Research On Multi-resolution Color 3D Model Fusion Method

In the 3D digital protection of archaeological sites,a high resolution site agent model is often used to establish a high resolution site agent,using a fixed wing unmanned aerial vehicle to establish a low resolution terrain model of 1 square kilometers around its surrounding unmanned aerial vehicles.The high resolution 3D model has high resolution and fine texture.It can meet users' need for 3D model size measurement,volume calculation and HD display.The low resolution model has the advantages of low cost and wide coverage,and it can produce large area 3D models economically and efficiently.In order to satisfy the user in the same 3D model,the site agent model can be measured with high precision,and the surrounding terrain and geomorphology information can be understood,and the cost of model production can be taken into account.A multi-resolution color 3D model fusion method is proposed in this paper.The main ideas are as follows: first,the 3D model of the fusion is preprocessed,the part of the site agent is dug from the low resolution terrain model,and the high resolution site agent model built by the rotor unmanned aerial vehicle is embedded.Then the fusion buffer is established in the gap between the two models,and the construction is built in the fusion buffer zone.The Delaunay triangulation with constrained boundary is used as a "bridge" to connect two 3D models and reattach the texture to the reconstructed triangular mesh to achieve the integration of the two 3D models.This method can effectively solve the time-consuming and hard work of the artificial fusion model,which leads to the confusion of the spatial position of the model and the hardening of the texture.It improves the efficiency of the fusion of multi-resolution color 3D models and ensures the quality of the 3D model after the fusion.The main processes involved are as follows: 1.3D models with different resolutions were built using different kinds of UAVs.Two models were stacked and clipped,and the fusion buffer was established.In the fusion buffer,the vertices are interpolated by dividing the rule grid.2.In the 3D model fusion buffer,we construct the Delaunay triangulation network with constraint boundaries.Taking the internal and external boundary of the buffer as the constraint condition,the "double helix" Delaunay triangulation method based on improved convex closure contraction method is adopted to restrain the direction of restructured grid,and the new Delaunay triangulation network is generated only in the buffer zone,and it will not change the three-dimensional model grid structure outside the boundary of the buffer zone.3.The texture mapping method based on harmonic mapping method is adopted to complete the coordinate transformation from 3D model to 2D texture pixel.According to the rule of harmonic mapping,we remap texture for a textured grid model.4.Taking a site group in Yanqing District of Beijing Province as an example,we use the algorithm to carry out multi-resolution color 3D model data fusion experiment.The result is compared with the results of manual fusion of 3D models using existing commercial software.The experimental results show that the method proposed in this paper achieves the fusion of multi-resolution color 3D models,and the fusion can achieve the smooth boundary and texture splicing of natural effects,and retain most of the texture and grid data of the original model,reflect the minimal intervention to the original model,and greatly improve the efficiency of the model fusion.