecthom_mat2d_reflect

See also

hom_mat2d_reflect_localhom_mat2d_reflect_localHomMat2dReflectLocalHomMat2dReflectLocalHomMat2dReflectLocalhom_mat2d_reflect_local

Module

Foundation