Search

The starting point of ancient architecture digitization and 3D reconstruction research is data acquisition. Thus, this paper mainly analyzes the processing of 3D laser scanning data and the construction accuracy of 3D reconstruction models of ancient buildings based on point cloud data. This paper discusses the basic theory of point cloud data and the preprocessing of point cloud data, including point cloud splicing, point cloud denoising, point cloud streamlining, point cloud segmentation, and other methods and applicability are discussed in detail. The boundary extraction algorithm based on RANSAC and the graph cut algorithm are utilized to obtain the main frame line of the building, and a proposed method for reconstruction based on multi-view projection is proposed. Classify laser point cloud samples from ancient buildings, calculate each wall color’s R, G, and B values, and obtain preliminary classifications of laser point cloud data categories. The RANSAC algorithm was used to extract the point cloud data plane extraction peak of the ancient tower building, combined with the three-dimensional modeling coordinate difference of the test points, to analyze the accuracy of the three-dimensional modeling technology of ancient buildings in this paper. The number of plane extraction points of the RANSAC algorithm is 9504, and the standard deviation is 0.0505, which is close to 0. The results are more accurate, and the extraction effect has a certain degree of superiority. The plane coordinate deviation of the reconstruction model of the ancient tower is mainly concentrated in the range of 0.10~0.40m, and the individual coordinate difference is more than 0.10m. The errors in the x -direction and y -direction are ±0.18m and ±0.23m, respectively, and it can be seen from the results of the error calculation that the three-dimensional reconstruction plan of the building proposed in this paper can complete the reconstruction of the three-dimensional model of the building with a high degree of accuracy.

Purpose: The aim of this study was to evaluate the role of a novel total meniscal implant in promoting meniscal regeneration and protecting articular cartilage in a rabbit model for 3 and 6 months. Methods: Thirty‐six New Zealand rabbits were selected and divided into poly(ɛ‐caprolactone) (PG‐Pg) scaffold group, meniscectomy group and sham group. In this study, it was investigated whether PG‐Pg scaffold can prevent articular cartilage degeneration and promote tissue degeneration, and its mechanical properties at 3 and 6 months after surgery were also explored. Result: The degree of articular cartilage degeneration was significantly lower in the PG‐Pg scaffold group than in the meniscectomy group. The number of chondrocytes increased in the PG‐Pg scaffold at 3 and 6 months, while a gradual increase in the mechanical properties of the PG‐Pg stent was observed from 6 months. Conclusion: The PG‐Pg scaffold slows down the degeneration of articular cartilage, promotes tissue regeneration and improves biomechanical properties after meniscectomy. This novel meniscus scaffold holds promise for enhancing surgical strategies and delivering superior long‐term results for individuals with severe meniscus tears. Level of Evidence: NA. [ABSTRACT FROM AUTHOR]

During the construction of underground engineering, the prediction of groundwater distribution and rock body permeability is essential for evaluating the safety of the project and guiding subsequent design and construction. This article proposes an objective function that solves an underdetermined inverse analysis problem based on the least-squares theory and regularization method and uses geostatistics theory and the variogram function to describe the spatial characteristics of the actual engineering system. It also establishes an optimization model of the analysis stratum seepage field and puts forward the method of using on-site test observation data to solve the stratum penetration coefficient. Relying on the foundation pit project of the Lingshanwei Station of Qingdao Metro, the on-site pumping and packer permeability test was conducted for different strata venues in the foundation pit, and the on-site water-head observation value was obtained. Physical detection of the influence area of foundation pit excavation confirms the correctness of the model from the region and verifies the accuracy of the model on the value through the on-site pumping test. Results show that the accuracy of the use of this objective function to solve the underdetermined inverse problem is above 85%, which proves the effectiveness of the method. The stratigraphic geological information obtained by the inverse analysis model provides an important basis for engineering design and security construction. [ABSTRACT FROM AUTHOR]