ResearchArticle An Alternative Method for Long-Term Monitoring of Thai Historic Pagodas Based on Terrestrial Laser Scanning Data: ACaseStudyofWatKracheeinAyutthaya Peerasit Mahasuwanchai , Chainarong Athisakul ,PhasuSairuamyat , Weerachart Tangchirapat , Sutat Leelataviwat ,andSomchaiChucheepsakul DepartmentofCivilEngineering,FacultyofEngineering,KingMongkut’sUniversityofTechnologyonburi, Bangkok10140,ailand Correspondence should be addressed to Chainarong Athisakul; chainarong.ath@kmutt.ac.th Received 14 February 2021; Revised 6 May 2021; Accepted 18 May 2021; Published 3 June 2021 Academic Editor: Alessio Cascardi Copyright © 2021 Peerasit Mahasuwanchai et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. is article presents an alternative method for the long-term monitoring of heritage pagodas in ailand. In this method, terrestrial laser scanning (TLS) is used in combination with permanent survey markers. e Wat (temple) Krachee in the Ayutthaya Province of ailand was chosen as a case study. is temple has several fantastic elements, including an inverted bell- shaped pagoda, two intertwined trees growing within it, and a chamber inside the pagoda. e preservation team working on the pagoda encountered a challenging problem and faced a decision to trim or not to trim the tree since it has a long-term effect on the pagoda’s structural stability. A high-accuracy terrestrial laser scanner was used to collect three-dimensional point cloud data. Permanent survey markers were constructed in 2018 to be used in long-term monitoring. e 3D surveying of the temple and the monitoring of the pagoda were carried out in five sessions during a period ending in 2020. A point cloud data analysis was performed to obtain the current dimensions, a displacement analysis, and the pagoda leaning angle. e results revealed that the terrestrial laser scanner is a high-performance piece of equipment offering efficient evaluation and long-term monitoring. However, in this study, permanent survey markers were also required as a benchmark for constraining each monitoring session. e 3D point cloud models could be matched with the assumption model elements to evaluate the damaged shape and to determine the original form. e significant elements of an inverted bell-shaped pagoda were investigated. Trimming the tree was found to cause the leaning angle of the pagoda to decrease. An equation was developed for predicting the leaning angle of the Wat Krachee pagoda for preservation and restoration planning in the future. From the results of this study, it is recommended that periodic monitoring should continue in order to preserve ai pagodas in their original forms. 1.Introduction e cultural heritage sites of ailand are considered an invaluable resource for the nation. Over time, the heritage sites have been inevitably affected by natural disasters and damage by humans. For this reason, assessment and monitoring of the historical structures are essential to prevent future damage. In traditional surveying methods, the surveyors or engineers must collect information by hand, which is a time-consuming process with low precision. It also requires a surveyor’s specific expertise to investigate the anomalies of this historic structure. Today, the most effective instrument for surveying and monitoring is the terrestrial laser scanner (TLS). It has been used for the massive col- lection of three-dimensional data for structures in their current condition. An advantage of this technology is the relatively short time and its high accuracy in digitizing real- world objects [1]. is information can be processed and developed for the assessment and risk management of historic buildings [2–4]. Previous research has reported the application of the terrestrial laser scanner in engineering, architecture, and various other fields, such as prototyping Hindawi Advances in Civil Engineering Volume 2021, Article ID 5587046, 17 pages https://doi.org/10.1155/2021/5587046