The inventive technique calculates lever arm values associated with a GNSS/INS system photogrammetrically. A calibrated camera on a device captures a plurality of images of the GNSS/INS system with the inclusion of a target, having known attributes and a plurality of control points. Thereafter, an application, executing on the device determines the lever arm values from the images of the GNSS/INS system utilizing the known attributes and the control points of the target. The INS may utilize the calculated lever arm values to combine information received from a GNSS receiver, of the GNSS/INS system, with information provided by sensors of the INS to compute updated positions, velocities, and/or orientations.