EXPERIENCES OF LASER SCANNING FOR CLOSE RANGE STRUCTURAL 
RECORDING 
D. M. Barber 1 , J. P. Mills', P. G. Bryan 2 
1 School of Civil Engineering and Geosciences, University of Newcastle upon Tyne, Newcastle upon Tyne, NE1 7RU, UK - 
(d.m.barber, j.p.mills)@ncl.ac.uk 
English Heritage Metric Survey Team, 37 Tanner Row, York, YOl 6WP, UK-paul.bryan@english-heritage.org.uk 
KEY WORDS: Cultural-heritage, Laser scanning, Metric survey, Structural recording. 
ABSTRACT: 
Geomatics offers a wide range of solutions for close range measurement that can be applied to a disparate set of problems; however, 
survey workflows for projects are generally fixed to improve efficiency and standardise final deliverables. This paper will examine 
how one new survey technique, terrestrial laser scanning, may be introduced into a modern-day survey workflow. Terrestrial laser 
scanning is of great interest to surveyors, engineers, architects and archaeologists, and a wide range of scanning systems are now 
commercially available. The independent survey of two heritage sites within the UK has provided experience of laser scanning as a 
survey technique. Each survey utilised a different scanning system, namely the Riegl LMS Z210 to record a 14 th Century tower and 
the Cyrax 2500 to survey part of an 11 th Century priory. Both surveys also involved data derived from close range photogrammetry 
to allow a comparative assessment. Based on the experiences gained from these projects this paper highlights issues for 
consideration. It also comments on the complimentary use of different survey methods as an essential element for future survey 
practice. 
1. INTRODUCTION 
1.1. Motivation and methods for cultural-heritage 
recording 
Measured survey is an essential process in many projects that 
deal with buildings or structures. This is particularly true when 
dealing with historic buildings and monuments where survey 
data helps architects, engineers and building historians to 
understand the significance of a building and its surroundings. 
This understanding allows informed decisions on issues such as 
repair, conservation or redevelopment to be made. The use of 
metric survey techniques are especially necessary when high 
accuracy measurement is required, for example on sites where 
major alteration may occur or where features may be 
permanently lost (Clark, 2001). 
Understanding gained during the lifetime of a recording project 
is communicated through a system of reporting, archiving and 
publication; the contribution of the surveyor to this process is 
measured survey data in the form of floor plans, elevation 
drawings, sections, rectified photography, 3D CAD models and 
the periodic monitoring of surfaces or discrete points. The 
method used by surveyors to produce this information varies 
from project to project, but, in general, will involve at least one 
of three main techniques: hand recording, terrestrial survey or 
photogrammetry. Hand recording is performed by highly 
skilled professionals who produce annotated drawings and 
diagrams using tapes and grids. It is a specialist skill and 
normally applied to small, detailed areas or used to fill-in or 
augment survey data obtained by other techniques. The second 
available technique is terrestrial survey which includes the use 
of theodolite intersection, to record features and to provide 
control observations on which to base other techniques, in 
addition to the use of total stations for topographic site survey. 
It also includes, with the introduction of reflectorless EDM, the 
use of field portable CAD systems to simultaneously produce 
drawings and plans during measurement. The final technique at 
the surveyors disposal is image based measurement including 
photogrammetry and rectified photography. Image based 
methods are a long established tool for cultural-heritage 
recording. Imagery holds a great deal of information rapidly 
captured at a single point in time. Imagery, therefore, is a 
valuable source of archived data. Its application in this role can 
be seen after the fire at Windsor Castle in 1992 (Dallas et al., 
1995) and during the restoration of Castle Howard (Thompson, 
1962). 
1.2. Survey workflow 
When a public body such as English Heritage - the body 
responsible for conserving and enhancing the historic 
environment in England - commissions survey work it holds a 
responsibility to the tax-payer to demand good value and high 
quality. Practitioners are required to follow set specifications 
that provide objectives for the accuracy and quality of the final 
product. In order to meet these objectives the workflows used 
to implement survey techniques are well defined. 
The workflow to produce a photogrammetric line drawing 
involves a number of different stages. Typically, once a target 
network has been established and photography has been taken 
the remaining work is performed off-site. Film based 
photography requires photographic processing including the 
developing, printing and replication of diapositives followed by 
an inspection of the results. The control observations would 
then be used to calculate target positions, and again the results 
would be inspected and documented to ensure the work is 
meeting the set specification. At this stage, many survey 
projects simply require the raw data to be archived for 
measurement at a later date, if required; however, the 
production of a line drawing still requires further processing 
stages. The first of these will most likely be the scanning of the 
diapositives for use in a digital photogrammetric workstation 
(DPW). Once the stereomodel has been satisfactorily 
orientated (subject to tolerances set in the specification) 3D