Abstract: With the very rapid development of computer performance and simulation technology, very realistic visual system with multi-channel can be completed completely using personal computer and high speed graphics accelerator. Visual system with multi-channel can provide 120x〜360 degree horizontal field of view using 3〜11 channels, and each channel consists of a projector projecting the computer generated image to it's screen part. In marine simulator three different kind of screens are used widely; they are flat screen, polygonal screen and cylindrical screen etc. Different screen has different advantages and disadvantages. The author will analyze the precision, advantages and disadvantages of visual systems employed in marine simulators using different screens. Another key technologies of multi-channel visual system in marine simulator, such as multi-channel visual system configuration multi-channel synchronization, dynamic setting of viewing direction and the position of eye-point for each channel and Dead-Reckoning algorithm will be introduced in details.

　

 With the rapid development of computer performance, various simulation systems are playing more and more important roles in training, scientific research and engineering demonstration area etc. The effects of simulation system applied to training are determined by the realism of operating environment which has become a very important factor to evaluate a simulation system. The realism of environment is mainly decided by visual system. There are several ways to display image in simulation systems ^[1]: Head Mounted Display (HMD), stereo projection wall(such as CAVE system), semi-sphere displaying system using single projector(such as Vision Station or Vision Dome series made by Elumens Inc.), wide field of view visual system with multi-channel etc. HMD device can provide strong feeling of immersion, but it is always applied to system operated by single person. For systems usually operated by a work team such as bridge simulator, wide field of view system with multi-channel is adopted. Wide field of view system with multi-channel can be classified to plane system, cylindrical system and spherical system according to it's projecting screen used. Special graphics workstation such as Onyx2 of SGI or personal computer with high performance graphics accelerator can be used to generate images of visual system with multi-channel. But it is too expensive. Recently, the speed of polygon processing and pixel filling rate of high performance graphics cards have increased very fast^[2], they can be utilized in visual system with multi-channel for generating very realistic images. Some key technologies of multi-channel visual system in marine simulator, such as multi-channel visual system configuration, multi-channel synchronization, dynamically setting of viewing direction and the position of eye-point for each channel and Dead-Reckoning algorithm will be introduced in details.

　

 Computers as the same number of channels are used in multi-channel visual system each computer generates it's own part of image independently, then the image is projected to the screen of it's own part and put together to create the scene with wide angle field of view. Typical multi-channel visual systems used in marine simulator are shown in Fig.1 and Fig.2, Fig.3 shows the configuration of marine simulator with multi-channel visual system.

　

　

　

　

2.1 Flat Screen System

　

 The price of flat screen system is quite cheaper, because there is no need for the projector used in flat screen system to have non- linear geometry correction ability. Flat screen system is suitable to be applied to the auxiliary own-ship visual system. Usually, the number of channels used in multi-channel flat screen system is three, and the horizontal field angle of view is less then 120 degrees. Multi-channel flat screen system can be configured as two patterns: Equal angle of field of view pattern and Equal screen size pattern.