In this paper we present the enhancement of an existing closed-form solution for metric velocity determination utilizing monocular images in combination with accelerometer and gyroscope measurements. While the original version of this algorithm depends on external attitude information for gravity compensation, our solution allows for gravity compensation through the addition of magnetometer measurements. The proposed algorithm results in a linear system of equations which is solvable for accelerated trajectories of an agent carrying the aforementioned sensors. If this condition is met the solution directly provides scaled metric information about the velocity, the distance to landmarks and the direction of gravity in the agent's frame. The authors propose consideration of this algorithm for the initialization of monocular vision navigation filters.