Towards a standard specification for terrestrial laser scanning of cultural heritage

The use of terrestrial laser scanning for cultural heritage recording is becoming increasingly popular. Although in some cases laser scanning has been met with a degree of scepticism, scanning has, on the whole, been received with a great deal of enthusiasm. This zeal has ensured laser scanning is now at the forefront of many new projects for the documentation of cultural heritage, leading to the need to standardise the outcome of laser scanning surveys to ensure data is collected in a manner that can produce products useful to the end user. The current Metric Survey Specification for English Heritage, the body responsible for preserving and enhancing England’s cultural heritage, contains similar requirements for photogrammetric, non-photogrammetric and topographic survey. This project increases the scope of the specification by introducing terrestrial laser scanning into the surveying workflow. It informs about the advantages and disadvantages of using laser scanning, highlighting the pitfalls of the technique and producing sample datasets that show exemplary practice of laser scanning within the field of cultural heritage recording. Guidelines, for the application of terrestrial laser scanning to cultural heritage, have been formed based on the work. A number of issues surround the definition of such a specification, such as broad range of scales at which laser scanning can be applied, and the black box nature of some of the instruments. In particular this project deals with objects at the “building scale” range, typically surveyed using photogrammetry or rectified photography. The guidelines have been formulated based on three laser scanning surveys, at different English Heritage sites. In order to remove any bias for a particular instrument it was important that different laser scanning systems were considered. After the completion of each survey the draft document was examined and updated. As it is essential that a specification is also a practical guide to implement outside of test projects it was important that the end users of the specification were properly consulted throughout the process. Therefore, a steering committee, whose members represented a cross section of laser scanning practitioners, surveyors and experts in the field of cultural heritage recording in the UK, was formed to provide guidance during the project. The project does not claim to produce the definitive specification for terrestrial laser scanning in cultural heritage as the subject is particularly complex, however it does provide a useful starting point for future discussion and revision. Although the definition of a specification could smother the development of terrestrial laser scanning, this project aims to guide the development of scanning to meet the needs of the end users (archaeologists, architects, building historians amongst others).