Scan to BIM is a workflow which should start with survey-grade, as-built 3D laser scan survey data (collected using a 3D terrestrial or mobile high definition laser scanner) ensuring all details of a building structure (internal or external) are scanned and registered.
From the resultant “point cloud” relevant data can then be derived using 2D CAD drafting and 3D modelling techniques to provide, in most cases, a 3D Building Information Model (BIM).