Abstract: Camera calibration is the process of determining the internal camera parameters and optical characteristics (intrinsic parameters). It also determines the relation between the two dimensional (2D) image and the corresponding three dimensional (3D) real points. Intrinsic camera parameters include: Focal Length, Principal Point, and Lens Distortion. In this paper, for estimating the intrinsic camera parameters, a simple and novel cost function is proposed based on the spatial geometry principles. Minimizing the proposed cost function, results in an accurate and simultaneous estimation of intrinsic camera parameters. Nonlinear Programming is used as the optimization method and the result shows the effectiveness of our proposed method.