3D Laser Scanning for Heritage Advice and Guidance on the Use of Laser Scanning in Archaeology and Architecture Summary
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3D Laser Scanning for Heritage Advice and Guidance on the Use of Laser Scanning in Archaeology and Architecture Summary The first edition of 3D Laser Scanning for Heritage was published in 2007 and originated from the Heritage3D project that in 2006 considered the development of professional guidance for laser scanning in archaeology and architecture. Publication of the second edition in 2011 continued the aims of the original document in providing updated guidance on the use of three-dimensional (3D) laser scanning across the heritage sector. By reflecting on the technological advances made since 2011, such as the speed, resolution, mobility and portability of modern laser scanning systems and their integration with other sensor solutions, the guidance presented in this third edition should assist archaeologists, conservators and other cultural heritage professionals unfamiliar with the approach in making the best possible use of this now highly developed technique. This document has been prepared by Clive Boardman MA MSc FCInstCES FRSPSoc of Imetria Ltd/University of York and Paul Bryan BSc FRICS.This edition published by Historic England, January 2018. All images in the main text © Historic England unless otherwise stated. Please refer to this document as: Historic England 2018 3D Laser Scanning for Heritage: Advice and Guidance on the Use of Laser Scanning in Archaeology and Architecture. Swindon. Historic England. HistoricEngland.org.uk/advice/technical-advice/recording-heritage/ Front cover: The Iron Bridge is Britain’s best known industrial monument and is situated in Ironbridge Gorge on the River Severn in Shropshire. Built between 1779 and 1781, it is 30m high and the first in the world to use cast iron construction on an industrial scale. In 2012 a laser scan survey of the bridge and immediate surroundings was carried out which would act as both an archive of the structure and as the basis for the creation of a detailed three-dimensional (3D) model for analysis as part of the bridge conservation plan. It is now a major conservation project for English Heritage that will see the different elements of the bridge undergo detailed examination, conservation and repairs to the cracking caused by ground movements. Front cover: The Iron Bridge A laser scan survey of The Iron Bridge was undertaken in 2012 that has contributed to the current investigation, repair and conservation of this iconic industrial monument © APR Services Contents Introduction .........................................1 3 Specifying and Commissioning a Survey ....................................44 Document outline and objectives ..........................1 3.1 The purpose of the survey ........................44 Metric survey ............................................................1 3.2 In-house or contractor survey ..................45 3D laser scanning .....................................................4 3.3 Existing data sources .................................45 1 Laser Scanning Technology .........7 3.4 Scale of the subject ...................................46 1.1 Scanning hardware ......................................7 3.5 Accuracy and resolution ............................47 1.2 Scanning systems ......................................15 3.6 Georeferencing ...........................................47 1.3 Scanning software .....................................19 3.7 Site conditions ...........................................49 1.4 Computers ..................................................23 3.8 End products ..............................................50 3.9 Budget ........................................................51 2 Laser Scanning Procedures........25 3.10 Alternative methods ..................................51 2.1 Data collection ...........................................25 2.2 Data processing .........................................32 2.3 Data management .....................................40 4 Case Studies ..............................54 Case Study 9: Belsay Castle – laser scan survey.................................................74 Case Study 1: Martins Bank – scan to BIM project .............................................54 Case Study 10: Navajo National Monument – laser scanning and tactile 3D model .................77 Case Study 2: Rhineland – countermarks on Roman coins ..........................56 Case Study 11: Oxford – BIM survey for heritage ......................................80 Case Study 3: The Parthenon Frieze – comparative 3D scanning of the original Case Study 12: Leicester Cathedral sculptures and historical casts ............................58 – scanning the interior ............................................. 82 Case Study 4: Cast Cantabria Case Study 13: The Roundhouse – rock art in El Mirón Cave ....................................61 – reality capture survey .........................................85 Case Study 5: The Iron Bridge Case Study 14: Priory House – 3D modelling .......................................................64 – laser scanning and modelling ...........................88 Case Study 6: Liverpool Street Station Case Study 15: The Barley Hall Hub – BIM survey ...........................................................67 – scanning of archaeological artefacts ................91 Case Study 7: Tregony Case Study 16: London – survey of a historic walled garden ....................69 – highway mobile mapping ...................................93 Case Study 8: Uphill Manor – combining terrestrial laser scan and aerial SfM point cloud data .............................................71 5 References .................................95 6 Glossary ....................................97 7 Where to Get Advice .................100 7.1 Charters and guidance ............................100 7.2 Organisations ...........................................100 7.3 Books ........................................................101 7.4 Journals and conference proceedings ...102 7.5 Websites ...................................................102 7.6 Training .....................................................104 7.7 Contact Historic England ........................110 Acknowledgements ..........................111 Introduction Document outline and objectives of technical jargon, acronyms and abbreviations, and these are explained in the glossary. The The guidance presented in this document should case studies illustrate a range of interesting provide the necessary information to use laser applications and describe the varied laser scanning appropriately and successfully for scanning and other techniques used to heritage projects. It is hoped that from the advice provide appropriate solutions to fulfil a specific given on how the method works and when it survey brief. should be used, archaeologists, conservators and other cultural heritage professionals unfamiliar with the approach can make the best possible use Metric survey of this now highly developed technique. Knowledge of the position, size, shape and After a brief introduction defining laser scanning identity of the components of a historic building and its uses and limitations, section 1 goes on to or site is a fundamental part of a project related describe the different laser scanning technologies to the conservation of cultural heritage. The and systems, both hardware and software, information provides a detailed framework for available to users. Section 1 also introduces the assessment of the site’s significance, a basis some of the advances made in equipment and for further conservation analysis and, potentially, associated software since the previous edition. by using the survey within the process known The methods used to collect, process and manage as building information modelling (BIM), a the laser scan data are presented in section 2. structure to which the historical documentation Section 3 then describes how the user can specify associated with the site can be attached. For a survey (in-house or commissioned) to achieve example, knowing the size and shape of a mound the intended outcomes. Laser scanning is a very or barrow located in a historic landscape can help capable and flexible technique but in many cases archaeologists identify its significance; a stone by no single survey tool offers a complete solution, stone computer-aided design (CAD) drawing of a and other methods of three-dimensional (3D) cathedral elevation provides valuable information data capture may be required. For this reason for an architect to quantify the conservation complementary or alternative methods are effort; or, by repeating surveys, a stone carving briefly described in section 3.10. Some of the can be monitored for its rate of erosion, which advice provided within sections 2 and 3 can will assist the conservator in determining the also be applied generally to methods other than appropriate protection. Traditionally presented laser scanning. This especially applies to data as drawings and latterly in two-dimensional management and the consideration of scale, (2D) CAD form, the information is increasingly accuracy and site conditions. being delivered as 3D data for further analysis, modelling and visualisation. No single document can provide all the relevant information on a subject, and section 4 offers The choice of survey method can be guided by suggestions for further reading, guidance and considering the size of the object, its complexity relevant organisations. Metric survey is a world and its accessibility, but constraints may arise <