Research On Modeling Technology Of High-precision 3D Real Scene Model In Urban Built-up Area

With the rapid development of social economy and the acceleration of the process of urbanization,the requirements for informatization and intelligent city construction have become more and more prominent,and the simulation of urban form has gradually developed from two-dimensional plane to three-dimensional.As the basic data for smart city management and urban dynamic analysis,people's demand for 3D real-scence models is increasing,and requirements for high precision,automation and low cost are also required for model construction.In recent years,the emergence of drone oblique photogrammetry technology has promoted the development of large-scale real-scene model construction,and provided effective technical support for the construction of high-precision three-dimensional real-scene models of urban built-up areas.This paper uses Nanjing University of Information Science and Technology as the experimental area to explore the key technologies for the construction of high-precision 3D real scene models of urban built-up areas.The main research results are as follows:1)Exploring the layout of image control points.Taking into account the shape of the urban built-up area and the features of the ground features,explore the optimal number and location of image control points,in order to complete the established model accuracy control under the condition of the least image control points.the result shows:The distribution of image control points in urban built-up areas should adopt the method of"edge plus center".By placing 18 image control points per square kilometer,the plane accuracy of the model can be controlled to be better than 5 cm.After that,as the number of image control points continues to increase,the accuracy of the model tends to increase.The number of image control points and the plane accuracy of the model satisfy the formula:y=5×10-6x2-0.0007x+0.0635,and the fitting degree R2 is 0.9752.2)Multi-source data fusion modeling.A fine model of the ChangWang tower was constructed using the fusion of oblique and close images.Compared with the modeling results of a single oblique image,the multi-source and multi-scale image fusion modeling can significantly alleviate the distortion of the structure of the ChangWang tower model and completely restore the texture details of the tower near the ground.The model quality has improved significantly.3)Refined model modification.Based on DP-Modeler and Photoshop professional software,complete the work of model suspended matter deletion,water surface cavity repair,building structure deviation and road surface modification,etc.Compared with the original model,it can be seen that under the condition that the accuracy of the model remains unchanged,the refined modification of the model by means of human-computer interaction can significantly improve the quality of the model details.4)Image control post-processing modeling.Because it is difficult to arrange image control points in urban built-up areas and the point coordinate collection is subject to many interference factors,in order to overcome the impact of image control points on the efficiency of the field work,this paper carries out image control post-processing model construction and accuracy analysis.The results show that the three-dimensional model established by image-free control has local morphological distortions such as mismatches and faults in the overlapping areas of the route.Research has found that the direct cause of this phenomenon is image overlap.By cleaning up redundant overlapping image interference,it can eliminate the above phenomenon;Based on the model established without phase control,adding appropriate image control points to re-establish the 3D model,the plane accuracy of the new model can reach the conventional modeling accuracy.Figure[57]table[14]reference[75]...