1. A method for optically imaging a dental structure within an oral cavity, comprising: providing a reference plate having position fiducials marked thereon; providing a position sensor coupled to the reference plate to read the fiducials and determine position; moving a support arm inside the oral cavity, the support arm coupled to the reference plate providing a fixed coordinate reference frame external to the oral cavity, the support arm further having a scanner probe positioned on an intra-oral end; moving one or more image apertures on the arm; determining the position of the one or more image apertures using the fixed coordinate reference frame; capturing one or more images of the dental structure through one or more of the image apertures; generating a 3D model of the dental structure based on the captured images; and following a path and orientation previously generated by a user during a pre-scan trace with the one or more image apertures along the dental structure surface to be imaged.