A system uses range and Doppler velocity measurements from a lidar subsystem and images from a video subsystem to estimate a six degree-of-freedom trajectory of a target. The video subsystem and the lidar subsystem may be aligned with one another, and hence calibrated, by determining, for example, a centroid of an iris determined from the lidar subsystem and a centroid of the iris determined from the video subsystem and determining a calibration offset between the two centroids.