Research On Fine Modeling And Protection Of Grotto Temples Based On Multi-Source Data Fusion Technology

Cultural relics inherit historical culture and highlight the civilization of the time,which is the tangible witness of the continuous development of the Chinese nation in the long river of history.As an unrepeatable artistic heritage in the development of human society,grotto temple has many values,and the protection of cultural relics is very important.However,due to the limitations of the natural environment,human activities and protection ability,numerous cultural relics are facing the crisis of accelerated extinction,and the protection of cultural relics is imminent.Owing to the characteristics of different environments,different sizes and complex geometric structures of grotto temples,the protection of cultural relics is very difficult.The protection of cultural relics of grotto temples in China is not systematic and is in its infancy.It mainly develops from passive protection to preventive protection,and the digitization of cultural relics has developed into the most influential means of prophylactic protection.With the rapid development of digital technology,photogrammetry technology,three-dimensional laser scanning technology,geological exploration technology and computer vision are widely used in the cultural relics protection industry,providing an effective means for the digital protection and long-term preservation of cultural relics.Taking the No.1 cave of Tuoshan Grottoes as an example,this thesis obtains the point cloud and image data of the grottoes through the station scanner,hand-held fine scanner and digital camera,and proposes a fine modeling method based on the station scanning point cloud as the overall control network and the fusion of hand-held fine scanning point cloud and dense matching point cloud;Through the classical ICP algorithm and rotation angle constrained ICP algorithm,the registration accuracy in multi-source point cloud data is analyzed.After the point cloud registration,Poisson algorithm is used to reconstruct the point cloud;the texture mapping method of thin plate spline function and its shortcomings is introduced.Each control point is given different weights,so that each control point can complete the texture mapping of complex model under different elastic coefficient constraints;After the completion of digitalization of cultural relics,non-destructive detection technologies such as X-ray fluorescence,X-ray diffraction and rebound detection are used to detect and analyze the diseases of the grottoes,so as to provide a set of practical protection schemes for the preventive protection of the grottoes.The main conclusions are as following:（1）Based on multi-source data,through the rotation angle constrained ICP registration algorithm and the texture mapping method of weighted thin plate spline function,the fine modeling of grotto temple cultural relics in special space environment can be realized on the premise of ensuring accuracy and efficiency.The geometric structure of the fusion modeling model is more complete,the details are retained more fully,and the texture is free of dislocation and distortion,which can effectively ensure the objectivity and authenticity of the cultural relics model.（2）The texture mapping method of weighted thin plate spline function has a better effect on the texture mapping of complex models.Through the texture mapping experiment of thin plate spline function and weighted thin plate spline function,the results show that the method of adding control point weight is more accurate for the mapping result of complex model,solves the phenomena of texture dislocation and knurling in complex feature positions,and effectively eliminates the local mismatch error caused by rigid registration method.（3）According to the analysis of grotto test results,Tuoshan No.1 grotto is mainly faced with water erosion and damage.It is therefore proposed building grotto eaves outside the grottoes and uses hydraulic lime to block rock cracks to solve the threat of water damage.Tuoshan Cave 1 is mainly composed of microcrystalline dolomite,calcite and microcrystalline quartz.The rock mass is uniform,the compressive strength is high,the weathering resistance is ineffective,it is easy to be dissolved in water,and there are abundant cracks around the grottoes,which are seriously eroded by water.