The Mathematic Method Related to Modeling Visible Range of Points in Mountainous Region

Using mathematics method,the visible range of points at a certain height in mountainous region was researched in this article.By calculating the tangent points between the visible cone of an observed point and the mountains'surface,the whole-visible cone-shaped surface of the point was constructed,then the contour of surface was computed at a given height.Afterward,contours of the whole-visible cone-shaped surfaces of many observed points were united.Finally,the whole contour of the points was smoothed,and the whole-visible area of the observed points was got.