Proceedings 18 th International Symposium CIPA 2001 
Potsdam (Germany), September 18 - 21, 2001 
LASER SCANNING AND PHOTOGRAMMETRY: 21 st CENTURY METROLOGY 
David Barber, Dr. Jon Mills 
Department of Geomatics 
University of Newcastle upon Tyne 
Newcastle upon Tyne, UK 
E-mail: d.m.barber@ncl.ac.uk, j.p.mills@ncl.ac.uk 
Paul G. Bryan 
UK Representative for CIPA 
English Heritage Metric Survey Team 
Tanner Row 
York, UK 
E-mail: paul.bryan@english-heritage.org.uk 
KEY WORDS: Laser Scanning, Photogrammetry, Integration 
ABSTRACT 
New technologies often turn heads the first time they appear. Laser scanning is one such new technique, which has impressed many 
users by the ability of point clouds to provide an understanding of complex subjects. Laser scanning holds obvious benefits to 
architectural recording, however such technology should not be used with blind faith as a solution to all problems. As with all new 
technological developments, the dissemination of information is a vital part of laser scanning’s acceptance into everyday practice. 
This paper outlines the considerations involved in the application of laser scanning to architectural projects. By examining different 
scanning systems, issues such as resolution, reflectance and data presentation are discussed. It also emphasizes the now familiar call 
towards the seamless integration of laser scanning with other methodologies. The development of an integrated system, based on the 
21 st century technology of laser scanning and the 19 th century science of photogrammetry, is seen as a valuable step in the acceptance 
of laser scanning as a methodology to record and model millennium old infrastructure. 
1. INTRODUCTION 
For in excess of a century, architectural photogrammetry has played an important role in the documentation of historic buildings and 
monuments. Waldhausl (1992) discusses the unchanged demand for architectural photogrammetry, but states that photogrammetry 
has not achieved success in the rapid documentation of architectural heritage. Maturity into third generation Digital Photogrammetric 
Systems has improved the capacity of photogrammetry to meet the needs of the heritage community with common deliverables now 
including orthophotographs and digital surface models in addition to traditional line drawings. Techniques such as digitally rectified 
photography have simplified documentation and are fast becoming flexible and accessible survey tools (Bryan et al., 1999). 
Reflectorless EDM measurement is also widely used to create basic frameworks connecting different survey methodologies and is a 
valuable aid in the fixing of inaccessible detail (Blake, 1998). 
Over the past few years terrestrial laser scanning has emerged with the potential to be of major value to the architectural recording 
professional. The available scanning systems extend to all object types, almost regardless of scale and complexity, thus allowing the 
contribution of laser scanning in future documentation projects. Scanners may be categorized into two groups: scanners where the 
scanner to object distance is typically less than 2m, which generally operate on the principle of triangulation, and scanners where the 
scanner to object distance is typically above 2m, these scanners normally work on a of time of flight principle. 2 
2. CURRENT STATE OF LASER SCANNING 
2.1 Triangulation Scanners 
Triangulation scanners consist of a laser and at least one charge coupled device (CCD) housed in a single unit, the “scanner head”. 
The CCD is used to record the displacement of a stripe of laser light projected onto an object, Figure 1. The geometry between the 
laser and CCD is known and allows triangulation to be used to determine a point measurement. A full XYZ position can be 
calculated if the location and orientation of the scanner is known (Fowles, 2000). For some scanners this location may be fixed but 
other systems use a mechanical arm to record the position of the scanner head, the operator then guides the stripe over the surface of 
the object. (These arms may be used in their own right as coordinate measurement machines). A second method for the fixing of the 
scanner head is the use of magnetic trackers enabling movement without physical restrictions, within the range of the tracking 
system.