Lighting: Spherical Fundamentals Part 1

This study will take us down a little rabbit hole of a breakdown of the diagram below. The main focus is on how lighting is lighting. The same concepts that apply to a small ball lit by a lamp apply to planets lit by a star. I personally find these types of comparisons helpful when studying lighting because I focus on the concept rather than the context.

I’ve found this image to be incredibly helpful not just in building vocab, but in learning that all of these concepts can be in play at once to make a varied and dynamically lit image.

Reflected Light

Reflected light is exactly what it sounds like. The image below shows the reflected light from the key illuminating the underside of the ball.

This can be found in space. For example on our Moon gets bounce light when the Earth is hit by its key light (The Sun):

“ A new Moon occurs when all of the Sun’s light is reflected away from Earth, and the side of the Moon facing Earth is barely visible... Sometimes the dark face of the Moon catches Earth’s reflected glow and returns that light. The dark face of the Moon has a faint shine, a ghostly version of a full Moon. The phenomenon is called earthshine. It tends to be brightest between April and June, though it does occur at other times of the year. “ 

-NASA, https://earthobservatory.nasa.gov/images/83782/earthshine

While Space is known for not having fill light, the moon Enceladus is illuminated by two light sources (A sun key light and a bounce from Saturn) in this photo by NASA. (Right photo enhanced to see reflected light.)

 You may have noticed a shadow line on the Moon in the photos above between the light and reflected light. This only appears on rounded forms and is a “core shadow”.

Core Shadow

Core shadow is the line of shadow between two light sources:

Shown on Saturn when its rings reflect light back onto the planet:

I like to think of the core shadow is a 3D lighting design tool that is best explained in 2D. The 2 images below show a key/shadow design, and a core design (key, shadow and rim/reflected light)

This creates a core shadow design. Notice how stringer visual weight is given to the shadow when it is contrasted with lighter values on both sides.

Because core shadows only appear in rounded areas, the can be used to emphasize 3D shape and modeling. A core also adds value range to the subject.

Core shadow can lead the eye across a form as a composition tool. It can also appear across every rounded area on the body - In the second image, there’s a core shadow from reflected light on the hand, chin, breasts and even both feet.

Notice how each character, even the metallic one, has a core shadow both in their face and a core running down their bodies.

Live action examples: