
Linear and Affine Algebra 327
Thus, it is simple enough to compose matrices as a product. The more difficult
problem is how to decompose a matrix into translations, rotations, scalings,
and shearings. That is the topic of the next section.
A special set of transformations is the set of rigid transformations.These
consist of products of translations and rotations. An object for which all its
points are transformed by translations and rotations retains its shape—only
its location and orientation vary. A rigid transformation is of the form
H =
R
T
0
T
1
(6.134)
Another special set of transformations involve only translations, uniform
scalings, and rotations. I