BIDIRECTIONAL VISIBILITY

The percentage of the cross-sectional area of two objects (e.g., vehic les, hikers. or animals) that can be seen from each of their locations in a forested area is generally not the same. There is a directionali ty to the visibility between them. This is due to the relative positio ns and sizes of the vegetation and other view-blocking features betwee n the objects. An analytical technique has been developed to help unde rstand bidirectional visibility. Its use entails the construction of a visibility diagram containing the basic visibility information betwee n observers in a given setting. An example is presented showing the us e of the visibility diagram to determine visibility between two moving observers in a forested environment. The diagram is also used to dete rmine the differences in the percentage each observer has of the other 's visible cross-sectional area (bidirectional visibility). A discussi on of the application of the technique in the planning or development of new facilities, as well as in forest and wildlife management, is pr ovided.