5. Now let's again build two cubes using the existing planes as one side of each. This creates two new shade points 1 and 2 which cast shadow points Is and 2s.

The two new top shade lines again cast shadows parallel to themselves, thus forming two new sets of parallel, horizontal lines, each of which converges to its own vanishing point on the horizon.

6. Notice that each cube has a total of only two vertical shade lines. The other verticals that had been shade lines in previous steps are now "buried" in shade, i.e., are no longer boundary lines between light and shade; and therefore do not cast shadows. Only their shade points (* ) remain to cast shadow points (*8).

7. In all examples so far the sun has been in front of the observer, and therefore the vanishing point of the parallel light rays has been in fact the sun itself.

What vanishing point is used for the rays when the sun is behind the observer (top view below)! The theory is exactly the same. In perspective (right) the inclined parallel rays converge to a point, and, as before, this point is located on the vertical vanishing line that passes through the vanishing point of the pencils' shadows (since rays and shadows lie on parallel planes).

5WAOOW5' VAN. POINT

8. But two important differences do exist: 1.) This vanishing point is not the sun itself but simply a vanishing point for a set of inclined parallel lines. 2.) It is always below the horizon line. (If above, it would mean the sun is in front of and visible to the observer.)

The side views below, picturing the observer pointing to vanishing points, should explain why this is so.

UôHT RAY5 VAN. POINT

sun from in front /

[92] The Following Application Sketches All Have Shadows Cast By Parallel Light Rays (Sunlight)

Oblique To The Observer's Face (And To Picture Plane)

Therefore, the principles developed on the previous two pages will be evident. Note that when the vanishing point for light rays is close to the horizon the sun is low in the sky and the shadows are long. As the vanishing point increases in distance from the horizon — either above or below — the sun rises higher and the shadows become shorter. / /

Note: Arrowed lines are light rays used to locate important shadow points. Double-arrowed lines are shadow directions of uprights on ground plane. Dotted lines are temporary guide lines required to locate shadows.

The key to drawing the shadow of an inclined object (above) is locating the shadow of a point such as 1. This is done by constructing an upright (i.e., dropping a vertical) from point 1 to ground point 2 (located on ground-line B-C, which goes to right vanishing point and is directly below the oblique pole A-B.) Then, if we cast the shadow of the upright 1-2 (first along the ground and then up the wall) we can fix point Is. Thereafter, by extending a line from A thru Is and by connecting B with the ground intersection point of this line, we arrive at the correct shadow directions.

Under the Swings, by Robert Vickrey. Collection of Dr. and Mrs. John M. Shuey, Detroit. Courtesy of Midtown Galleries, New York

Ice Glare, by Charles Burchfield. Collection of Whitney Museum of American Art, New York

Under the Swings, by Robert Vickrey. Collection of Dr. and Mrs. John M. Shuey, Detroit. Courtesy of Midtown Galleries, New York

Ice Glare, by Charles Burchfield. Collection of Whitney Museum of American Art, New York

A light bulb hangs above a table at the point shown in top view. The diverging light rays must cast shadows along the dotted lines. In perspective, these same shadow lines are found by drawing the same diverging lines from the same table point (asterisk) through the same pencil points. These lines, naturally, are not light rays, for the actual source of light is somewhere above the table. To determine the exact lengths of the shadows along them, actual rays are drawn (from the light source) through erasers.

RULE: A local point source radiates diverging light rays which locate exact shadow points. But the shadow direction of upright lines on a plane is determined by lines diverging from the point on the plane that is directly below the light source.

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### Responses

• MARK BAIL
How to locate the vanishing point of light?
5 years ago
• Amerigo
5 years ago
• Nils
How to draw shadows for isometric drawing?
4 years ago
• luam berhane
How to create cast shadow techniques in prospective?
4 years ago
• Luis
How to draw shadows top view building?
4 years ago
• oran
How to draw shadows in one point perspective?
4 years ago
• LAMORAC
How to draw two point perspective interior?
4 years ago
• melanie
How to draw shadow of a building?
4 years ago
• wallace
How to draw shadow in perspective images?
4 years ago
• Cheryl
How to show shadow in perspective?
4 years ago
• LORI