Surfaces and Effects

Transmitted Light

Transmitted Light

• light that bounces off the surface is fairly dull in comparison
• when sunlight travels through thin material the light becomes richly colored
• four kinds of light on leaves:
• transmitted light
• leaf facing downward is the darkest green
• up facing planes are blue-green
• sunlight reflects off the top surface of a leaf

Surface Scattering

Subsurface Scattering

• light enters the skin and spreads out beneath the surface, creating an unmistakable glow
• shows up when; flesh is translucent, small forms, and backlighting

Color Zones of the Face

Color Zones Of The Face

• forehead is a light golden color
• free of muscles
• from the forehead to the bottom of the nose is reddish
• blood is carried closer to the skin's surface
• the zone from the nose to the chin tends towards a bluish/greenish/grayish color
• blue-cast from hair follicles
• helps to bring out the red lip color
• zones are more pronounced in men

The Hair Secret

The Hair Secret

• use big brushes, keep the masses simple, soften the edges, control the highlights
• if the edges are hard where the hair meets the forehead, it tends to sit like a helmet
• visualize masses of hair like ribbons
• when hair is shorter, the highlight extends across the entire head

Caustics

Caustics

• spots, arcs, or wavy bands of light projected onto a surface by means of refraction or reflection
• occurs from curved glass or water
• the light bunches up and forms lines of concentration along the boundary of geometric shapes
• shapes are determined by the curvature of a surface
• underwater caustics:
• waves focus a network of lines on the seafloor
• don't occur much deeper than 20 or 30 ft
• only visible on sunny days and the top surface of underwater forms
• caustic reflections
• cast upward from wavelets
• when the sunlight shines through curving glass or reflects off shiny, metallic surfaces

Specular Reflections

Specular Reflections

• an object with a shiny surface is like a mirror-it reflects an image of whatever is around it
• light rays bounce off the surface at the same relative angle they approached it
• in diffuse reflection, light bounces in all directions (matte surfaces)
• Rules
• the more reflective the surface, the broader the range of values you need to paint
• convex surfaces reflect a mini view of the scene around the object (including elements beyond the limit of the composition)
• it is a separate layer added on top of the usual modeling factors

Specular Highlights

Highlights

• specular reflections of the light source on wet/shiny surfaces
• specular highlights: 
• the highlight on any glossy form is not a pure white, but rather a combination of the color of the source and the color of the object
• annular highlights
• highlights also form into patterns of circles made up of individual scratches, twigs, etc.

Color Corona

Color Corona

• an extremely bright source is often surrounded by a region of colorful light
• sometimes called a lens flare
• creates a chromatic halo around the source
• a color corona can make a source seem brighter than the white of the paper and actually make the viewer squint 

Speed Blur

Motion Blur

• Two types of blurring: motion blur or speed blur
• motion blur
• the form moves rapidly in front of a stationary observer
• has a softly, blurred edge
• the faster a form is moving, the more it is blurred
• a slower drying medium helps the figure blend with the background
• speed blur
• the camera tracks along with a fast-moving object
• background blurs radially from the vanishing point
• the blur gets more extreme near the edges of a picture
• the edges running along the path of action stay sharp
• lay the colors in wet paint and blend the edges with a soft brush

Photos vs Observation

Photos vs Observation

• cameras tend to distort light and color in the following ways:
• deep shadows will appear black, bright highlights will appear pure white
• colors tend to weaken or shift in chroma, and become more monochromatic
• weak sources, such as reflected colors from nearby objects, are lost
• using photos without losing color
• make a quick color note in your chosen medium
• turn references into black and white images, that way you won't be influenced by the photographic color
• wait for overcast days
• take two exposures; one for the darks, another for the lights