hom_mat2d_translate — Add a translation to a homogeneous 2D transformation matrix.
hom_mat2d_translate( : : HomMat2D, Tx, Ty : HomMat2DTranslate)
hom_mat2d_translate adds a translation by the vector
t = (Tx,Ty) to the
homogeneous 2D transformation matrix HomMat2D and returns the
resulting matrix in HomMat2DTranslate. The translation is performed
relative to the global (i.e., fixed) coordinate system; this corresponds to
the following chain of transformation matrices:
To perform the transformation in the local coordinate system, i.e.,
the one described by HomMat2D, use
hom_mat2d_translate_local.
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
(Row,Column). 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.
HomMat2D (input_control) hom_mat2d → (real)
Input transformation matrix.
Tx (input_control) point.x → (real / integer)
Translation along the x-axis.
Default value: 64
Suggested values: 0, 16, 32, 64, 128, 256, 512, 1024
Ty (input_control) point.y → (real / integer)
Translation along the y-axis.
Default value: 64
Suggested values: 0, 16, 32, 64, 128, 256, 512, 1024
HomMat2DTranslate (output_control) hom_mat2d → (real)
Output transformation matrix.
If the parameters are valid, the operator hom_mat2d_translate returns
2 (H_MSG_TRUE). If necessary, an exception is raised.
hom_mat2d_identity,
hom_mat2d_translate,
hom_mat2d_scale,
hom_mat2d_rotate,
hom_mat2d_slant,
hom_mat2d_reflect
hom_mat2d_translate,
hom_mat2d_scale,
hom_mat2d_rotate,
hom_mat2d_slant,
hom_mat2d_reflect
Foundation