The multiple view geometry in space-time can represent multiple view geometry in the case where nonrigid arbitrary motions are viewed from multiple translational cameras. However, it requires many corresponding points and is sensitive to the image noise. In this paper, we investigate mutual projections of cameras in four-dimensional space, and show it enables us to reduce the number of corresponding points required for computing the multiple view geometry in spacetime. Surprisingly, we no longer need any corresponding points for computing the multiple view geometry in space-time, if all the cameras are projected to the other cameras mutually for two time intervals. We also show that the stability of the computation of multiple view geometry in space-time is drastically improved by considering the mutual projections of cameras.