Submitted to The 8th International Symposium on Virtual Reality, Archaeology and Cultural Heritage VAST (2007) Parametric Vector Modelling of Laser and Image Surveys of 17th Century Classical Architecture in Dublin

The product of a laser scan survey of a building or artefact is a point cloud which defines the geometry of the object, and when combined with image data the object edges and material textures can be identified. The point cloud survey is useful for visualisation and also as a record of the 3D surfaces of an object. Where conserva-tion or restoration work is to be carried out on the object conventional orthographic or 3D survey drawings are required. Survey drawings can be created by mapping vectors on to the point cloud or textured point cloud. This is a complex process as the data size of the point cloud is usually very large; also mapping in 3D space onto a point cloud is intricate due to difficulties in locating correct object planes and the detection of object edges. These problems have been overcome to a large extent using software platforms and plug inns which interface between CAD and point cloud processing software programmes. A method to improve auto-mation of vector mapping by plotting parametric vector objects on to the point cloud is examined in this pa-per. This study is based on a laser scan and image-based survey of 17th century classical architecture in Dub-lin. The parametric objects are created from the geometry of the point cloud correlated with the historic de-sign principles of classical architecture and then directly mapped on to the point cloud survey. The laser sur-vey can only record the surface of the object; construction details behind the surface can be detected from his-toric data, thus producing a full 3D and orthographic vector survey of an object or building. Categories and Subject Descriptors J.6 Computer-Aided Engineering, Computer-aided design (CAD) 1