Research On Key Technologies Of Real-time Rendering And Interaction Of Ocean Scenes

The ocean is the cradle of life on the earth,and it is an important space for human survival and development.The virtual ocean is widely used in many fields such as scientific research,ocean engineering,military training,tourism and cultural communication.Researchers have been working to find models that are authentic and computationally inexpensive.We focus on four important components of virtual ocean scenes: wave rendering,surface detail simulation,surface optical effect rendering and human-computer interaction.Our aim is achieving a balance of realism,real time and interactivity.Firstly,long wave spectrums are frequently used to model ocean waves in the field of computer graphics,which cause the lack of short wave effects.We propose a real time rendering method based on a unified direction spectrum for long and short waves.Based on the comparison and analysis of existing wave spectrums,we learn from the omnidirectional spectrum in the field of ocean remote sensing,then we introduce and improve the unified direction spectrum for long and short waves.The improved spectrum covers the wind speed,wind direction,wind fetch and water depth parameters,and the parameters can be adjusted and controlled.The method effectively makes up for the shortcomings of the existing methods.Secondly,aiming at the real-time simulation of ocean surface details,we introduce the voxelization method to classify the objects floating on the ocean,and carry out the force analysis and calculation on the basis of voxels.Using the principle of physical rigid body dynamics,we reproduce the real motion states of arbitrarily shaped objects on the ocean surface including the concave polyhedron.Based on the principle of volume conservation,the generation and propagation of interactive waves are assumed to be two independent processes.We construct an interactive wave generation formula which determines the position and initial amplitude of the interactive wave.The formula also reflects the properties of liquid free surface waves.To simulate the propagation and diffusion process of interactive wave in real time,we put forward a two-dimensional wave equation with a viscous drag coefficient,and the Verlet integral method is introduced to solve the equation.We simplify the vortex construction method and skillfully use the vertex warping method to quickly generate vortex effects in ocean scenes using shaders.Thirdly,in order to reproduce the dynamic and complex optical effects of the ocean surface,we build up a comprehensive ocean lighting rendering model which is driven by time and space.In this model,we apply a skysphere method which is convenient to position the celestial objects and to set up the light scattering model.To show the real movement of celestial spheres,we establish a simplified astronomical model to compute the position of every single celestial sphere in the scene.Via analyzing the characteristics of the clear sky,we realize the atmospheric scattering effect based on the color gradient texture and the simplified scattering equation.We set up an ocean BRDF illumination model to compute the light reflected from the sun and the sky dome.Considering the light scattering in the ocean,we construct a subsurface scattering model of the ocean,and approximate the diffusion solution due to a dipole source method.Furthermore,aginst the monotony of human-computer interaction in virtual ocean scenes,we propose a somatosensory interactive expansion system for virtual ocean scenes.Introducing a depth camera as the somatosensory interaction device,we design a simple and efficient gesture semantics set,and establish the correspondence between human skeleton motion and various elements in the virtual ocean scene,which realize the somatosensory control of ocean elements such as waves,lights and warships.The white-wave trail of the warship is rapidly and realistically simulated by the using of particle systems.We simplify the take-off process of the carrier-based aircraft,and extend the warship's traveling somatosensory control to the flying control of the carrier-based aircraft.In addition,we apply single-user and multi-user team/combat modes to provide interactive experiences with high degrees of freedom.Finally,we design and implement a variety of verification,optimization and evaluation experiments.The experimental results show that the realism,real time and interactivity of ocean scenes are effectively improved.