3d scanning is a reverse engineering process where 3d scanners are used to collect the shape and appearance data of a physical object to recreate the digital model of the same either to reproduce or modify.
3d scanning can be used in many different applications like creating assets for games, movies etc but speaking specifically about engineering and 3d printing domain it is mostly used for reverse engineering where measuring the exact dimensions of a product is difficult or if the product is organic shapes and difficult to recreate. Apart for engineering applications 3d scanning can also be used to generate artistic 3d model of a person, object etc
We use multiple technologies for 3D Scanning. Each of the technology
comes with its advantages and limitations. Common applications of this
technology include augmented reality, motion capture, industrial design,
prosthetics, reverse engineering and prototyping, quality control/inspection,
Medical, Construction, etc