The integration of terrestrial laser scanning and terrestrial and unmanned aerial vehicle digital photogrammetry for the documentation of Chinese classical gardens -Â A case study of Huanxiu Shanzhuang, Suzhou, China

Chinese classical gardens, which contain various landscape elements and complicated spaces, are an important component of both gardens worldwide and culture heritage sites. However, there is a research gap regarding surveys and the digital documentation of Chinese classical gardens. In this study, we take one of the most famous and important Chinese classical gardens - Huanxiu Shanzhuang (HXSZ) in Suzhou, China - as an example and apply multiple techniques including terrestrial laser scanning (TLS) and terrestrial and unmanned aerial vehicle digital photogrammetry (TDP and UAVDP) to acquire comprehensive data of its diverse elements. These multi-source data were integrated on the basis of point clouds via two steps - fusing the TLS and UAVDP point clouds firstly and integrating the TDP point clouds with the already-merged TLS and UAVDP point clouds. Both these two integrations included coarse and fine registration. With the integrated point clouds of the garden, 3D models and 2D fine drawings of the landscape elements and the garden were constructed to document the study site and show its complicated characteristics. The purpose of this study is to: survey, measure and display the rich and complicated landscape elements and spatial characteristics of HXSZ, and make 3D models and digitally document for HXSZ. The high-accuracy 3D models and fine drawings obtained in this study are crucial for the cultural heritage preservation of HXSZ. Our multiple surveying methods, data processing of multi-source data and presentation and documentation of the data are not only useful for Chinese classical garden preservation, but also could be applied to other researches of cultural heritage sites that contain various elements and complicated space characteristics.