  We give a non-iterative solution to a particular case of the four-point
three-views pose problem when three camera centers are collinear. Using the
well-known Cayley representation of orthogonal matrices, we derive from the
epipolar constraints a system of three polynomial equations in three variables.
The eliminant of that system is a multiple of a 36th degree univariate
polynomial. The true (unique) solution to the problem can be expressed in terms
of one of real roots of that polynomial. Experiments on synthetic data confirm
that our method is robust enough even in case of planar configurations.
