Research On 3D Building Model Simplified Method In Mobile Terminal

Buildings as the most important part model in the digital city,the fineness and complexity of the building model are directly related to the quality and efficiency of the application of the 3D city model.However,due to the growth of graphics hardware processing capabilities lags far behind the ever-increasing 3D data size,complex geometric models are difficult to be quickly drawn,which greatly limits its wide application in resource-constrained devices.In addition,the existing model automatically simplifies the algorithm mostly for single building models,retaining the main features to reduce unnecessary redundancy.For common building groups,this type of approach tends to overlook the features of neighboring buildings and the interconnections with surrounding features,resulting in the loss of simplified model body features.Therefore,based on the complexity of the model structure,we choose to simplify the detailed features of the algorithm to optimize the model,to maximize the retention of the main structure of the model to eliminate the redundant features,in order to meet the level of human visual perception.In the field of the computer graphics and digital city geographic information system as an important research direction.Currently,the PC terminal can efficiently display a fine three-dimensional building model.However,due to the limited resources of mobile terminals,the same level of detailed models cannot be directly displayed on the mobile terminal.Compared with PC terminal devices,mobile terminals such as mobile phones and tablets require a suitable compact model in their visualization.The application of three-dimensional architectural models on mobile devices usually adopts the following three measures:(1)low-precision geometric description of buildings;(2)high-precision geometric description of landmark buildings;and low accuracy geometry description of other buildings;(3)In the map,landmark buildings are described with high-precision geometry description and texture maps,and the remaining buildings are described in two dimensions.Through research and analysis,we know that the current research focuses on reducing the amount of data on the building model and optimizing the real-time rendering,in order to achieve the purpose of balancing the accuracy of the model and mobile device performance.Considering the characteristics of mobile terminal modeling,the multi-level model is built to facilitate the rational invocation of the model,which can minimize the transmission of the model and improve the rendering speed.In this paper,we study on the basis of original model,combined with the characteristics of mobile terminal platform,improve the classic simplified algorithm,put forward a kind of can automatically generate to keep building group of structural features of model simplification algorithm.According to complex building floor plan subdivision model,get the subunit parts,on the basis of the subunits of roof structure continues to divide,to determine the top is flat roof or inclined roof structure,using top-down method of projection to reconstruct building model,finally to jointly form a simplified complete all parts of the model.In this paper,the quality of geometric model is evaluated from the model vertex number,triangle mesh,memory size,corresponding data compression ratio and appearance similarity.Compared with other classical algorithms,this paper simplifies the compression ratio of the method,and the specific compression ratio changes with the complexity of the model.The experimental results show that the proposed simplified method,in keeping the buildings the main outline of the characteristics,on the basis of making full use of the geometry of roof structure,get less redundancy wall body part,reconstruct the hierarchy model of mobile client demand.