Viewing angle : because of the way light passes through the liquid crystals in the display , lcds may appear to lose some brightness and image quality as you move to the side of the screen , or above or below it 3 .可视范围：可视范围简单的说，指的是在萤幕前画面可以看得清楚的范围。可视范围愈大，自然可以看得更轻松可视范围愈小，只要观看者观看位置，画面可能就会看不清楚了。
According to the installation of the camera on the hebut - i mobile robot , analyzing the stereo vision model of lateral camera in detail in this thesis . at the same time , common visible region and the model error of this model are studied deeply , further more , the error produced by the error of the correspondence is analyzed in detail 并按照hebut -型移动机器人视觉系统中摄像机的配置关系，详细分析了摄像机横向配置的立体视觉模型，对该模型的共同可视范围、模型误差进行了深入的研究，同时对由于摄像机的配准误差而产生的误差进行了分析。
The algorithm performs real - time calculation of the grade value that remote host relatives to the host based on the area the host can see in the virtual environment . according to the grade value , the system divides the entities into different grades and sends different grade ' s data adopting various standards in order to reduce the amount of communication data of the low - grade entities 该机制根据本机结点在虚拟环境中的可视范围，实时计算远程主机相对于本机的级别值，并按照该级别值将实体分为不同等级，采取不同的标准发送数据，以达到减少低级别值实体通信数据量的结果。
Shiphandling simulator is a device that can partly imitate the true environment at sea ， and is specially designed to satisfy marine education and trains and maritime research etc . one of its key techniques is to create the virtual environment at sea ， and the terrain is its important component . according to the needs of the real time visual display of the shiphandling simulator ， this paper analyses the requirements of the geometry precision of the important islands and background hills which are within the ships ' visible scope ， and brings forward the modeling methods of the hill ' s pileup and the hill ' s silhouette edges based on contour lines . it also presents the definition of error that the hill ' s silhouette edges graph has been given and the effective scope of application ， and firstly established the error criterion of terrain model that is built in shiphandling simulator . with these two kinds of method ， the size of data storage can be minimized greatly ， and the requirements of high update rate and geometry precision for the real time visual display of the shiphandling simulator can be satisfied 船舶操纵模拟器是一种能够部分模仿海上真实情况,专门为满足航海教育与培训、航海技术研究等目的而设计研制的装置，其核心技术之一是海上视景模拟，而地形地貌是海上视景中的重要组成部分.根据船舶操纵模拟器实时视景显示的需要，在分析航行船舶对可视范围内重要岛屿与背景山脉的几何精度要求的基础上，提出了基于等高线的山形堆积建模和山形轮廓建模方法，并给出了山形轮廓图形的误差定义、有效适用范围，以及船舶操纵模拟器中地形建模的误差准则，该方法生成图形的数据量较小，其图形更新速率与几何精度能达到船舶操纵模拟器实时视景显示的要求
