Fine information extraction of 3D building seismic damage based on unmanned aerial vehicle oblique images

The three-dimensional image generated by the unmanned aerial vehicle oblique photography technology can better display the details of seismic damage on the side and top of buildings. However, it is difficult to directly extract the seismic damage information based on the three-dimensional image due to the high latitude characteristics of the image, and the two-dimensional texture image transformed by reducing the dimension often leads to the incompleteness and fragmentation of the seismic damage information of buildings. To solve these problems, this paper takes the 2017 Jiuzhaigou M_S7.0 earthquake as an example, and proposes a method for scattering the three-dimensional model, separating texture image from triangulated irregular network, and directly obtaining the complete side texture image after the Jiuzhaigou earthquake. Then, the optimal texture image is selected by using the tile coordinate range of pyramid model, the naming rules of tile and the spatial position of building monomer. After the optimal segmentation scale of building exterior wall in texture image is determined by using weighted mean variance method, this paper adopts the object-oriented method to extract the information of building exterior wall and wall skin shedding. Finally, through the analysis of earthquake damage characteristics of these buildings, the damage level of building monomer is determined. The results show that the method successfully obtains the complete side seismic damage texture images of buildings, and extracts the information of the external wall, crack and wall peeling area based on the texture image to determine the medium and serious damage levels of the building monomer.