Optics principles. For example, the Ames room, Hering, Müller-Lyer, Orbison, Ponzo, Sander, and Wundt illusions all rely on the suggestion of the appearance of distance by using converging and diverging lines, in the same way that parallel light rays (or indeed any set of parallel lines) appear to converge at a vanishing point at infinity in two-dimensionally rendered images with artistic perspective. This suggestion is also responsible for the famous moon illusion where the moon, despite having essentially the same angular size, appears much larger near the horizon than it does at zenith. This illusion so confounded Ptolemy that he incorrectly
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,