Simulation Study Of CT Projections For Cultural Relics Based On UG Model

In recent years,the digitization of cultural relics has become a research hotspot.Traditional digital modeling of cultural relics usually uses 3D laser scanning equipment to acquire point cloud data on the surface of cultural relics,which can’t model the internal structure of cultural relics effectively.Industrial CT is an advanced imaging technology that can acquire the internal structural information of objects under non-destructive conditions,and provides an effective means for digital modeling of internal structure of cultural relics.The first step in digital modeling of cultural relics is to acquire CT projection data.In fact,the high cost of scanning is due to the high cost of industrial CT equipment,and the random movement or contact with cultural relics is likely to cause secondary damage to cultural relics.Therefore,it is necessary to obtain the CT projection data of the cultural relics by simulation,and then carry out the "scanning" of the cultural relics model in various ways,so as to provide ideal supporting data for the image reconstruction and 3D digital modeling research of the subsequent cultural relics model.The research work in this thesis mainly includes:(1)Realization of CT projection simulation of UG cultural relic model.For the single material cultural relic model established by UG,the entity identification of the model is obtained at first when the simulation is performed,and then the UG/Open API function is used to intersect the ray with the object,and the path length of the ray passing through the object is determined according to the intersection sequence.Combine the model material name to find the corresponding attenuation coefficient in the database and calculate the projection data.On this basis,for multi-material cultural relics model,first traverse the model,get the entity objects of each material and save them in the collection.In the projection simulation,each material object in the set is simulated by a single material model,and the results are synthesized to obtain the projection data of the final multi-material model.The experimental results indicate that the proposed projection simulation method can obtain ideal projection data for the UG cultural relics model.(2)Multi-core parallel computing based on projection simulation algorithm is proposed.Aiming at the slow calculation speed of CT projection simulation of UG model,a multi-core parallel computing method is proposed: Firstly,the parallelism of the projection simulation algorithm is analyzed,the circular tasks in the algorithm are decomposed by the task parallel mode,which is divided equally into each processor core to achieve load balancing.Using Windows API function to create multiple threads and start the process in the threads,thus realize multi-core parallel computing of projection simulation.The experimental results show that the proposed method achieves a nearly linear acceleration ratio while ensuring the projection accuracy.(3)A cultural relic CT projection simulation system based on UG model is realized.According to the CT simulation requirements of the cultural relics model,the CT projection simulation system is designed and implemented according to the proposed simulation algorithm.The MFC framework is used to organize the functions,which integrates single material projection simulation based on UG model,multi-material projection simulation,ray source discrete simulation and multi-core parallel computing of projection simulation and supports the reconstruction of slice images by projection data,etc.The simulation system is demonstrated by examples,which provides a convenient virtual experiment platform for the follow-up study of digital modeling of cultural relics.