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

Cast Shadow Value

  • 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

Cast Shadow Edges

  • 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 object lightly
  • draw the line of termination and fill in the shadow area with a No. 3 value


  • 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


  • use angle sighting to construct the shape of the cast shadow


  • construct the shadow by drawing two ovals and connecting them with a line

The Assignment

  • 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

Polystyrene sphere
Polystyrene sphere
Paper cube
Paper cube
Paper cylinder
Paper cylinder