Vanishing point is below the horizon line, its vanishing lines angle up to the horizon line. If the object is above, they slope down. All vanishing lines end at the horizon line. 1. Projections of two sets of parallel lines lying in some plane appear to converge, i.e. the vanishing point associated with that pair, on a horizon line, or vanishing line formed by the intersection of the image plane with the plane parallel to and passing through the pinhole. Proof: Consider the ground plane , as which is, for the sake of simplicity, orthogonal to the image plane. Also, consider a
Point plotting |"x"| from the origin and along the positive direction if "x"≥0, and the other direction otherwise. In the same way one picks the point on the "y" axis corresponding to the number "y". The line parallel to the "y" axis going through the first point and the line parallel to the "x" axis going through the second point will intersect at precisely one point, which will be called the point with coordinates ("x", "y"). Point plotting Point plotting is an elementary mathematical skill required in analytic geometry. Invented by René Descartes and originally used to locate positions on military maps,