A three-dimensional (3D) measuring system that includes an external projector and an imager device. The imager device having a projector, a first camera and a second camera. The system further having one or more processors operably coupled to the display, the projector, the first camera and the second camera. The processors are responsive to executable computer instructions when executed on the one or more processors for projecting one or more random patterns on an object, recording one or more stereo images of the object, estimating a position and orientation of an imager device and registering scan data generated from the estimated position and orientation of the imager device into a coordinate system.