The Art & Science of Drawing: Week 7: Day 3: The Cast Shadow

Day 3 of Week 7 of The Art & Science of Drawing is about the cast shadows - the shadow produced by an object on nearby surfaces.

Shadow elements we’ll study:

shape (present even for diffused shadows)
value (in a 5-value scale, the shadow is represented with values No. 5, No. 4 and No. 3)
edges (some are crisp and easy to define, but others are diffuse)

Cast Shadow Shape

length of the shadow depends on the height of the light source
- the lower the light source, the longer the shadow

occlusion shadow
- darkest part of the shadow
- light blocked completely
- this is were you should use the No. 5 value
the farther you get from the occlusion region, the lighter the shadow
usually, the shadow should go from a No. 5 (the occlusion region) to a No. 4

hard edge in the occlusion shadow area
the farther you get from the object, the more diffuse the edge becomes
penumbra
- the diffuse edge of the shadow, away from the object
- it depends on the light source and how far from the object it is
- it is more pronounced when using a point light source (like a lamp) than when using parallel light source (like the sun)

draw the shape of the shadow
- for a sphere, determine the axis, the length and the width of the cast shadow ellipse
- to determine the length, you can use an angle reading
you can mark on the sphere where the shadow intersects the sphere
once you get the right shape, start adding value
- start with lighter value than you’ll need in the end
- use darker values (No. 5) in the occlusion are and lighter values (No. 4)
do not use hard shadow away from the object

light & draw a sphere, a cylinder & a cube
draw the basic form, the line of termination & a light value wash on the shadow side
draw the cast shadow as in the demonstration
- draw the shape
- add value
- pay close attention to the edges, especially the diffused ones