The estimation of a camera’s pose is possible when at least four correspondences exist. The 3D positions of the features have to be known. Two general approaches exist, algebraic and optimising ones. Algebraic methods construct an overdetermined system of equations out of the correspon- dences and solve it. They include the linear 4-point algorithm[QL99], factorisation methods and bundle adjustment. In general, they are fast, but very sensitive to noise and numerically instable.