Research On Processing Method Of Triangular Mesh With Structural Information Constrained

With its flexible photography method,oblique aerial photography can quickly and multi-anglely acquire more ground information,so that the 3D reconstruction of large scenes with textures can be completed with a single oblique aerial image source.Compared with other 3D reconstruction methods,such as 3D laser scanning and manual modeling,oblique3 D scene reconstruction has the characteristics of high data collection efficiency,large scene adaptation,and low cost.Therefore,it is favored by relevant scholars and industries,and become one of the research hotspots in the field of photogrammetry and computer vision.The mesh is the skeleton of the model,and the quality of the mesh plays a vital role in the optimization and texture mapping effect and efficiency.Unfortunately,there are still many problems from the data itself to the mesh construction algorithm,such as data redundancy,missing point cloud data in special scenes,and non-manifold geometry.These problems have seriously affected the development of 3D reconstruction of oblique images and restricted its potential development.In response to these problems,this thesis proposes a triangular mesh model processing method with structural information constraints.Based on the principle of protecting the original structural characteristics of the triangular mesh,the triangular mesh obtained by the mesh construction is processed to reduce data redundancy,simplify data expression,and repair model holes,So as to obtain an accurate,complete,and high-quality manifold triangle mesh with a high degree of summary of the object.The main research contents and contributions of this thesis are as follows:1)This thesis focuses on the method of triangular mesh processing in 3D reconstruction of oblique images,discusses its advantages and disadvantages,and problems that need to be solved at the current stage.It introduces the current status,basic theory and key technologies of triangular mesh processing.Analyzes the core nature and existing problems of existing related algorithms.2)Aiming at the problem that the classic mesh simplification based on quadratic error metric appears abnormal triangle shape and abnormal topology structure after the mesh simplification,this thesis proposes a mesh simplification method constrained by structural information.When calculating the cost of edge collapse,the algorithm fully considers the change of triangle structure information,redefines the quadratic error matrix of boundary points,and adds the self-intersection detection result to the decision condition of edge collapse.In this thesis,the algorithm obtains the characteristics of triangulated mesh with structure preservation and strong topology,and solves the problem of the mesh structure in the simplified algorithm use the classic quadratic error metric.3)The VCG hole detection method not only fails to identify boundary holes,but the treatment of non-manifold holes can cause abnormal topologies during hole repair.In this regard,this thesis proposes a non-manifold hole detection method based on intersection judgment.In this method,the non-manifold holes are detected in zones,so that the zones are repaired without interfering with each other.This method can accurately identify the model boundary holes,and the detected non-manifold holes will not produce abnormal topological structure in the subsequent repair process.4)In view of the VCG hole repair method,the transition between the new and old triangles is not smooth,and the structural features of the hole area are missing.This thesis proposes a structure-aware hole repair method.The algorithm achieves a smooth transition between new and old triangles by fitting an implicit surface constraint to add new triangles.The proxy plane is extracted to obtain the perception of the model structure,so as to achieve the repair of the structural characteristics of the hole area.In order to prevent too few constraint points from controlling the construction of large-area implicit surfaces,this thesis adopts a step-by-step method to repair the holes.The method achieves a smooth transition between the new and old triangular faces,and at the same time has a good effect on the restoration of the structural characteristics of the hole area.