Perspective (graphical) with one-point perspective. These parallel lines converge at the vanishing point. One-point perspective exists when the picture plane is parallel to two axes of a rectilinear (or Cartesian) scene – a scene which is composed entirely of linear elements that intersect only at right angles. If one axis is parallel with the picture plane, then all elements are either parallel to the picture plane (either horizontally or vertically) or perpendicular to it. All elements that are parallel to the picture plane are drawn as parallel lines. All elements that are perpendicular to the picture plane converge at a single point
Drawing the parallel lines forming a side converge at a second point along the horizon (which may be off the drawing paper.) This is a two-point perspective. Converging the vertical lines to a third point above or below the horizon then produces a three-point perspective. Depth can also be portrayed by several techniques in addition to the perspective approach above. Objects of similar size should appear ever smaller the further they are from the viewer. Thus the back wheel of a cart appears slightly smaller than the front wheel. Depth can be portrayed through the use of texture. As the texture