Helong Shen

Simulation of shallow-water waves in coastal region for marine simulator

This paper presents a new method for simulating shallow-water waves for the marine simulator. Firstly, a sequence of sea surface height fields is achieved by solving 2D Boussinesq type equations. These height fields can exhibit the combined effect of the most shallow-water waves in the coastal region, such as shoaling, refraction, diffraction, reflection and non-linear wave-wave interaction, etc. Secondly, these height fields are synthesized to a new unlimited long sequence by rearranging their order according to their similarity. Finally, the height fields are used as vertex textures sampled by a view-dependent sea surface grid in the new order. Experimental results show that the simulated shallow-water waves have realistic effect with fast rendering speed. It is suitable for the applications of real-time simulation, the marine simulator especially.

Real-time dynamic simulation of 3D cloud for marine search and rescue simulator

As the main scenery of sky, the effect of 3D cloud influences the fidelity of visual system and the immersion effect of simulator. In this paper, based on the work of Y. Dobashi and T. Nishita, small region Cellular Automaton is generated and more realistic cloud simulation is improved. The experimental results show that the visual system of simulator can run in real-time and has a relatively higher refresh rate after changeable 3D cloud being applied.

Sea Surface Simulation in Large Coastal Region for Maritime Simulators

A novel method for simulating large-scale, nearshore sea surface is presented. The whole simulating process can be divided into two phases: pre-computing phase and real-time computing phase. In pre-computing phase, wave parameter distribution of a simulation area is worked out using the SWAN (Simulating WAves Nearshore) model on a coarse grid. In real-time computing phase, a small height field surrounding the viewpoint is generated using the Fast Fourier Transformation (FFT) based method every frame. The wave parameters used in the FFT-based method are dynamically changed according to viewpoint’s projective position on the coarse grid. Then, the height field is saved as a vertex texture, which can be tiled in horizontal directions seamlessly. At last, the vertex texture is sampled by a sector sea surface, which is viewpoint-dependent and has Level Of Detail (LOD) effect. Several shading trips are used to generate optical effects of sea surface, such as reflection, refraction etc. Experimental results show this method can be applied to simulating large-scale sea surface in real-time with realistic effect. It is especially suitable for the application in maritime simulators.

Real-time Simulation of Large Area Nearshore Wave for Marine Simulator

A new method for nearshore wave simulating is introduced. Firstly, parabolic mild-slope equations are set up according to the simulation area and input waves. After solving the equations, the integral wave parameters such as the root mean square wave height, the peak wave period and the mean wave direction can be calculated. Instantaneous surface elevations can also be obtained from the model. Then, the integral wave parameters and an instantaneous surface elevation are composed into a float texture. Finally, a viewpoint-dependent sea surface is rendered using this texture as wave parameters. Experimental results show that this method can be applied to simulate large area nearshore wave in real-time with realistic effect. It is suitable for the application of real-time simulation, particularly for marine simulator.

Modeling and simulation of the trawl in fishing simulator

The aim of the present study is to develop a numerical calculation method to accomplish dynamic simulation of the fishing nets in fishing simulator. Fishing nets were modeled as a group of lumped mass points interconnected with springs that have no mass under the uniform flow motion. Nonlinear dynamic equations of fishing nets were solved with the precise integration method. The position and velocity can be obtained by solving the net model. The comparison of the results of this study against associated experiment revealed the numerical method of nets model is reliable, while the real-time of simulation was ensured. This study shows that our method is valid for the simulation of fishing nets.

Dead Reckoning Based Rendering of 3D Cloud for Shiphandling Simulator

Light interaction considering scattering and absorbing is implemented with some simplicity physically. Dead reckoning based calculation is used during the implementation. After the 3D cloud being integrated using Cellular Automata clouding modeling method, experimental results show that it has realistic effect with fast rendering speed on a common PC. The method in this paper is very suitable for the visual scene system in Shiphandling Simulator.

Notice of Retraction The Model Research on Route Planning and Route Monitoring Simulation

In order to avoid the sudden events and deal with the safety problems in time in practical navigation, the simulation models of route planning and route monitoring are put forward, the theory and the algorithm of indicator kirge are applied in the research of route planning so that the water depth of anyplace is computed by fitting curved surface of sea-bottom terrain, the way of human-machine interaction is taken to amend planned sea route to realize auto-deciding of feasibility according to ECDIS information, and the algorithm of route monitoring is improved by avoiding the imprecision caused by screen coordinate making use of coordinate conversion. Meanwhile, all these methods are correct and credible, and are validated through working on high quality navigation simulator developed by Dalian Maritime University.

Rendering of 3D Cloud for Marine Search and Rescue Simulator in Real-time

Based on the previous work of modeling dynamic 3D cloud using Cellular Automata, this paper renders realistic 3D cloud for Marine Search and Rescue Simulator visual system in real-time. Physically based light interaction is implemented by Open Scene Graph with a common PC. Light scattering and absorbing is considered. After the 3D cloud integrated into the visual scene, experimental results show that it has realistic effect with fast rendering speed. It is suitable for the applications of real-time simulation, Marine Search and Rescue Simulator especially.