Research On Spectral Scattering Characteristics Of Targets With Brdf And 3D Reconstruction Theory

It is the theoretical basis for achieving optical detection,tracking and recognition of the target to obtain the spectral scattering characteristics of the target Based on the three-dimensional reconstruction theory,a non-contact method to quickly reconstructing the three-dimensional size model of the target is used in this paper,which is combined with the target spectral BRDF to study the spectral scattering characteristics of the target.The main research contents and results are as follows:(1)A seven-pararneter BRDF model with bimodal characteristics is proposed,which overcomes the inability of most previous models to accurately fit data with double-peak characteristics.The seven-parameter BRDF model can not only fit single-peak BRDF data but also can fit bimodal BRDF data,which has a wide range of applications.Based on the composition of Martian soil,the Martian simulated soil is prepared,and the spectral BRDF of Martian simulated soil are measured,which are used to fit by the seven-parameter BRDF model.The spectral BRDF of earth sand samples with different roughness are compared and analyzed,and the spectral BRDF of the same roughness Mars simulated soil and earth sand sample are also compared and analyzed.(2)The principle of 3D reconstruction based on target multi-angle images is studied deeply.Then the 3D reconstruction algorithm and point cloud stitching algorithm process are introduced.Finally,the three-dimensional reconstruction software of Context Capture is used to reconstruct the three-dimensional model of sand bag,tank and fighter,which can be forming a three-dimensional point cloud with the surface texture of the actual object.(3)Based on the 3D point cloud of the target obtained by the 3D reconstruction,the target surface and surface bins are generated by Delaunay triangulation.Combined with the spectral BRDF model of the target sample,the spectral scattering characteristics of sand bag,tank and fighter are studied and analyzed.The spatial distribution of the spectral scattering brightness of sand bag,tank and fighter are calculated,and the spectral scattering characteristics of the Lambertian and Non-Lambertian surface sand bag,tank and fighter are compared and analyzed.The research results show that the spectral scattering characteristics are greatly affected by the spatial geometry of the target object,the surface material characteristics and the detection irradiation angle in the detection of the visible light band.In general,Non-Lambertian targets spectral scattering characteristics have strong directivity,and Lambertian targets are easier to detect.