Placing a minimum number of guards on a given watchman route in a polygonal domain is called the {\em minimum vision points problem}. We prove that finding the minimum number of vision points on a shortest watchman route in a simple polygon is APX-Hard. We then extend the proof to the class of rectilinear polygons having at most three dent orientations.

翻译：在多边形域中将最低人数的警卫安置在特定守望员路线上称为 ~ em 最小视点问题 。 我们证明在简单多边形中最短的守望员路线上找到最低的视线点是 APX- Hard 。 然后,我们将证据推广到最多有三个缩进方向的直线多边形。