State of the Art of HBIM to Develop the HBIM of the HeritageCare Project

The European project HeritageCare aims to develop a methodology to help managers preserve historic monuments. The methodology developed integrates the advantages of HBIM (Historical Building Information Modelling): 3D visualization, grouping of information (history, diagnostics, videos, etc.) under the same object, help with monitoring of maintenance, help with the planning of works, etc. This article develops in a first part the state of the art on the HBIM and its use: realization of numerical model (tools and database of objects), help with the maintenance, identification of the risks associated with the realization of the works. The second part is devoted to the presentation of the HeritageCare project: context and challenges, content and development of the HBIM part.


Introduction
The HeritageCare project aims to help preserve historic monuments (classified and inventoried) by developing a diagnostic methodology based on BIM.This methodology is intended for owners of historic monuments and is interested in movable and immovable objects; it supports the missions of the DRAC.Outputs of this methodology will be: a regular diagnosis (visual and instrumented) of the state of their monument, recommendations in terms of routine maintenance and work to be undertaken, a management tool for the status of their monument.This paper presents a state of the art of BIM applications that can be useful for the project developed, namely: HBIM (Heritage Building Information Modeling), risk analysis and maintenance methods.In a second step, the context of the project, the different levels of management planned and the development of HBIM proposed will be presented.

I. State of the art
The problems of preservation of historic monuments and the different management policies of these monuments are described by F. Choay (1996Choay ( , 2009) ) and J.P. Thibault (2009).Murphy et al (2013) define Historic Building Information Modeling (HBIM) as a library of parametric objects based on historic architectural data, in addition to a mapping system for plotting the library objects onto laser scan survey data.D. Littlefield (2017) proposes, in the following table, a comparison between the contributions and expectations of BIM and HBIM.What is retained for the HeritageCare project is that the digital model must represent the building as it is built, that it must be able to contain all the information useful for its maintenance, including the identification of all defects (qualitatively and quantitatively).
Table 1.Comparison of BIM and HBIM (Littlefield, 2017) Counsell et al. (2003) illustrates the different information that is succinct to be included in a HBIM.All of this information is available in France, but generally in paper form or dispersed in different databases.The interest of HBIM is then to bring together all the information useful to all stakeholders in the maintenance of historic monuments.
Figure 1.Different kind of information included in HBIM (Counsell et al., 2003) According to Sabry Hegazi (2017), HBIM can be an important tool in managing information for a group of buildings and sites, as it provides these benefits:  urban documentation in order to produce accurate land use,  demographic maps creation as output to monitor large-scale sites and heritage cities,  monitoring of urban growth by comparing satellite images,  coverage of historic sites documentation by an infinite number of accurate photos that can be produced by different satellites at the same time,  utilizing a variation of ultrasonic waves and frequencies to document invisible sites and reveal undiscovered desert heritage districts,  saving documentation process time and money as well as human resources,  enabling compatible documentation data for large sites in good quality.
In this section, we will successively discuss the state of the art relating to Heritage Building Information Modeling (HBIM), the risk analysis associating BIM and the maintenance methods using BIM.

I.1. State of the art of HBIM
HBIM papers can be divided into three categories: those dealing with measuring equipment to create a digital model, those relating to object libraries and those considering an approach to the preservation of historic monuments.
The problem for the HeritageCare project is how to obtain the 3D geometry of the works (what hardware, what software?),How to associate the information gathered during the preliminary studies (environment, construction and reconstruction phases, degradations, etc.)., how to use this model to define and program maintenance operations ?
In terms of helping to create digital mock-ups, Helena Rua (Rua and Gil, 2014) explains the approach taken to model a historical monument that is difficult to access.The proposed approach is summarized in the following figure.This approach uses geolocation, a library of objects and digitization.(Rua and Gil, 2014) These authors also propose a comparison of software used to model historic buildings.This comparison is detailed in the following table.
Table 2. Comparison of software used to model historic buildings (Rua & Gil, 2014) Ahmad Kaik (2017) also proposes a digital mockup approach based on a laser survey.Once the images are captured and processed, they are assembled to create the digital model.This approach, which also relies on an object library, is specified in the following figure.

I.2. State of the art of risk analysis using BIM
HeritageCare project participants are used to applying risk analysis methods to identify the causes of monument degradations, anticipate future degradations and thus define optimal maintenance solutions.The aim of this state of the art is to see if interesting developments have been proposed by the BIM community in this area of risk analysis.
Yang Zou et al. (2015) offers a review of risk analysis methods using BIM.It is synthesized in the following table.
Table 4. Review of risk analysis methods using BIM (Zou et al., 2015) Another of BIM with regard to risks is to identify the construction phases that may cause accidents.Sijie Zhang (Zhang et al., 2015) defines a set of rules for checking the presence of security elements during different phases of construction.This article looks at analyzing the effectiveness of BIM in this approach by comparing a manually conducted risk analysis with a risk analysis performed using BIM with built-in security verification rules.
The article (Zhang et al., 2013) details the implementation of these security rules in a BIM model.The principle of the developed method is presented in the following figure.Several safety rules are defined, as for example the required height of security fence.The building model is checked as regards this rules.When irregularities are observed, corrective actions are proposed.2017) proposes a method of energy analysis of existing buildings based on BIM.In this perspective, proposes a review of all the approaches using BIM allowing the verification of buildings.This review is summarized in the following table.
Table 5. Review of methods for the verification of buildings, using BIM (Ghaffarian Hoseini et al., 2017) In the context of historical monuments, infrared thermography can be used to locate moisture-type defects that can cause damage to stones, for example.
Serge Chardon et al. (2016) also proposes an energy evaluation approach for buildings, but intended for individual homes.
Ibrahim Motawa et al. (2013) suggests associating a knowledge base of maintenance carried out on a set of case studies, so via the BIM, to propose appropriate maintenance approaches when similar pathologies appear on the building course of study.The structuring of the proposed approach is detailed in the following figure.This paragraph is devoted to the presentation of the context and objectives of the project, to the different management levels envisaged as well as to the HBIM principle that will be developed.

II.1. Context and objectives of the HeritageCare project
The HeritageCare project is an Interreg Sudoe project involving Portuguese partners (University of Minho, Regional Directorate of Culture of the North, Computer Graphics Center), Spanish (University of Salamanca, Foundation Santa Maria La Real, Andalusian Institute of Historical Heritage) and French (Clermont Auvergne University and University of Limoges).These national consortia strengthen these institutional partners.The French consortium includes: -The Pantheon Architecture Workshop (architectural firm), -Louis Geneste (business of rehabilitation of historical monuments), -Pascal Parmentier (heritage architect), -National School of Architecture of Clermont-Ferrand, -The Auvergne Rhône Alpes region (representatives of the managers), -The inventory service of Limousin, -The DRAC.
This project started in July 2016 for a period of three years and aims to make the non-profit entity created under this project sustainable.
The HeritageCare project was born following two observations.The first finding is the lack of an appropriate heritage management system, which includes monitoring, inspection and preventive maintenance.The second finding is the need to develop a system of preventive conservation of historic buildings, including unclassified buildings.
The objective of this project is to set up a non-profit entity to: -Sensitize owners of buildings of historical and cultural value to carry out inspections and preventive maintenance procedures, -Develop and apply new and advanced inspection technologies for the diagnosis and management of built heritage preservation, -Involve society, the scientific and technical community, public institutions and the conservation sector in a more efficient and sustainable way for the protection of historical and cultural heritage.
This project, for the French part, is interested in the movable and immovable heritage of historical monuments classified and inventoried regions of Sudoe space: Auvergne Rhône Alpes, New Aquitaine and Occitanie.
II.2.Levels of management levels of management are envisaged within the framework of this project, which are associated with different diagnostic techniques (visual, destructive and non-destructive auscultation, etc.) and a level of detail and more or less important information.These three levels are shown schematically in the following figure.
As part of this project, it is planned to diagnose 60 historical monuments (20 in each country).Level I diagnosis will be carried out on 20 monuments.Of these twenty monuments, five will be diagnosed at level II and one will be studied at level III (realization of a HBIM).
The first level of management is the completion of a thorough inspection (mainly visual) according to a protocol that will be defined within the project.These inspections will be carried out regularly (with a period of 1 to 3 years).The results of this first level of management will be a report on the state of conservation of the movable and immovable elements of the buildings as well as recommendations regarding urgent or short term interventions.The second level of management leads to: -A complete geometric survey of the photogrammetry device (or 3D laser) using robotic units or drones (terrestrial and aerial).This type of result is illustrated in Figure 4: the different steps -measurement and assembly -of a photogrammetry are detailed; -Information collection and integration of Level I investigations and complete additional inspections (position sensors, technical reports, preventive conservation); -A classification of the inventory of movable heritage, as illustrated in Figure 3.The third level of management is to use a hBIM model that will include all the information from: -Geometry, -Materials, -Conservation state, -Integration of information from management levels I and II, -Structural and non-structural monitoring systems, -Conservation / maintenance plan: preventive tasks (types and quantities), -Financial management.
The following figure illustrates the type of result that could be obtained at the end of a level III management level.The developed hBIM will make it possible to locate the different historical monuments on a territory, to propose analyzes (thermal, structural, etc.), to locate the diagnostic results of levels I and II, to represent the phasing of the work to be done, etc.The creation of hBIM digital mockups requires the development of a library of specific objects for historical monuments.The structuring of this object library can be based on the thesaurus of the naming of architectural works and spaces developed on the one hand and on the thesaurus of the naming of movable objects on the other hand.The properties associated with these historical objects will be: their dimensions, their shape, their material, their date of construction, the environmental agents soliciting, the possible actions on the other objects and as far as possible the kinetics of degradation of the phenomena affecting these objects.
Laser 3D analysis and photogrammetry, conducted at the Level II diagnostic level, will provide the point cloud for the development of a digital mock-up and the graphic representation used in the communication for the promotion of this monument.
The digital models of the monuments diagnosed would be the support of the operational follow-up of the diagnoses insofar as they would allow: -To know the state of the monument through the results of level II diagnoses, -To know the aging of the monument, that is to say to know the dates of appearance of the phenomena of degradation and thus to foresee the maintenance work to be programmed, -To help with the programming of the works (via metrics, prices, etc.).
The storage of information consists in grouping together in the form of a database attached to the digital model, all the useful information relating to a monument diagnosed: -Historical documents on construction, -Regulatory texts for monitoring and carrying out maintenance work, -Manual of maintenance and monitoring of the monument, -Methods of carrying out maintenance work, -Diagnostic reports made, -Etc.
The graphic 3D modeling of a historic monument allows to increase the promotion of this monument and to make accessible to the general public inaccessible places since too vulnerable (crypt for example).

Conclusion
This paper develops in a first part the state of the art on the preservation of historical monuments based on the HBIM.HBIM is seen as a way of bringing together all the necessary information (3D representation, history, diagnostics, videos, etc.) to the maintenance.The research developed concerns the techniques used to obtain the 3D models (laser, photogrammetry, scan, radar, object libraries), the diagnostic assistance for the maintenance and the verification of the security for the realization of the works.In a second part, the context, the different levels and the development of HBIM as part of the HeritageCare project are developed.This project is moving towards the creation of a parametric object library, the creation of an information database (diagnosis, history, costs, etc.) related to digital models and the development of a tool help with maintenance planning extracting useful information from digital mockups.

Figure 2 .
Figure 2. Approach to create a virtual model of historical monument(Rua and Gil, 2014)

Figure 3 .
Figure 3. Approach to create a digital model of historical monument based on a laser survey (Kaik, 2017)

Figure 5 .
Figure 5. Approach to create an object database based on cloud of points(Hawas et al., 2017)

Figure 10 .
Figure10.Example of a card of historical monument for helping its maintenance(Biagini et al., 2016)

Figure 11 .
Figure11.Approach of security rules in a BIM model(Zhang et al., 2013)

Figure 13 .
Figure13.Digital model of the Sydney Opera House and its use for maintenance(Linning, 2018)

Figure 15 .
Figure 15.Details of the BIM Module of the figure 14(Motawa et al, 2013)

Figure 16 .
Figure16.Automatic detection of the shape of stones and joints(Valero et al., 2017)

Figure 17 .
Figure 17.Three levels of management considered as part of the HeritageCare project

Figure 18 .
Figure 18.Illustration of diagnostic of management level 1

Figure 19 .
Figure 19.Illustration of the asset classification management level 2

Figure 21 .
Figure 21.Illustration of a management level 3 hBIM template