The purpose of this note is to give a simple proof for a necessary and sufficient condition for visibility paths in simple polygons. A visibility path is a curve such that every point inside a simple polygon is visible from at least one point on the path. This result is essential for finding the shortest watchman route inside a simple polygon specially when the route is restricted to curved paths.

翻译：本说明的目的是为简单多边形的可见性路径提供一个必要和足够条件的简单证明。可见性路径是一个曲线,使至少从路径上的一个点可以看到简单多边形内的每一点。这一结果对于在简单多边形内找到最短的监视者路径至关重要,特别是当该路径被限制在曲线路径上时。