Method for scanning reflectivity information to generate tunnel lining image by virtue of three-dimensional laser

The invention discloses a method for scanning reflectivity information to generate a tunnel lining image by virtue of a three-dimensional laser. The method comprises the following steps: scanning to obtain each lining ring point cloud data of a tunnel by virtue of the three-dimensional laser; extracting the point cloud data of each lining ring, carrying out translation rotation around the axis center position of each lining ring, and then sequentially arranging in a standard cylinder according to the mileage; unfolding the inner wall point cloud data of the lining ring into a plane through isometric tangent projection; and finally carrying out interpolation by virtue of the projected point cloud reflectivity information to generate the tunnel lining image. The tunnel lining image generated by the method is relatively high in mileage accuracy, main feature size measurement accuracy and image resolution; the position, size, area, type and the like of tunnel disease information can be extracted from the image information after manual or computer visual interpretation; in addition, the method can be used as a novel technique for tunnel maintenance; and the quantitative analysis capability of tunnel inspection can be greatly improved.