A method for real time intra-orally acquiring and registering three-dimensional measurements and images of intra-oral objects and features, the intra-oral objects and features are located inside the oral cavity of a dental patient, optionally said intra-oral objects and features are selected from the group consisting of a part or entirety of a combination of teeth, gum, intra-oral soft tissue, bone matter, dental undercuts, and, dental fixtures and dental prostheses, permanent or removable, located inside the oral cavity of the dental patient, said method is comprising the steps of: (a) establishing an intra-oral fixed global registration position, inside the oral cavity of the dental patient in terms of global coordinate space of the oral cavity, said global coordinate space is associated with a fixed global reference coordinate system, which is a coordinate system that is fixed according to any stable object, said global coordinate space includes a plurality of intra-oral local coordinate spaces in the oral cavity; (b) providing a measuring and imaging device for measuring and imaging the intra-oral objects and features located in the oral cavity; (c) selecting a field of view of said measuring and imaging device located at a global position in said global coordinate space of the oral cavity; (d) acquiring at least one three-dimensional measurement and image of the intra-oral objects and features located in said selected field of view of said measuring and imaging device, and, recording said global position of said measuring and imaging device relative to said intra-oral fixed global registration position, for forming at least one globally recorded three-dimensional measurement and image of the intra-oral objects and features located in the oral cavity; (e) repeating step (c) and step (d) for a plurality of said global positions and a plurality of said fields of view of said measuring and imaging device, for forming a plurality of said globally recorded three-dimensional measurements and images of the intra-oral objects and features located in the oral cavity of the dental patient; and (f) registering local coordinate space pixel positions in each of said plurality of globally recorded three-dimensional measurements and images with corresponding global coordinate space pixel positions, for forming a plurality of the three-dimensional measurements and images of the intra-oral objects and features located in the oral cavity of the dental patient which are registered relative to same said intra-oral fixed global registration position. (a) establishing an intra-oral fixed global registration position, inside the oral cavity of the dental patient in terms of global coordinate space of the oral cavity, said global coordinate space is associated with a fixed global reference coordinate system, which is a coordinate system that is fixed according to any stable object, said global coordinate space includes a plurality of intra-oral local coordinate spaces in the oral cavity; (b) providing a measuring and imaging device for measuring and imaging the intra-oral objects and features located in the oral cavity; (c) selecting a field of view of said measuring and imaging device located at a global position in said global coordinate space of the oral cavity; (d) acquiring at least one three-dimensional measurement and image of the intra-oral objects and features located in said selected field of view of said measuring and imaging device, and, recording said global position of said measuring and imaging device relative to said intra-oral fixed global registration position, for forming at least one globally recorded three-dimensional measurement and image of the intra-oral objects and features located in the oral cavity; (e) repeating step (c) and step (d) for a plurality of said global positions and a plurality of said fields of view of said measuring and imaging device, for forming a plurality of said globally recorded three-dimensional measurements and images of the intra-oral objects and features located in the oral cavity of the dental patient; and (f) registering local coordinate space pixel positions in each of said plurality of globally recorded three-dimensional measurements and images with corresponding global coordinate space pixel positions, for forming a plurality of the three-dimensional measurements and images of the intra-oral objects and features located in the oral cavity of the dental patient which are registered relative to same said intra-oral fixed global registration position.