Oblique Image Based Automatic Aerotriangulation and Its Application in 3D City Model Reconstruction

In this paper, we proposed an automatic aerotriangulation method based on SWDC-5 oblique images. First of all, we designed an improved viewpoint-invariant matching method for oblique images based on the perspective transformation. Secondly, in order to reduce the amount of unknown adjustment parameters (overmuch unknown adjustment parameter may weaken the instability of adjustment solution), we offered a new bundle adjustment model for oblique images which took the relative attitude parameters of cameras into account, and also gave the application scope of the model. Experiments conducted on the typical SWDC-5 oblique images demonstrated that when the relative attitude of cameras (on same camera station) are stable and their cameras exposure are limited within a short time delay, the aero-triangulation accuracy of our method is high, the unit weight error is 0.46 pixels and the average residual of image points is 0.27 pixels. Thirdly, we applied the results of aero-triangulation to PMVS (patch-based multi-view stereo matching) algorithm to gain the dense point-cloud of the experimental city, used screened Poisson reconstruction algorithm to get its 3D mesh, and reconstruct its 3D surface with 3D texture algorithm. Experiments showed that the accuracy of the aero triangulation met the requirements of applications, and the obtained 3D city model had a natural, real texture, all this proved that the idea of automatic reconstruction of 3D city model is feasible and made a good reference for the large-scale 3D city model reconstruction.