“A well-trained eye for the appreciation of form is what every student should set himself to acquire with all the might of which he is capable.”
Harold Speed - The Practice and Science of Drawing, 1913
1. Intention
The motivation for this lesson is to provide a bridge for the beginner/intermediate artist to move from a classical understanding of form towards an understanding which is more suitable for realizing the content of the modern imagination.
Often, contemporary art teachers present drawing from the imagination as taking on the same orderly process as an academic drawing (whether it be a portrait, still life, landscape, etc). However, more often than not, the imaginative artist at some point in their work opens the chaotic stream of the subconscious and paints in varying artistic elements. Without proper analytical thinking this stream manifests into the painting as an incoherent arrangement of ideas. To produce cohesion and establish realism we combine our classical understanding of form with modern analytical ideas.
2. Tonal Model
Essentially, form is the illusion of 3D surface arising from the 2D synthesis of tone (relative brightness, or value) and line. Round surfaces (feminine) and flat surfaces (masculine) are the conceptual building blocks of every form ever rendered.
James Gurney - Color and Light (page 46)
“Light striking a geometric solid such as a sphere or cube creates an orderly and predictable series of tones. Learning to identify these tones and to place them in their proper relationship is one of the keys to achieving a look of solidity.”
Rendering is the process by which the illusion of form is produced. The most canonical process of tonal rendering is to apply tone with respect to a single light source on an object which is solid. In this way, stunningly realistic images have been produced in the controlled environments of the ateliers (such as the image above).
This image above depicts theoretically perfect models created in the open source rendering software, Blender. Such an image allows us to analyze the concepts themselves, purely, without the unwanted variables we encounter when drawing from life (another skill to be learned, but not the focus of this course).
3. Constructive Model
In order to draw from the imagination, artists may begin to build a more robust mental representation about the geometrical surface or “frame” of a particular object so that form can now be analyzed in a way which is separate from the light/material used to render it.
We do not need to see an object painted with respect to a light source to feel its form. Envisioning the surface of your imaginary object as a simplified construction of round and flat surfaces is the essence of the classical idea of “blocking out” form.
Contemporary artists have built entire careers from rendering their forms constructively (such as the image above). One may find this model most easily be understood visually through “hatching” or “cross-hatching”, but tonal gradients often go hand-in-hand with constructive rendering.
4. Occlusion Model
As we render more complex imaginary objects it often becomes essential to have a tonal process which is not subject to the constraints of the single-light tonal model or constructive model. By neglecting the effects of a hard light source we can peer into the soft interaction of ambient light “between” and “around” objects. We refer to this interaction as occlusion.
This model of rendering allows the artist to coherently and very expressively create form without regard for as many distinct tones as the tonal model. In essence, we are conveying the unobstructed surfaces as the brightest. This is because ambient light (the infinite light bouncing from all directions in a scene) is most likely to reflect towards the viewer in those areas.
The above image depicts the tonal model on the left, and the occlusion model on the right. Notice how the occlusion model on the right lacks cast shadow and reflected light, as it instead focuses on the natural shadows between geometric intersections, but still conveys a strong sense of form.
For example, consider walking in a dense forest where the sun above does not directly penetrate the trees and cause hard cast shadows. There is still light gathering around you (and thus shadows between and around objects) because of the infinite bouncing behavior of light rays. This is a natural approximation of the effect, but we are interested here in simulating that behavior perfectly.
5. More Models…
The imaginative artist often seeks to express a variety of light sources over a variety of materials, such as “crystals emitting light across a shimmering lake” or “cosmic aura emerging from the palm of a woman’s hand”. Not only that, but often we desire to render things-as-other-things, such as rendering “a sword made of light” or “holographic city”. More often than not, we desire even a combination of the two! In the previous sections we explored rendering models which serve as a basis for these ideas.
Summary
By combining classical theories of form with modern analytical ideas we can more freely and coherently express our imaginations
The tonal model uses 1 light source (simple case) and observes tonal shifting
The constructive model represents geometric surfaces with curve and line
The occlusion model conveys shadow around and between objects
In future lessons models like cloud, crystal, cosmic, etc. will be explored and reference these exact models we have defined in this lesson