Light and Form

Key Terms:

• The Form Principle:
• analysis of nature in terms of geometric solids
• Modeling Factors
• each lighting setup has a different set of tonal steps from light to shadow
• Terminator
• area where the form transitions from light into shadow. It occurs where the light rays from the source are tangent to the edge of the form.
• also called the "bedbug line"
• Occlusion shadow
• points of contact that include the darkest parts of the shadow
• Core of the Shadow
• another dark part of the shadow just beyond the terminator
• only forms if the secondary source of light doesn't overlap too much with the main light
• Half light
• the darker halftone just before the line of the terminator divides the light from shadow

Grouping Planes

• It helps if you organize groups of planes that are roughly parallel. 
• Grouping planes makes it easier to sort things out
• Always try to state the form in terms of light and shadow

Texture at the Terminator

• A common mistake in painting a textured form in sunlight is to make the texture equally prominent throughout the form.
• The texture is very difficult to see at all in the shadow region

Diffuse light

all of the upward facing planes tend to be lighter since they recieve more of the diffused light

• in soft light, such as overcast light, there is no distinct light side, shadow side, terminator or core.