[ CLIII]
Sun Behind the Picture Throwing Shadow on an Inclined Plane
| Fig. 275. |
The vanishing point of the shadows on an inclined plane is on a vertical dropped from the luminary to a point (F) on a level with the vanishing point (P) of that inclined plane. Thus P is the vanishing point of the inclined plane K. Draw horizontal PF to meet fL (the line drawn from the luminary to the horizon). Then F will be the vanishing point of the shadows on the inclined plane. To find the shadow of M draw lines from F through the
base eg to cd. From luminary L draw lines through ab, also to cd, where they will meet those drawn from F. Draw CD, which determines the length of the shadow egcd.
[ CLIV]
The Sun in Front of the Picture
| Fig. 277. |
When the sun is in front of the picture we have exactly the opposite effect to that we have just been studying. The shadows, instead of coming towards us, are retreating from us, and the objects throwing them are in full light, consequently we have to reverse our treatment. Let us suppose the sun to be placed