Lighting Issues 02

The last post examined some of the different kinds of light and light sources use in cinematography and design rendering. The former uses many specific lights (key, fill, kicker, bounce, ambient, spot, direct, etc.) while the latter may incorporate only a few of these in a drawing. For many designers, understanding how light illuminates form, surfaces and details represents a lifelong education. Unless you are creating a design that looks exactly like a geometric object (cube, cone, cylinder or sphere, solids traditionally studied in school from a light perspective), you may not have a good precedent for how light interacts with the surface, creating shade, cast shadows and highlights. Even the best visualizers must use some sort of existing example to predict, on paper, what a solid object will look like with light shone on it.

A good method to initiate this process is to find or supply a single light source (sunlight or a flashlight) and place representative solids in position to exhibit the same conditions represented in the drawing (Fig.01.)

Fig01 - A simple object in natural sunlight to understand shading/cast shadows.

An alternative, more easily done now than before, is to model the shape in a computer program (Maya) and configure relative light conditions.

In Industrial Design a concept sketch uses a cast shadow to help define the form of the product by integrating a dark background that, in contrasting with the lighter tones of the focal point, helps to generate the impression of three-dimensionality and reality that a line drawing or simple shading cannot (Fig.02.)

Fig. 02 - Outdoor grill concept sketch

Additionally, there are added benefits to establishing a light system for the concept drawings. Incorporating a hierarchy of light and colored light sources helps to define visual depth. Syd Mead, a long-time designer, 'futurist' (as he refers to himself), and visualizer is a master of integrating warm and cool light sources to create a sense of great depth beyond the picture plane (Fig.03.)

Fig.03_ Syd Mead

There are three components: first, a key light used for primary imaging, often associated with parallel light rays ('infinite' light in cinematographic terms); second, ambient or reflected lighting that adds depth and complexity to the reflected light in the shadows - often a warm ground tone; third, reflected light from the distant horizon or sky - often a cool, bluish tone - seen on the rear trailing surfaces of the product. This latter may be termed a kicker or bounce light. Even though the concept sketch may be of an interior product, using warm and cool contrasting tones helps with the shadow to create the 3D characteristic. See Figure 01 for directions the lights may originate from.


Figure01 - General ID product sketch lighting scenarios

A good example of this kind of image is shown in Figure 02 of a gouache rendering of a John Deere tractor in 1940 for Henry Dreyfuss Associates. A strong cast shadow with warm fill tones in front and underneath and cooler sky tones reflected on top and trailing surfaces offer a near-photographic if muted quality of visualization.



Fig.02 - Flinchum, R. (1997), Henry Dreyfuss, Industrial Designer - The Man In The Brown Suit. New York, NY: Rizzoli International Publications. p.120



Unfortunately, there is no formula for calculating or adjusting the intensity, color and configuration of each of the light sources indicated here. The rendering's effectiveness is generally a result of direct observation from life and techniques of other designers as well as some level of instruction. As can often be the case, each designer will choose a preferred method of visualization and adapt it to his/her process.

In Maya and computer rendering, however, the ability to control, adjust, manipulate, and configure these variables is so powerful, any one task may not ever approach the software's capacity. Accordingly, one must learn each well enough to understand the repercussions of settings intended or not as exhibited in my first crude examples.

The mental models used to light a product are also different between drawing and computer rendering. Fill lighting, for example, cannot be assumed to reflect off a ground plane and upward into the underside of an object; it may be projected from a viewpoint within inches of the object even if the final effect resembles a lightsource far away in real life. Figure 03 shows the positions of the key, fill, and bounce lights. The light positions, accordingly, must be adjusted if the perspective view is changed to make sure the viewed surfaces are reflecting light and are properly illuminated for the observer.

Fig.03 - Maya image of solids with key, bounce and fill light positions and effects

As indicated in the previous post, composition of the physical elements should be considered not just for maximum views of surfaces and details but also to use highlights and cast shadows of one solid or area as backgrounds to another subject to help create a visual perception of depth. Cinematographers use spot and

rim lights to isolate and frame subjects in the process of creating a visual hierarchy so the viewer is never confused about what he/she should focus their attention on.

The next post will begin to examine the process of casting shadows in drawing and in 3D rendering.