Virtual port modeling method based on dynamic fluid field data

To achieve the digital upgradation of ports, a virtual port modeling method based on the dynamic flow field data was proposed. The geometric feature of a port was reconstructed by the three-dimensional (3D) reconstruction model with the aerial image data of unmanned aerial vehicle (UAV) oblique photography, and a high-precision 3D model was established. The simplified model of the edge collapse algorithm based on the quadric error metric was introduced to prevent low rendering efficiency caused by the data overflow. The high time consuming step in the numerical calculation of Euler method was analyzed. A neural network model was built to learn the evolution feature of the flow field. The calculation of the projection term was accelerated to produce the dynamic flow field data that were used to drive the dynamic rendering of water flow. The smoothed particle hydrodynamics (SPH) method was employed to reflect the interactions of water flow with ships and land. In this way, not only was the real-time performance of rendering ensured, but also the realistic effect of rendering was improved. Research results show that the 3D reconstruction model of the reconstructed port has 3 320 937 vertices, and the rendering frequency of the reconstructed grid model is 78.7 Hz in Meshlab. After almost 90.0% of the vertices are removed from the model via model simplification, the number of vertices reduces to 332 836, and the rendering frequency enhances to 108.7 Hz. The geometric errors of the model are smaller than 2.0% after simplification. In a 256×256 flow field grid, the average update interval is roughly 17 ms for the water flow velocity field obtained by the grid fluid calculation method accelerated by a neural network, and the average simulation precision is 88.6%. When the flow field data and 3D port model were driven by an open scene graph (OSG) engine, the average rendering frequency can reach 50.5 Hz. In conclusion, the proposed method can effectively solve the key problems in high-precision real-time rendering to achieve the dynamic balance between simulation precision and rendering efficiency. It enables high-precision virtual port modeling and real-time dynamic simulation without great precision loss. 1 tab, 11 figs, 30 refs.