Oldal 103 [103]
OCR
REFLEXIONS IN RIPPLED WATER :7 for any given receding line is the point where the line from the eye parallel to it meets the picture plane. It will be found that the projections on to the picture plane of lines in the ground plane radiating from a point vertically below the eye are vertical lines. This is illustrated in Fig. 19. The spectator is here supposed to be stationed above the water and to be looking directly at the bridge to the right of the diagram. E marks the position of his eye or “station point,” A B C D represents his “ picture plane,” with the projection of the bridge as it appears to him, o being the " centre of vision,” Eo the “direction of vision,” and H the horizon line. EX is a perpendicular drawn from E to meet the “ground plane” (surface of the water) in X. L,, L,, etc. are lamps on the near side of the bridge, and F,, F,, etc., are points on the surface of the water vertically beneath these lamps. The streaks of light on the surface of the water caused by these lamps will appear to one looking from E to lie along the straight lines X F,, X F,, etc., which radiate from the point X immediately beneath his eye. But the projection of these radiating lines on to his picture plane will be vertical, and therefore parallel, lines. Let the lines XF,, XF,, etc., cut the base of the picture plane (or “sround line”) in the points g;, g, etc. From these points draw perpendiculars g, 4,, g2 Aa, etc., to meet the horizon line of the picture in 4,, A, etc. Then the lines EX and 4,3;, being vertical, are parallel to each other; and since the plane containing E and the horizon is parallel to the ground plane, these lines, EX and 4,g,, are also equal. Therefore EX, is parallel to Xg,; and therefore, by the well-known law of perspective, 4, is the vanishing point for the line XF,. Similarly it can be shown that 4, is the vanishing point for XF,, ha for XF,, and so on. Thus in the picture the streaks of light are represented by the vertical lines /, £1, /2 £a/s 23 etc. In “Modern Painters”* Ruskin makes reference to a picture by Claude, in which the artist has fallen into an error ‘ Vol. I, Part II, Sec. V, Chap. I, § 17.
