A Practical Approach to Camera Calibration for Part Alignment for Hybrid Additive Manufacturing Using Computer Vision

Additive manufacturing (AM) is a process that involves building up thin layers of material, one by one creating a three-dimensional object from a digital file. The technology can produce complex shapes that are not possible with traditional casting and machining methods, or subtractive techniques. Hybrid AM is the process in which the AM process takes place on an existing part in the AM chamber. The existing part could have been manufactured by the traditional subtractive manufacturing process. The powder bed fusion process includes the following commonly used printing techniques such as direct metal laser sintering, electron beam melting, selective heat sintering, selective laser melting (SLM) and selective laser sintering (SLS). Laser sintering requires a scan path by which the laser travels and welds the metal powder to form layers over layers. Computer vision can help to locate the part on which the laser has to be fired. Camera calibration is one of the techniques in computer vision by which the world (object) 3D coordinates are converted into 2D image coordinates. Practically, it becomes essential to know the exact position of the camera, i.e., camera intrinsic. Camera calibration technique provides camera intrinsic and gives out extrinsic, i.e., 2D coordinates.