Trifocal Tensor - Correlation Slices

The tensor can also be seen as a collection of three rank-two 3 x 3 matrices known as its correlation slices. Assuming that the projection matrices of three views are, and, the correlation slices of the corresponding tensor can be expressed in closed form as, where are respectively the ith columns of the camera matrices. In practice, however, the tensor is estimated from point and line matches across the three views.