Multiple scan registration in LIDAR close-range applications

Terrestrial laser scanner technology is, today, one the most widely investigated topics in architectural applications. While the acquisition and filtering of the recorded points are well known procedures, the registration of adjacent scans is still a not completely investigated field. The registration of two adjacent scans with a large overlap can be properly solved either by using an interactive procedure (manual selection of homologous points) or automatically by using reflecting targets. Alternatively automatic registration can be performed by means of shape-reasoning procedure (e.g. spin images). Some practical problems arise when the object to be surveyed is large and one or two scans are not sufficient to geometrically describe it,. First of all the overlap between two adjacent scans must be reduced in order to speed up the acquisition phase; in a second step an “ad hoc” registration procedure must be conceived to avoid propagation errors. The paper shows the effect of the registration of multiple scans acquired in order to survey a large object and describes a procedure for the registration of multiple scans with minimum overlapping using the experience of photogrammetric triangulation adjustment.