Abstract. In this theoretical paper we consider the problem of accurately triangulating a scene plane. Rather than first triangulating a set of points and then fitting a plane to these points, we try to minimize the back-projection errors as functions of the plane parameters directly. As this is both geometrically and statistically meaningful our method performs better than the standard two step procedure. Furthermore, we show that the error residuals of this formulation are quasiconvex thereby making it very easy to solve using for example standard local optimization methods.