REVIEW AND ANALYSIS 43 have transformed the survey speed and enabled rapid file sharing in common work environments. These primary survey drawings form the basis of much of conservation practice, from recording and documentation of the ‘as built’ historic asset through to project visualisation and more. Survey acquisition has been assisted with the increasing and common place use of unmanned aerial vehicles (UAVs, aka drones). These have clear advantages in attaining survey data that is rich, cost effective (often obviating the need for scaffolds and working platforms) and, most importantly, safe. Within the realm of survey and building operation, sensor technology for structural health monitoring and an array of performance monitoring of buildings are also becoming digitally enabled. Traditional methods have indeed become more sophisticated, such as the use of LVDTs for monitoring movement. One of the benefits of digital data acquisition technologies is the ability to combine and overlay their data. For example, infrared thermography for hygrothermal performance analysis can be integrated onto laser scan data; indeed, some modern scanners can even be integrated with thermal imaging. While these technologies and applications are transformational, the data they provide is often not directly actionable without significant manual manipulation and processing with special, often complex, software. This lack of easy access to actionable information (direct actions that can be taken from the data thereby enhancing productivity) limits the potential and arguably hindered digital uptake as the commercial return on investment was limited beyond visualisation, documentation and recording. An additional issue with classical digital technology deployment was a lack of objective guidance in the selection of the systems. For example, laser scanning captured the imagination of the public and practitioners alike. But, while laser scanning is appropriate in a number of contexts, alternative digital reality exists that may be cheaper, faster and result in better digital acquisition capabilities, such as photogrammetry. Current so-called ‘digital’ approaches to information management, albeit facilitated by digital technologies, generally follow similar practice to classical physical document management, with digital documents (PDFs, for example) filed in electronic ‘manila’ folders on the computer, with little to no digital information integration or linkage. Increasing use of BIM is, however, noted in the wider construction sector which is often developed adopting a semantically rich digital model (linking digital information in a unified model). Software choices to author BIM models include ArchiCAD, REVIT, Bentley (Open Buildings Designer and Pro-Structure) or even open-source solutions like Blender. However, the importance of BIM transcends the creation of a model. One of the main reasons for the adoption of BIM is to create structured repositories of all information pertaining to the life of a building. These ‘digital twins’ can support more effective maintenance and conservation decision making. However, BIM repositories need not be complex and, in fact, do not even require 3D models. The heritage sector’s version of BIM is known as HBIM and reflects the increase in complexity in the creation of a model from an already constructed physical asset (as is). The process of creating a model, in this case, often starts with digital data from laser scans or photogrammetry, for example, which is then processed (mostly manually) to generate a BIM model, identifying and modelling the individual building elements. This process is commonly called ‘scan-to-BIM’. The model is semantically rich from this initial modelling step, but can be further enriched through use case - specific element properties which can store numbers, text or even links to other forms of digital data (see Sadeghineko et al, 2018). For all of the perceived benefits of HBIM, its uptake is at present limited. It can be costly, requiring upskilling of the work force and wider practices and may be considered highly risky. In addition, the promise of efficiency can only be realised if the sector universally adopts the same working practices, which is a challenge due to sector fragmentation. That said, it is recognised that technological innovation may disrupt current working practices. The rate of new developments and harnessing of digital technologies will logically increase. The ready-availability of technologies such as handheld scanning and photogrammetry on smart phones is already transforming digital reality capture. This is particularly noteworthy for those in Figure 1: Semantic segmentation results of orthophotos of typical slated roof panels: the aim is for the programme to identify lead and slated areas and other features as distinct elements of the construction. (Reproduced from Lin et al, 2024)
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