When working within a three-dimensional model for applications such as personnel or camera placements, or for example, determining a Line-of-Sight for target acquisition or laser sighting in weapons delivery, a planner must verify that there is a clear Line-of-Sight from a specific position or target to any other point within the area of operation. This information is important to determine flight parameters for aircraft in target acquisition or planning or determine blind spots in ground operations for camera or personnel placement, for example.
Traditional two-dimensional maps cannot provide this information because the heights of relative objects is an unknown quantity. Additionally, placing a camera within a three-dimensional scene at a selected point does not provide this information because a camera cannot always be accurately placed and camera imaging does not provide intuitive confirmation across large distances.
A true, three-dimensional (3D) virtual environment requires the generation of an accurate Line-of-Sight (LOS) volume based upon a specific point referred to as the focus. By definition, a Line-of-Sight volume, when integrated into a three-dimensional environment, will give a user the ability to determine instantly a clear Line-of-Sight to the designated focus by observing the camera placement inside or outside of the rendered Line-of-Sight volume. A rendering of a Line-of-Sight volume will also allow its use outside of traditional data visualization where three-dimensional data analysis is performed.
Currently, there are no known applications that produce true three-dimensional Line-of-Sight volumes. U.S. Pat. No. 6,411,298 to Goto et al., the disclosure which is hereby incorporated by reference in its entirety, discloses a method and apparatus that determines visual points and direction of Line-of-Sight in three-dimensional image construction. The system and apparatus of Goto et al. primarily determines a visual point and direction for a Line-of-Sight in a three-dimensional image construction used for imaging blood vessels and similar pathways. A viewpoint is set on an intersection of two arbitrary multi-planar reconstruction (MPR) images. A Line-of-Sight is displayed on a plane, including either one of the two MPR images. The geometric positional relationship of the two MPR images, their intersection and viewpoint, and Line-of-Sight, are designated with a positional input device, for example, a computer mouse, to enable rearrangement of the geometric positional relationship. By outputting an instruction to move the position and direction of a marker on the plane, including a first sectional image, and updating the viewpoint and Line-of-Sight, it is possible to set an estimated viewpoint and Line-of-Sight. Goto et al. is limited, however, in its applicability for generating an accurate Line-of-Sight volume based upon a specific point as a focus in a three-dimensional environment.
In another application for generating a Line-of-Sight, ESRI Company of Redlands, Calif., has developed a software program that produces multi-colored lines radiating out from ground based points along a terrain surface. These multi-colored lines indicate those areas that have Line-of-Sight to a point, but only along a surface. This program, however, does not have sufficient resolution for some end-use applications. This program is perhaps advantageous from a point out across the scene, but it is not sufficiently adequate for scenarios that determine Line-of-Sight capabilities for antenna placement, blind spots across a radar sweep, or similar applications requiring a Line-of-Sight volume for a specified point in a three-dimensional model.