10.6092/issn.1973-9494/12793
Il rilievo del patrimonio architettonico è fondamentale nella conservazione degli edifici storici per la ricerca scientifica, l'istruzione e il turismo. L'uso dei veicoli aerei senza pilota e le tecniche di scansione laser terrestre sono essenziali per il rilevamento e la mappatura del patrimonio architettonico. Negli ultimi anni l'abbinamento del Building Information Modeling (BIM) con gli studi sul patrimonio è stato presentato come Historic BIM (HBIM) che, integrato con UVA e TLS, permette di affrontare in modo più efficiente la gestione e la tutela edifici. Questo documento tratta l'integrazione di immagini UVA con l’insieme punti scansionati con laser per costruire un modello architettonico 3D per la documentazione di edifici storici cinesi. In particolare, il metodo testato nel caso di studio del villaggio tradizionale, Hexinwu, Cina, può contribuire ulteriormente all'analisi, valutazione e pianificazione del patrimonio di questa straordinaria struttura architettonica, aumentando così la sua importanza storica per il futuro.
application/pdf
1973-9494
12793
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Kun Sang
https://creativecommons.org/licenses/by/3.0
Conservation Science in Cultural Heritage
traditional village
From Site Survey to HBIM Model for the Documentation of Historic Buildings: the Case Study of Hexinwu Village in China
Text.Serial.Journal
https://conservation-science.unibo.it/
20
Articles
2021-05-13
2021-04-27
2021-05-13
2021-05-13
111-123
CSCH
Kun Sang
2020
10.6092/issn.1973-9494/12793
111
Department of Historical and Geographic Sciences and the Ancient World (DiSSGeA), University of Padua, Italy
1973-9494
traditional village
en
123
From Site Survey to HBIM Model for the Documentation of Historic Buildings: the Case Study of Hexinwu Village in China
https://conservation-science.unibo.it/article/download/12793/12509
20
F    ROM SITE SURVEY TO HBIM MODEL FOR THE
     DOCUMENTATION OF HISTORIC BUILDINGS:
     THE CASE STUDY OF HEXINWU VILLAGE IN CHINA

   Guiye Lin *, Andrea Giordano
   Department of Civil, Environmental and Architectural Engineering (DICEA)
   University of Padua, Italy

   Kun Sang
   Department of Historical and Geographic Sciences and the Ancient World (DiSSGeA)
   University of Padua, Italy


   Keywords: UAV, TLS, HBIM, digital heritage, traditional village




   1. Introduction

    The meaning of the protection of cultural heritage is self-evident and has inestima-
ble significance for our cultural inheritance and development. Viewed as a kind of irre-
placeable cultural heritage and non-renewable resource, historic buildings can also be
regarded as a symbol of the cities they are part of, reflecting their cultural identities and
histories. However, in the modern wave of urban construction, architecture has tended
to adopt a quasi-uniform style and, as a result, has lost much of its character. In addi-
tion, historic buildings need systematic maintenance, adaptive reuse and comprehen-
sive redevelopment, as well as interdisciplinary cooperation to protect their aesthetic,
cultural and historical values. Against this background, an increasing number of modern
technologies and theories have been introduced into the field of the protection and res-
toration of historic buildings. For example, digital technologies, such as Building Infor-
mation Modeling (BIM) and Augmented Reality (AR) are being used for the virtual res-
toration of architectural heritage and represent an important milestone in this area.
    In comparison, traditional documentation techniques, such as hand drawing, 2D
photography and manual measuring with traditional devices (tapes, levels, and the-
odolites, etc.), cannot completely meet the requirement of reproducing the finer details
of heritage artefacts with extreme precision, and may also have some negative or phys-
ically destructive impact on them [1]. In China, architectural heritage always contains
numerous elements and decorations with a great many details which can easily be
influenced by survey instruments. The application of 3D modelling to historical struc-
tures has therefore facilitated the observation of these finer architectural details and
enabled us to view them from various distances, angles and scales. It has ultimately
proved to be an effective technical support for the digital surveying, documentation, pres-
ervation and visualization of architectural heritage, and has already become a hot re-
search topic in architecture and heritage studies [2].


   * Corresponding author: guiye.lin@studenti.unipd.it
                                                                                                                                           These advanced techniques have been mainly developed based on terrestrial
G. Lin, A. Giordano, K. Sang - From site survey to hbim model for the documentation of historic buildings: the case study of hexinwu



                                                                                                                                       and aerial sensing systems such as Terrestrial Laser Scanning (TLS) and Unmanned
                                                                                                                                       Aerial Vehicles (UAV) [3]. Several studies have integrated them to achieve more ac-
                                                                                                                                       curate or complete geometric surveying for heritage modeling, digital interpretation,
                                                                                                                                       representation, conservation and many other issues [5]. TLS has the advantage of
                                                                                                                                       collecting data with higher accuracy and reducing operating time without having to
                                                                                                                                       touch the measured objects, thus causing less physical damage to the heritage itself.
                                                                                                                                       Additionally, a UAV mounted high-resolution digital camera can obtain images with
                                                                                                                                       high spatial resolution and high-quality 3D models but has lower manpower costs
                                                                                                                                       compared with other methods [6]. Being non-destructive and with these added char-
                                                                                                                                       acteristics, the application of TLS and UAV in the field of heritage protection has
                                                                                                                                       substantially increased.
                                                                                                                                           With the development of this sensing equipment, the concept of building information
                                                                                                                                       modeling (BIM) has evolved significantly. BIM is not only a tool for modelling, but also
                                                                                                                                       provides a platform for the organization, optimization, analysis and management of in-
                                                                                                                                       formation, with functions of visualization, simulation and cross-platform coordination.
                                                                                                                                       It has been applied to every process of architectural projects from various scales and
                                                                                                                                       processes, including design, construction, management, maintenance as well as the
                                                                                                                                       restoration of single buildings, infrastructures or building clusters [7]. The term “Historic
                                                                                                                                       Building Information Modelling (HBIM)” was proposed within the heritage sector as “a
                                                                                                                                       novel prototype library of parametric objects, designed specifically for mapping these
                                                                                                                                       objects onto point clouds and survey data” [8]. The general working process of HBIM
                                                                                                                                       starts from a digital survey, in which a set of points with defined coordinates, called
                                                                                                                                       “point clouds” are obtained with geometric and colorimetric information. After process-
                                                                                                                                       ing, they can be transformed into parametric smart object libraries in BIM software for
                                                                                                                                       further modelling. Based on the BIM model for historic buildings, the classified building
                                                                                                                                       components can be easily identified and analyzed for conservation purposes [9].
                                                                                                                                           This paper takes some historical buildings (dragon houses) in Hexinwu village as a
                                                                                                                                       research subject using HBIM as the main methodology. The aim is to introduce these
                                                                                                                                       digital technologies into the protection of historical buildings in Chinese traditional vil-
                                                                                                                                       lages. This multiple survey method, including data processing, presentation and docu-
                                                                                                                                       mentation, focuses on the integration of TLS and UAV photogrammetry to acquire rap-
                                                                                                                                       idly comprehensive data of the diverse elements of the historical buildings. The TLS is
                                                                                                                                       used for data acquisition of the building facades, while the UAV is used for scanning
                                                                                                                                       the roof parts. Furthermore, the process of dealing with point clouds and building para-
                                                                                                                                       metric objects in BIM is discussed. Finally, the built model, based on the fine point cloud
                                                                                                                                       data, is an important update in the documentation of Hexinwu village. In addition, the
                                                                                                                                       visualization of heritage in 3D/AR/VR format is also beneficial for heritage tourism and
                                                                                                                                       further research. Thus, this project is not only useful and meaningful for the future plan-
                                                                                                                                       ning of the protection of Hexinwu village, it can also be a reference for other Chinese
                                                                                                                                       architectural heritage with complex decorations and complicated spatial compositions,
                                                                                                                                       such as the traditional ancient Chinese courtyard used in residential compositions in
                                                                                                                                       Beijing, as well as in other temples and palaces.


                                                                                                                                          2. Study area

                                                                                                                                          Hexinwu village (24.228836° N, 114.819558° E) is located in Dahu town, Guangdong
                                                                                                                                       province in Southern China (Figure 1), which is the birthplace of the Hakka culture (a


                                                                                                           112
branch of Chinese culture in the south of China), and where there are a number of
important historical Hakka villages. Some archaeological relics (land lease documents
from the Qing Dynasty) have already been found in Hexinwu village, but the village has
not yet been included in the national list of historical villages, and its current status of
protection is not optimistic.
     This study focuses on a cluster of ancient Chinese buildings in the center of this
village, which covers an area of nearly 3000 m2. As one of the most typical historical
villages composed of dragon houses with Chinese architectural characteristics,
Hexinwu village was originally built during the period 1368-1644 because of its con-
venient location near the post road in Guangdong. It was enlarged several times by
a family named “HE”, a eunuch family, in the late 19th century. With a history of
more than 300 years, the central buildings in the village serve as the ancestral
houses of the HE family, which are enclosed by wall-structures composed of two
semicircles. The front half of the circle is a crescent fishpond and the other half of
the circle is the residential house, which symbolizes the shape of coiling dragons,
and thus they are called “dragon houses” (Figure 2). Historic buildings in Hexinwu
village combine artistic values with practical functions. The main halls serve as
spaces for ritual or other traditional activities, with the front hall housing the ances-
tral shrine of the family [10].
     Unfortunately, due to the rapid population growth, urbanization, pollution and mod-
ernized lifestyle in Guangdong, the survival of the existing buildings in this village is
threatened. Some of the buildings at the edge of the village have already been de-
stroyed, while others have been partially damaged and can no longer be used. But the
central houses still function as residential buildings for locals, and these are the main
survey objects in this study. The other buildings outside the central area have not been
taken into consideration.




                                                                                                  Conservation science in Cultural Heritage




Figure 1. Location of Hexinwu village in China.    Figure 2. (a) Study area; (b) site photos.


    Nowadays, Hexinwu village is facing great danger because of the current situ-
ation. However, despite their great value and importance, these dragon houses are
seldom studied by Chinese scholars. The government of Guangdong, jointly with
the University of Guangzhou, is currently trying to survey, record, protect and restore
this traditional village. A comprehensive survey to assess the current condition of
the historical buildings and a conservative strategy for the whole village are badly
needed.


                                                                                                113
                                                                                                                                          3. Methodology
G. Lin, A. Giordano, K. Sang - From site survey to hbim model for the documentation of historic buildings: the case study of hexinwu




                                                                                                                                           The whole research process can be classified in five steps (Figure 3). The first step
                                                                                                                                       was to determine the survey plan. Then, the TLS was introduced to scan the facades
                                                                                                                                       of the village, while the UAV was used to capture photos to eliminate the occlusions
                                                                                                                                       from the TLS survey, mainly the roof parts. In order to achieve rapid and comprehensive
                                                                                                                                       data collection, a flight plan for the UAV was designed and carried out and the TLS scan
                                                                                                                                       positions were settled to cover the entire study area with the minimum number of scan
                                                                                                                                       positions and aerial photos. Then, the raw data of the two methods were processed to
                                                                                                                                       get two individual point clouds (TLS point cloud and UVA point cloud). After using the
                                                                                                                                       common reference of these point clouds to assist the fusion (registration) of the TLS and
                                                                                                                                       UVA, the HBIM model of the central dragon houses in Hexinwu village were obtained
                                                                                                                                       and were ready for further analysis and applications.




                                                                                                                                                                     Figure 3. Workflow in this study.


                                                                                                                                          3.1. Data acquisition with terrestrial laser scanning

                                                                                                                                           The digital tools (TLS and UAV) make data collection in this project fast and compre-
                                                                                                                                       hensive. For the terrestrial scanning of the dragon houses, a 3D LiDAR scanning instru-
                                                                                                                                       ment called Trimble TX8 was employed (Figure 4a). In general, a LiDAR emits laser
                                                                                                                                       pulses for measuring distances, obtaining information about the texture of the building
                                                                                                                                       materials and their degradation. A TX8 scanner has a scanning range of 120 meters, a
                                                                                                                                       360° (horizontal) and 270° (vertical) field of view and it can capture scans at a speed of
                                                                                                                                       up to 1 million points/sec. Compared with other tools, the main characteristics of this
                                                                                                                                       scanner are its high precision, high resolution, high speed and the fact that operating
                                                                                                                                       times are reduced and it has no destructive effects on the objects under examination. In
                                                                                                                                       addition, it is integrated with a digital color camera, and during the scanning process,
                                                                                                                                       can obtain images with RGB color information and a capacity of 1920*1920 pixels [11].


                                                                                                        114
            Figure 4. (a) The Trimble TX8; (b) The scanner positions and field-of-view.


    The whole site was surveyed by TX8 from a total of 35 scan stations. The positions
of the scanner are showed in Figure 4b, considering that there is enough overlap (more
than 40%) between every two consecutive scans. Furthermore, a side overlap of
30%-50% between the adjacent scans ensures an accurate 3D point cloud model [12].


   3.2. UAV




                                                                                              Conservation science in Cultural Heritage
     Due to the limitations in height of the TX8 scanners, the roofs of the buildings
could not be well recorded. For this reason, a UAV was employed as a low altitude
aircraft, and introduced as a supplementary tool for the laser scanning to produce im-
ages from different views. The UAV is a flexible, low-cost, high frequency tool, equipped
with a high-resolution camera and a GPS device, which generates diverse types of geo-
graphical products and highly detailed models [13]. For this aerial survey, a DJI Phan-
tom 4 Pro was used and is a photography drone designed by Da-Jiang Innovations
in China, with an onboard camera equipped with a 1-inch 20-megapixel CMOS sen-
sor and an FOV 84° 8-mm lens. The Phantom 4 also has a GPS device and optical
recognition system. This combination facilitates further photo alignment in later pro-
cessing.
     In order to acquire more detailed images of Hexinwu village, two different types of
flight plans were combined. The first one with a nadiral configuration of the camera and
the second with an oblique configuration [14]. Each type of flight ensured an overlap
between consecutive photos of at least 70% (Figure 5). The speed of flight was nearly
1.5m/sec and the average flight altitude was 25m; the lens covered an area of approxi-
mately 4 hectares with one photograph, with an image resolution of about 3 cm/pixel.
The detailed flight parameters, including the records of flights, type of drone, sensor,
number of photos, etc. of both flights are shown in Table 1. For the study site, a total
number of 775 photographs were taken.


                                                                                            115
G. Lin, A. Giordano, K. Sang - From site survey to hbim model for the documentation of historic buildings: the case study of hexinwu




                                                                                                                                                                        Figure 5. Flight path of the UAV.


                                                                                                                                       Table 1. UAV flight specifications

                                                                                                                                          Flight date                  2019/11/03            2019/11/04       2019/11/05

                                                                                                                                          Duration                     20 mins               22 mins          25 mins

                                                                                                                                          Altitude                     25 m                  25 m             25 m

                                                                                                                                          UAV type                     Quadcopter            Quadcopter       Quadcopter

                                                                                                                                          Optical sensor               DJI                   DJI              DJI

                                                                                                                                          Resolution                   3.64 mm               3.64 mm          3.64 mm

                                                                                                                                          Dimension                    6.3 * 4.7 mm          6.3 * 4.7 mm     6.3 * 4.7 mm

                                                                                                                                          Pixel                       1.55 µm                1.55 µm          1.55 µm

                                                                                                                                          FOV direction                Nadir                 45°              45°

                                                                                                                                          GSD                          0.56 cm               0.56 cm          0.56 cm

                                                                                                                                          Number of photos             300                   255              250

                                                                                                                                          Distance                     200 m                 220 m            250 m



                                                                                                                                            3.3. Pre-processing of point cloud

                                                                                                                                           The point data acquired from the TLS and UAV need to be preprocessed indepen-
                                                                                                                                       dently to form the point cloud in different software due to their different characteristics.
                                                                                                                                       The pre-processing stage can be divided into two sections: in the first, the data col-
                                                                                                                                       lected from the scan positions using TLS were processed with “Trimble Realworks”,
                                                                                                                                       provided by Trimble, for transforming the scan data into 3D deliverables, as well as
                                                                                                                                       “Autodesk Recap”, designed by the Autodesk Company with tools for systems integra-
                                                                                                                                       tion, workflow optimization and BIM modeling; in the second, the UVA photos were
                                                                                                                                       processed by Photo Scan Pro software, which performs the photogrammetric process-
                                                                                                                                       ing of digital images and generates 3D spatial data.


                                                                                                        116
    In Trimble Realworks, multiple scans were imported with appropriate positions con-
nected to each other according to their respective coordinates. After converting the
point format into E57 (a compact and vendor-neutral format for storing point clouds),
they were loaded into the Autodesk Recap. The cloud-to-cloud registration technique
was applied, which did not need any targets but only point clouds aligned to each
other by extracted features within the overlap area of each point cloud. After registra-
tion, the color of the point cloud data was also captured by the integrated digital cam-
era (Figure 6) [15]. Due to an overlap between pairwise scans (>40%), the registration
of TLS data produced a dense point cloud. As a result, this point cloud had a spatial
resolution of 1 cm and was registered with the 3 spherical target references. The aver-
age error of registration point was 2.0 mm and the maximum error was 3.5 mm.
    The data captured with the UAV were imported into the Photo Scan Pro software
for automatic processing, including aligning photos, optimizing alignment and building
dense clouds. The processing algorithm was based on the Structure from Motion meth-
od (SfM). and is a photogrammetric method for creating 3D models of features from
overlapping 2D photographs taken from different positions and orientations to rebuild
the scenarios. In this process 500,758 tie points were found. The median reprojection
error was 0.21 pixel and the root mean square (RMS) of reprojection errors was 0.51
pixel. The output of the UVA point cloud is shown in Figure 7.




                                                                                             Conservation science in Cultural Heritage
                       Figure 6. Point cloud of east side of buildings.


   3.4. Integration of point clouds

    The combination of the UVA and TLS point clouds make up a whole. Obviously, the
UAV flights captured the top view of the buildings because of the height of its sensors,
while the TLS tool scanned the side view of the buildings. The parts of the roof cap-
tured by the UAV, restored the data missing from the TLS. By combining the two sets
of data, a complete data model of the whole building area was produced. Thus, the two
individual point clouds of TLS and UAV were processed to integrate them. Merging the
two individual point clouds was conducted using the Iterative Closest Point algorithm
(ICP), an algorithm to minimize the difference between two point clouds. It includes
repeatedly matching the closest point in the reference and estimating the minimum
translation, to transform the source points and re-associate them. The final product is


                                                                                           117
                                                                                                                                       an accurately dense 3D point cloud of the historical buildings in the center of Hexinwu
G. Lin, A. Giordano, K. Sang - From site survey to hbim model for the documentation of historic buildings: the case study of hexinwu



                                                                                                                                       village, containing detailed information of both the top view and side view of the hous-
                                                                                                                                       es (Figure 8).




                                                                                                                                                                    Figure 7. Point cloud of roof parts.




                                                                                                                                                   Figure 8. Aerial view of the integrated point cloud from TLS and UAV.


                                                                                                                                          4. Modeling in BIM

                                                                                                                                           Unlike other cultural relics, ancient Chinese buildings have the characteristic of be-
                                                                                                                                       ing large in size and having a complex structure with an abundance of details. Gener-
                                                                                                                                       ally speaking, a single Chinese building can be composed of dozens to hundreds, or
                                                                                                                                       even thousands of components or elements. In BIM, building information is considered
                                                                                                                                       directly as the management object, and building components are basic geometric units.
                                                                                                                                       Each type of component corresponds to one “family” group (a method of classification).
                                                                                                                                       Because of the same architectural style and structure of the houses in the village, the
                                                                                                                                       rule for classifying the building components of the dragon houses is according to their
                                                                                                                                       position and geometry in this project. For example, the doors, windows and walls of
                                                                                                                                       the houses can be regarded as a family of “retaining structures”; the building of these


                                                                                                        118
“families” was finished before the BIM modelling process started. Finally, the models of
all the families were assembled as a complete building, using a structure called “scaf-
folding” to organize all the families. Additional features can be attached to the model of
the building components, such as structure, composition, material, shape, quality, size,
color and so on, which will serve for further architectural analysis. The whole paramet-
ric BIM modelling workflow of dragon houses in Hexinwu village can be summarized as
shown in Figure 9:




                             Figure 9. HBIM Modeling process.


    According to the finished site survey, the wooden structure of dragon houses is not
complicated. Using the analysis of all the built point clouds, the architectural compo-
nents of the Hexinwu houses can be classified into four families, namely foundation,
wood structure, retaining structure and roof. Each building component can be viewed
in BIM and coded by ID numbers, for example, the window components are listed as
W_1, W_2, etc. After distinguishing the difference among these components, the com-
ponent families and their further subclassifications are shown in Figure 10.




                                                                                               Conservation science in Cultural Heritage




                   Figure 10. Architectural components of dragon houses.


    Afterwards, a library of corresponding parameterized components was established.
Point cloud data provides accurate geometric data for the “family” models of the build-
ing components. Ancient Chinese buildings have a modular scale and characteristic
combination involving a “parameterized” design and construction process, based on
specific components. For example, the pillars in every house in Hexinwu follow the
same module. Establishing a parametric family model and setting the main driving pa-
rameters can standardize the shape and scale of every component in the houses. “Revit”


                                                                                             119
                                                                                                                                       (a professional BIM software) allows each family object to be assigned several attributes
G. Lin, A. Giordano, K. Sang - From site survey to hbim model for the documentation of historic buildings: the case study of hexinwu



                                                                                                                                       related to its geometrical structure, composition and other properties.
                                                                                                                                           In the last step, each family was fitted into the appropriate position in the BIM model
                                                                                                                                       using a “hosting” technique [16]. In the case of the dragon houses in Hexinwu, each main
                                                                                                                                       wall of the structure was considered as a “host” of the modelled family; each family
                                                                                                                                       was, therefore, manually placed in the wall according to its position in the point cloud.
                                                                                                                                       The final BIM model is illustrated in Figure 11.
                                                                                                                                           The resulting HBIM model is a data-rich, object-oriented, intelligent and parametric
                                                                                                                                       digital representation of the dragon houses in Hexinwu village. This makes all the in-
                                                                                                                                       formation (views and data) on Hexinwu easily available and can appropriately meet the
                                                                                                                                       various needs of its users. It can also be extracted and analyzed to generate informa-
                                                                                                                                       tion to make decisions and to improve the process of preservation of architectural
                                                                                                                                       heritage in the future [17].




                                                                                                                                                             Figure 11. Final HBIM model of Hexinwu village.


                                                                                                                                           BIM models, moreover, follow the principle of “information interoperability”. The data
                                                                                                                                       format provided by BIM is an international structured form and proper standard data
                                                                                                                                       format – IFC (Industry Foundation Classes). Developed for the exchange and sharing
                                                                                                                                       of building information during projects, the IFC provides open data file formats about
                                                                                                                                       architectural, building and construction information and is widely recognized by many
                                                                                                                                       international companies working in these fields. With the uniform IFC model, different
                                                                                                                                       software environments share the same data standard, and the building information can
                                                                                                                                       interact in various environments [18]. Thus, the built HBIM model of Hexinwu village
                                                                                                                                       can be easily shared with other scholars for further studies.


                                                                                                                                          5. Conclusion

                                                                                                                                            In this study, Hexinwu village, one of the most famous and important ancient Hakka
                                                                                                                                       villages in China, was taken as an example to describe the process of digitally docu-
                                                                                                                                       menting Chinese architectural heritage, from the initial use of multiple site-survey tech-
                                                                                                                                       niques to the final HBIM model. The study describes how precise surveys were made
                                                                                                                                       and documentation was produced using scanning technology, i.e. the TLS and UAV


                                                                                               120
systems. Survey methods included various techniques, such as data acquisition, data
processing, data integration and appropriate presentation. Generation of the HBIM mod-
el was obtained starting from collected point clouds, point clouds from laser scanning
and UAV data, to build a detailed HBIM model. HBIM has demonstrated its ability to
capture and record information related to heritage building. It is therefore not only use-
ful for the presentation of the Chinese traditional village, but also shows potential in its
application to other cultural heritage contexts with complex components.
     The HBIM model will provide critical information for the protection of ancient build-
ings and the inheritance of traditional architectural heritage. For example, from the scale
of single heritage building, the internal environment (solar and wind analysis, etc.) can
be stimulated along with other geographic data; from the scale of the village, the spa-
tial arrangement of building clusters can be evaluated and analyzed in a Geographic
Information System (GIS) environment; and from a regional scale, future tourism and
heritage protective planning can be proposed according to the HBIM information [20].
     With thdevelopment of computer technology, related digital technologies will become
even more sophisticated. In the foreseeable future, more digital technologies such as 3D
printing, big data, AR/VR can be used in different combinations as methods for the digital
protection of heritage. Nevertheless, more systematic research needs to be done to
contribute to a more comprehensive digital construction of architectural cultural heritage.


      Acknowledgments

      The research in this paper is funded by the China Scholarship Council (CSC).


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                                                                                                                                             Biographical notes

                                                                                                                                          Guiye Lin is a PhD student at the University of Padua. His field of research focuses
                                                                                                                                       on 3D scanning, UAV, model building and HBIM.

                                                                                                                                           Kun Sang is a PhD student at the University of Padua. His research interests include
                                                                                                                                       railway heritage, Geographic Information Systems (GIS) and cultural heritage.


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    Andrea Giordano is a full professor at the University of Padua, and head of the
Laboratory of Drawing and Representation (LDR) and the Laboratory of Information
Modeling (LIM). His research focuses on the geometric-configurative interpretation of
architectural surfaces; representational codes for the verification of landscape design;
architectural and urban historic transformation, visualization and multimedia represen-
tation.


    Summary

    Architectural heritage surveying plays a fundamental role in the preservation of
historic buildings for scientific research, education and tourism. The use of Unmanned
Aerial Vehicles and Terrestrial Laser Scanning techniques are essential for architec-
tural heritage surveying and mapping. In recent years, the combination of Building In-
formation Modelling (BIM) with heritage studies has been presented as Historic BIM
(HBIM) which, integrated with UVA and TLS, is a technique that is able to deal more
efficiently with the management and protection of historic buildings. This paper focuses
on the integration of UVA images and point clouds from laser scanning to build a 3D
architectural model for the documentation of Chinese historic buildings. In particular,
the method, tested in the case study of the traditional village, Hexinwu, China, can con-
tribute further to the analysis, evaluation and heritage planning of this remarkable ar-
chitectural structure, thus increasing its historical significance for the future.


    Riassunto

     Il rilievo del patrimonio architettonico è fondamentale nella conservazione degli edi-
fici storici per la ricerca scientifica, l’istruzione e il turismo. L’uso dei veicoli aerei senza




                                                                                                      Conservation science in Cultural Heritage
pilota e le tecniche di scansione laser terrestre sono essenziali per il rilevamento e la
mappatura del patrimonio architettonico. Negli ultimi anni l’abbinamento del Building
Information Modeling (BIM) con gli studi sul patrimonio è stato presentato come Historic
BIM (HBIM) che, integrato con UVA e TLS, permette di affrontare in modo più efficien-
te la gestione e la tutela edifici. Questo documento tratta l’integrazione di immagini UVA
con l’insieme punti scansionati con laser per costruire un modello architettonico 3D per
la documentazione di edifici storici cinesi. In particolare, il metodo testato nel caso di
studio del villaggio tradizionale, Hexinwu, Cina, può contribuire ulteriormente all’anali-
si, valutazione e pianificazione del patrimonio di questa straordinaria struttura architet-
tonica, aumentando così la sua importanza storica per il futuro.




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