Research On The Scheme Design Of 3D Fine Modeling Technology For Towering Ancient Buildings

China ’s ancient architecture has a long history,unique shape,fine design cumbersome,rich and colorful decoration,is the crystallization of ancient wisdom.Ancient buildings are vulnerable to the continuous destruction of natural environment and human activities.The digital protection of ancient buildings is imminent.Among them,the use of photogrammetry technology for fine three-dimensional reconstruction of ancient buildings is an efficient digital method.However,due to the influence of UAV flight height,camera lens angle and ground object occlusion,it is still difficult to capture image data in some areas.It is difficult to ensure the overlap between adjacent images by manually controlling the UAV or the camera.The ground camera shooting technology is single,and there is no specific shooting method in the completely occluded area.The operator ’s lack of photography experience is likely to cause photography ’ loopholes ’ and low modeling accuracy.Finally,UAV images and camera images rely on connection point matching modeling time-consuming and laborious,and will bring errors.Starting from the problem of how to construct a refined model of towering ancient buildings,this paper uses a variety of photogrammetry technologies to conduct in-depth research on how to efficiently and automatically collect high-resolution image data and construct a refined three-dimensional model.The specific research work is as follows :(1)A technical scheme suitable for aerial photography of towering ancient buildings was designed.The characteristics of the five-direction imitation ground route and the circular vertical multi-ring route are analyzed.Aiming at the towering ancient buildings,the corresponding routes are designed and the high-resolution images are collected.The data acquisition,modeling efficiency and model quality of the fixed height flight and the prismatic vertical multi-ring route are compared and analyzed.The results show that the ground-like route can greatly improve the modeling accuracy and the model accuracy of the five-way ground-like route is higher than that of the surrounding ground-like route.The circular vertical multi-loop route can shoot objects from multiple angles,increase the intersection angle between images,make the aerial triangulation calculation easier to pass,reduce the number of images,shorten the modeling time,improve the efficiency,and greatly reduce the cost of modeling.The model produced is more precise,more accurate,and the overall effect is better.(2)The technical scheme of flight modeling in the near-ground area of towering ancient buildings is proposed.Analyze the characteristics of the elevation route,design the linear elevation route,and use the UAV to automatically collect high-resolution images of the nearground area.Calculate the appropriate transition route parameters and design the transition route to collect the transition image,and improve the success rate of aerial triangulation calculation of near-ground image and ground-like image under the premise of reducing the number of images.And compared with the model effect constructed by the common manual addition connection point auxiliary matching method.The results show that the UAV can efficiently and automatically obtain the near-ground image data according to the facade route.The facade transition route can improve the success rate of the five-way ground-like tilt image and the linear facade image together with the aerial three-matching,and the production model is more fine,more accurate,and the overall effect is better.(3)The acquisition and modeling technology scheme of indoor area image data is designed.For the interior areas of ancient buildings that are difficult for drones to photograph,the camera station layout scheme is designed according to the coarse model.The camera shooting method of first overall and then detail,first intersection and then integrity,and the combination of intersection and integrity is used for shooting.Finally,the image is controlled and encrypted by the control point and the coordinate transformation is used to integrate the aerial photography data to construct a refined three-dimensional model of air-ground integration and evaluate the accuracy.The results show that the three-dimensional model constructed by the fusion is more complete in geometry,richer in texture,clearer in color and more obvious in detail features by using the camera to capture the internal area of the ancient building.The mean square error of 3D model is 0.0271 m in plane and 0.0247 m in elevation,which meets the accuracy requirement of Level I achievement in ’ 3D geographic information model data product specification ’,and can provide good data basis and technical reference for3 D modeling of towering ancient buildings.