Ren Hongxiang

Real-time Shadow Rendering in Scene System of Marine Simulator

In the large-scale scene system based on scene management software, an efficient method was presented to render shadow with shadow volume algorithm. Approaches were discussed to convert scene model from openflight file to 3ds file. The data used to determine silhouette edge was obtained by accessing the simplest LOD of model A new method that reduced silhouette edge by removing redundant internal edge was provided. A new strategy of shadow rendering was presented: depending on models position, shadows were rendered with z-pass algorithm utilizing CPU or z-fail algorithm within vertex shader. The method and strategy presented in this paper can be integrated directly into the large-scale scene system based on scene management software. The effect of shadow rendering meets the real-time and reality requirements of scene system.

Real-time rendering of ocean in marine simulator

The scientific, rapid and realistic rendering of ocean is always a difficult problem in marine simulator. A spectrum method of ocean simulation was developed in the paper. The fast Fourier transform based on GPU was used to generate the height map. A grid model of concentric circles was proposed to replace ocean surface geometry, and the height of grid vertex could be obtained through accessing the height map in vertex shader. Then the choppy waves was simulated and the repeating tiles of ocean was reduced. The reflection and refraction of ocean surface were rendered. The method developed in the paper has been successfully applied in the visual system of marine simulator.

Automatic Assessment Model for Sailing in Narrow Channel

Firstly, analyze the relevant IMO regulations about vessels proceeding along a narrow channel, then establish a evaluation index system combining with the theory of ship handling; secondly, establish membership functions by using the membership function evaluation method for every evaluation index; Thirdly, obtain the weights of evaluation indexes utilizing the expert evaluation method; At last, establish the evaluation procedure and develop the automatic evaluation model for vessels proceeding along a narrow channel by using C++ programming language. This system has been tested preliminarily with satisfied results.

Ship motion modeling and simulation in Ship Handling Simulator

For developed irregular waves, wave heights or wave amplitudes are gained using the wave spectrums. Based on the hypothesis of Froude-Krylov, ship shape is predigested box. Wave forces and moments to ship motion can be calculated. They are added in the motion mathematical models, and ship six degrees of freedom mathematical models are given. Using the fourth order Runge - Kutta integration method solves differential equations. The mathematical models are applied to Full Mission Ship Handling Simulator. Six degrees of freedom of the ship: the location, attitude and speed and acceleration are passed to the other modules in the navigation simulator, in order to achieve interaction between human and computer. As an example, a cargo ship that its displacement is ten thousand tons are simulated in three sea states, the time histories of motion are good and the viewing scene is very vivid. The results are shown that the mathematical models can meet the engineering demands.

The Marine Safety Simulation based Electronic Chart Display and Information System

Navigation safety has a huge impact on the world economy and our everyday lives. One navigation safety simulation model in ECDIS based on international standard format (S-57) is put forward, which is mainly involved in route plan and route monitoring. The universal kriging interpolation is used in the route planning and to compute the water depth of any place in the sea bottom. The man-machine conversation method is taken to amend planned route to obtain autodeciding of feasibility according to ECDIS information, and the route monitoring algorithm is improved by enhancing its precision caused by screen coordinate conversion. The DCQA (distance close quarters situation of approach) model and TCQA (time close quarters situation of approach) model are adopted to judge if the close quarters situation or the risk of collision between own ship and target ship is emerging. All these methods are proven to be reliable through the navigation simulator made by Dalian Maritime University which is certified by DNV to class A.