1. Introduction
Protecting ancient structures holds significant historical and cultural importance as a crucial component of cultural heritage. The increasing focus on preserving ancient buildings has been driven by advancements in science and technology, leading to the utilization of current technology in this field [
1,
2]. Conventional approaches to preserving old buildings include labor-intensive and time-consuming manual mapping and recording. These methods often fail to provide accurate and comprehensive information. Modern technologies like 3D laser scanning, Global Positioning System (GPS), Building Information Modeling (BIM), and Geographic Information System (GIS) have been employed to preserve ancient buildings, effectively addressing these challenges [
3,
4]. Scientists from various nations have adopted these techniques to investigate the conservation and safeguarding of traditional timber and masonry building materials in their respective countries. They have also utilized these methods to examine the types of damage, restoration principles, and reinforcement techniques employed in ancient timber-framed structures [
5,
6].
Laser scanning employs LiDAR technology to emit laser pulses and measure the time taken for their reflection, creating detailed 3D point clouds of historic structures. This process aids researchers in capturing precise geometries, surface textures, and structural intricacies that are crucial for restoration and preservation endeavors. Research has shown that the analysis and processing of point cloud data can accurately determine the physical and visual boundaries of structures [
7,
8]. Researchers have explored the integration of point cloud technology with 2D imagery to extract 3D information. This exploration involved the examination of four free and open-source software applications. The evaluation of these tools focused on their ability to generate point clouds and perform photogrammetric workflows, offering new insights and tools for the development and processing of point cloud data [
9]. Additionally, the application of laser scanning and BIM technologies has significantly impacted as-built modeling, information management, and the overall performance of construction projects. The researchers examined the advantages of incorporating BIM technology into real projects by conducting a case study on a building that did not utilize this technology [
10]. Moreover, laser scanning techniques and photogrammetry-based radiometric measurements have been employed to obtain precise building geometries. In addition, BIM has been established to oversee forthcoming restoration projects effectively [
11,
12]. Scientists suggested a method utilizing a 3D laser scanner and an algorithm for processing point cloud data to assess tunnel deformation. This technique involves the process of merging several point clouds and accurately aligning the point cloud data from different periods. The study’s findings offer crucial data for assessing the deformation performance of tunnels [
13].
GPS employs satellite signals to offer accurate geolocation data, allowing researchers to record the positions and movements of ancient structures precisely. This data is essential for conducting site surveys, generating maps, and tracking changes over time due to environmental or human factors. One approach involves the use of uncrewed ground vehicles (UGVs) equipped with sensors such as laser distance sensors, accelerometers, gyroscopes, and GPS sensors to develop classifiers for monitoring and quantifying pavement construction progress [
14,
15]. A separate investigation was carried out to assess the precision of elevation measurements by comparing ground-based and aerial photogrammetry with Real Time Kinematic Global Positioning System (RTK-GPS) [
16]. This method improves the precision of point cloud data, which is essential for examining topography, discontinuities, and other characteristics in surveyed regions [
17]. Additionally, researchers combined Social Vulnerability Index (SVI) data with GPS tracks from young individuals to explore the relationship between streetscape diversity and the time spent on active transportation (AT) [
18,
19]. The study revealed a significant correlation between streetscape diversity and the duration of active transportation, suggesting that a broader variety of streetscapes promotes higher levels of physical activity in young individuals. A study conducted in Austria focused on residential research and aimed to create a knowledge base and cadastre of adobe architecture in the Weinfeldt region. This outcome was accomplished by employing mobile technology to leverage and integrate the specific local and historical knowledge of the residents [
20].
BIM integrates architectural, structural, and engineering data to generate a unified 3D model. This model allows researchers to simulate and analyze ancient buildings’ physical and functional aspects. As a result, it facilitates accurate planning and visualization of conservation interventions [
21,
22]. Research has shown that BIM substantially affects the management of building projects by improving efficiency, precision, and overall project outcomes. Research has primarily focused on the benefits of BIM in managing building projects, highlighting improvements in data management, collaboration, and decision-making processes [
23]. BIM enables the efficient coordination of different project elements by integrating detailed building information, leading to improved resource allocation and shorter project timelines [
24]. Furthermore, researchers have investigated the use of BIM to preserve cultural heritage. These studies have focused on how BIM can effectively capture and depict architectural elements in 3D geometric models while maintaining accuracy [
25]. The results suggest that BIM can effectively aid in preserving and restoring cultural heritage monuments by offering detailed and accurate 3D models. Moreover, research on virtual modeling and reconstruction of architectural and historic buildings has highlighted the essential graphical and semantic data required to evaluate the conservation status of these structures [
26,
27]. Researchers have employed point clouds, historical records, and bibliographic data to develop parametric libraries within Heritage Building Information Modeling (HBIM) [
28,
29]. This method facilitates the comprehensive recording and conservation of historical structures, guaranteeing the precise capture and organization of all pertinent data for future restoration endeavors.
GIS integrates spatial data with attribute information to enable the mapping and analysis of the environmental and cultural context of ancient buildings. This integration allows for a better understanding of spatial relationships and historical significance, aiding in making informed preservation decisions. A GIS-MCDM approach has been employed in sustainable urban planning to assess spatial appropriateness in difficult situations like deserts. This approach incorporates various variables to evaluate and direct urban development [
30,
31]. GIS has also enhanced public parcel management by developing tools and platforms that provide online access to both qualitative and quantitative data. Open Access Web GIS platforms allow for the access and evaluation of entire management procedures and records, which improves transparency and efficiency [
32]. GIS technology has been applied to develop algorithms that automate the generation of real-time, personalized walking indexes, crucial for urban mobility. These algorithms utilize tailored comfort criteria derived from real-time data to optimize walking routes for urban populations [
33,
34]. GIS modeling approaches have been employed in analyzing commuting and residential placement decisions to investigate how environmental factors and amenities influence commuting behavior. These studies have shown that these elements substantially impact the decision-making process when it comes to choosing where to live and work. These findings offer valuable insights into the factors influencing residential choices [
35,
36]. In addition, GIS has been used to measure the social vulnerability and related risks of metropolitan regions. Composite metrics within a GIS framework have been used to detect and delineate geographical variability, providing policymakers and urban stakeholders with critical insights. This information is essential for developing focused and efficient programs to tackle urban difficulties [
37,
38].
This research explores preservation techniques for old buildings using advanced technologies like 3D laser scanning, GPS, BIM, and GIS. The case study focuses on two representative wooden structures, the Guanyin Pavilion and Tangwang Palace, located in Dahei Mountain. Through the use of 3D laser scanning and point cloud registration, we accomplished precise modeling and tilt monitoring of the Guanyin Pavilion. Additionally, by utilizing BIM and GIS technologies, we developed comprehensive records and dynamic data management for the architectural elements of Tangwang Palace. This included information on the architectural structure, historical development, existing issues, and maintenance planning. These approaches provide a viable solution for preserving cultural heritage by addressing issues like the lack of dynamic data integration and low modeling accuracy, challenges that traditional methods fail to adequately resolve. This study aims to demonstrate the effectiveness of current technologies in preserving old buildings, with a specific focus on the case studies of Guanyin Pavilion and Tangwang Palace (
Figure 1).
4. Discussion
4.1. Application of 3D Laser Scanning and Point Cloud Registration Technology in Guanyin Pavilion
This study employed the Trimble X7 3D laser scanner for high-precision modeling and tilt monitoring of Guanyin Pavilion. Through multi-station scanning and point cloud registration, we achieved high-precision modeling of the pavilion’s overall structure, with errors controlled within ±1 mm. Data indicates that among the 92 scanning stations, the introduction of absolute coordinates for planar targets in overall coordinate transformation significantly reduced stitching errors in the point cloud data. Using the ellipse fitting method to monitor the tilt direction and angle of the Tongtian Column, we found an average tilt angle of 0.4635°, with a maximum of 0.7892° and a minimum of 0.2115°. In distance measurements, the Trimble X7 demonstrated repeatability of 0.0052367 m at 7.99 m, 0.0143128 m at 25.57 m, and 0.0157100 m at 40.86 m, indicating high measurement accuracy. During point cloud preprocessing, noise points were effectively reduced. In model construction, sliced point cloud data was imported into Autodesk Revit to establish a 3D information model of Guanyin Pavilion. Comparison results indicated that the absolute error between the 3D model and the point cloud data was within 10 mm, meeting engineering requirements.
In this study, 3D laser scanning demonstrated distinct advantages over other technologies. It achieves millimeter-level accuracy, far exceeding that of alternative methods, and can capture comprehensive 3D data of a building in a single scan, thus avoiding the data omissions commonly associated with traditional techniques. While traditional hand measurements are commonly used for simple structures, their accuracy is often compromised by human error. In contrast, 3D laser scanning not only captures detailed geometric shapes but also facilitates seamless data integration and dynamic monitoring through multi-station scanning and point cloud registration, enabling the timely detection and precise analysis of structural changes—capabilities that traditional methods struggle to offer. Moreover, 3D laser scanning is more efficient than other methods, allowing for the rapid completion of complex structural measurements while reducing time and labor costs. These advantages make 3D laser scanning particularly effective in the preservation of complex buildings, ensuring the structural accuracy and safety of the Guanyin Pavilion.
4.2. Dynamic Data Management of Tangwang Palace
In studying Tangwang Palace, we used GIS technology to reconstruct the maintenance history for 1974, 1982, and 2000. Detailed records and visual displays via the GIS platform provided a comprehensive understanding of the protection status and maintenance history of the building complex. For instance, the GIS platform allowed us to view maintenance work from different years on a map, revealing the restoration content and methods of each stage. Additionally, we integrated BIM technology to thoroughly record and manage the geometric shapes and attribute information of the buildings, including architectural forms, historical evolution, existing deterioration, and maintenance design. For example, the BIM system detailed the weathering of square tiles and their corresponding treatment measures. BIM technology allowed us to accurately record the names, categories, deterioration phenomena, and treatment measures of each square tile, displaying them visually and ensuring data integrity and ease of management.
In the maintenance of Tangwang Palace, the combination of BIM and GIS technologies represents the optimal approach, offering substantial advantages over traditional methods. GIS provides macro-level spatial management, enabling a visual representation of the historical evolution and maintenance status of the entire complex. In contrast, traditional methods typically offer only static maps or textual records, which fail to capture the architecture’s complexity. BIM, meanwhile, focuses on component-level details, meticulously documenting and monitoring the geometric shapes and attributes of each architectural element. This level of detail far exceeds that of traditional hand measurements or 2D drawings, which are not only time-consuming but also struggle to maintain data consistency and accuracy. By integrating BIM and GIS, we achieved a comprehensive understanding of both the overall condition of Tangwang Palace and its components, facilitating the development of more precise maintenance strategies. This integrated dynamic data management system not only enhances management efficiency but also establishes a solid foundation for future preservation efforts, allowing us to more effectively address long-term maintenance challenges.
5. Conclusions
By integrating 3D laser scanning, GPS, BIM, and GIS technologies in Guanyin Pavilion and Tangwang Palace, this study yields the following key conclusions:
By utilizing high-precision 3D laser scanning and point cloud registration technology, the overall structural model of Guanyin Pavilion was controlled within an error range of ±1 mm. Tilt monitoring data showed that the average tilt angle of the Tongtian Column was 0.4635°, with a maximum of 0.7892° and a minimum of 0.2115°. Additionally, point cloud data analysis revealed that the relative error in key structures such as columns and beams was within ±10 mm. Based on this data, it can be concluded that despite years of environmental exposure, Guanyin Pavilion remains structurally stable. However, minor tilting and dimensional changes in certain parts require regular monitoring and maintenance.
On the GIS platform, the building elements of Tangwang Palace were meticulously documented, and the maintenance history of 1974, 1982, and 2000 reconstructed. By examining this maintenance information, we found that certain building elements repeatedly exhibited issues and were repaired, indicating long-term structural weaknesses in these areas. The roof tiles, mentioned repeatedly in the maintenance records of 1974 and 2000, showed signs of loosening and detachment. Despite repairs during each maintenance cycle, the problem persisted, suggesting potential design or material deficiencies in the roof structure. Records show that the wooden beams experienced corrosion and breakage in multiple maintenance cycles. Particularly in the 1982 and 2000 repairs, the restoration of wooden beams was a significant focus, indicating that the beams are highly susceptible to environmental influences and require special attention to protective measures. Wall cracks were noted in the maintenance records of 1974 and 1982, primarily on the building’s south wall. Despite multiple fillings and reinforcements, the cracks persisted, potentially due to foundation settlement or material aging. BIM excels in targeted management by accurately documenting and tracking individual building components, including comprehensive analyses of deterioration patterns and the effectiveness of specific restoration measures. When integrated, BIM and GIS combine spatial data with detailed architectural information, providing a comprehensive and dynamic tool for heritage conservation. This integration enhances decision-making accuracy regarding maintenance priorities and resource allocation by leveraging GIS’s spatial visualization and BIM’s component-level data management.
Despite achieving some results, this study has certain limitations: the unique nature of the study object may limit the applicability of the findings to other types of ancient buildings. The complexity of Guanyin Pavilion’s structure and its unique historical background required specialized methods and technologies that may not be easily transferable to simpler wooden buildings or those with different historical contexts. Future research should focus on adapting these advanced methods and technologies to be more universally applicable, especially for buildings with varying structural complexities. Developing more cost-effective data collection and processing methods, such as portable, low-cost 3D scanning devices and simplified software, could make these technologies more accessible to a wider range of sites. Additionally, integrating emerging technologies like artificial intelligence and machine learning could enhance the adaptability and efficiency of these methods, promoting the sustainable protection and utilization of a broader spectrum of ancient wooden structures.