Convex hull algorithms is very simple. The leftmost vertex is on the convex hull and we denote it formula_6. The second point is assumed to be a candidate convex hull vertex as well. At each step one looks at three consecutive vertices of the polygon, with two first ones tentatively assigned to the growing convex hull and the third one is a new unprocessed vertex of the polygon, say, we denote this as formula_7. If the angle is convex, then formula_8 and the whole triple is shifted by one vertex along the polygon. If the resulting angle is concave, then the middle point
Parallel projection central or perspective projection, in which the rays pass through a fixed point called the "center" or "viewpoint", as this point is moved towards infinity. Put differently, a parallel projection corresponds to a perspective projection with an infinite focal length (the distance between the lens and the focal point in photography) or "zoom". In parallel projections, lines that are parallel in three-dimensional space remain parallel in the two-dimensional projected image. A perspective projection of an object is often considered more realistic than a parallel projection, since it more closely resembles human vision and photography. However, parallel projections are popular in