Terrain Visibility Algorithm Research And Design

The concept of Intervisibility has broad applications in all kinds of Simulation Systems. Intervisibility, in its basic form, is the task of determining if one simulated object can "see" another in the simulated environment. To answer that question it must be determined if the line segment in 3-space connecting the two objects intersects any polygons of the terrain database. The two objects are said to be intervisible when this line segment lies strictly above the terrain.Though simple in concept, intervisibility is crucially important to some types of simulations, such as Computer Generated Forces systems and sensor simulations. In a CGF system, because each intervisibility determination can be computationally expensive and many may be required, intervisibility determination is almost always the single most computationally expensive operation, potentially consuming so much of the system's computational resources that CGF entity behavior generation is negatively affected.In simulation systems, the digital terrain models can be described by a regular or irregular grid of discrete terrain elevation values. This paper studies point-to-point intervisibility algorithms on Regular Square Grid terrain model and Triangulated Irregular Network terrain model. Not only the intervisibility algorithms currently in use are analyzed and realized, but also improvements are done to them, and two fast intervisibility algorithms are designed. All algorithms are tested on real terrain data. The result indicates that the improvements and designs are effective. They can meet the need of different Simulation Systems. The achievements in this paper could be applied to develop all kinds of simulation systems.