Three-dimensional Modeling Of City Buildings Based On Oblique Photography And The Study Of Texture Mapping

With the application of urban planning,architectural landscape design,three-dimensional navigation and urban tourism,the "digital city" construction of "smart city" space carrier is rapidly promoted by real-time dynamic observation of the demand of real model,The construction of the "digital city" in the major cities is becoming more and more urgent,and the 3D model of digital city is gradually built into a rapid development stage.Three-dimensional urban model production from the traditional remote sensing images combined with topographic map production,the use of three-dimensional laser scanning data production,the use of airborne Lidar point cloud data to the use of aerial photography technology can not meet the current reconstruction of real three-dimensional model fast and efficient,The real request.The use of traditional modeling methods has many shortcomings such as long modeling period,low potential,low modeling cost,lack of geographic information,unreal texture,low model accuracy and so on.3D laser scanning technology can not solve the problem of texture data acquisition and Deal with the problem;airborne Lidar technology model is not accurate,the accuracy is relatively poor.However,in order to achieve the "wisdom of the city" construction,we must first achieve fast,efficient and accurate real three-dimensional modeling.Tilt photogrammetry technology is a new high-tech development in the field of international surveying and mapping remote sensing in recent years.It overturns the limitations that traditional aerial photography can only be taken from vertical angle.By carrying more than one sensor on the same flight platform,From the vertical,tilt and other different angles to collect images,the use of tilt imaging measurement technology to obtain the tilt image can quickly complete the city three-dimensional modeling,and provide a rich texture information for the model,a true reflection of the human eye vision of the city scene,For the construction of "digital city" to provide space and geographic information base.In the reconstruction of real 3D models,the two most important steps are to build three-dimensional building models and texture maps.Based on the emerging tilt photogrammetry technology,this paper describes the modeling method based on oblique photography technology.The advantage of obtaining the texture of the building based on the oblique image and the means of optimization are analyzed.On the basis of obtaining the white figure of the building,through the visibility analysis,the optimal texture of the corresponding ground area is selected according to the best angle method and the depth caching algorithm to deal with the fuzzy,automatic extraction and dense building of the urban building texture Texture of the occlusion of the problem.The main contents of this paper are as follows:(1)Contrast and analysis of several commonly used modeling methods,and their applicability is described,and then focused on the tilt imaging measurement technology based on the modeling method to solve the current modeling model of the existing modeling Long cycle,high cost of modeling,lack of geographic information,unreliable texture,low model accuracy,improve the quality and efficiency of modeling.(2)This paper describes the texture mapping principle,methods,process.This paper introduces the acquisition method,texture extraction principle and occlusion method of texture data source,such as the selection of texture data source,the calculation of mapping relation,texture extraction and texture masking.The paper introduces the method of texture data based on oblique image Texture mapping process.(3)In this paper,the M600 pro aerial vehicle is equipped with Riy-D2 camera to obtain the oblique image data of the study area.After the data preprocessing,the regional network joint adjustment,the aerial triangulation and the oblique image-dense matching to generate the DSM point cloud,TIN,Texture mapping and editing,etc.,to generate a real three-dimensional model of the study area.Finally,the accuracy of the model is evaluated by the 20 checkpoints that are evenly distributed in the study area.(4)In the study area,we choose the area where the texture is blurred and occluded,and the consistency of the reconstructed texture is realized by using the image uniform light and the processing to eliminate the blur.Through the visibility analysis,the optimal texture is selected by the object-based perspective method,and the heave judgment is combined with the depth caching algorithm.Implementation process to VC ++ and OpenGL for the development platform.Experiments show that the texture mapping process can solve the problem of texture blur and occlusion,and improve the authenticity and completeness of the 3D model after the above optimization.