Jean Auguste Domnique Ingres (1780–1867)The Grand Odalisque, 1814, Oil on canvas, 35 13/16 × 63 3/4 in (91 × 162 cm)
DESCRIBING THREE-DIMENSIONAL FORM IN TWO DIMENSIONS
Rendering three-dimensional forms on a two-dimensional surface is one of the central recurring tasks of representational painting. While both ancient and medieval painters made some headway with rendering, it wasn’t until the Renaissance that artists finally discovered how to make a completely comprehensive and consistent description of form in space. An early example is The Marriage of the Arnolfini by Jan Van Eyck (1390–1441), painted in 1432. The artist has succeeded in meshing extremely credible drawing with meticulous tracking of the tonal and color changes across all the various forms in the painting. In Italy, artists made a similar journey from an essentially linear art to a fully rendered version of three-dimensional form. The High Renaissance found Michelangelo, Raphael, and Leonardo da Vinci all demonstrating mastery of rendering.
In practice, successful rendering of form relies on three interlocking tasks. First, the drawing or outline must be accurate. Second, the tonal change across the form as the light strikes it must be recorded accurately. Third, the color change across the form must be tracked with some precision.
One of the features of rendering that presents the most difficulty is the change of color with the play of light across the form. When a form is illuminated, the viewer perceives the color to be different at each point on the object. Usually it is not sufficient when rendering a form to simply adjust the tone of the local color. It is rather necessary to secure a sense of the changes of the optical or perceived color.
See also: Underpainting on page 202
• Monochrome underpainting
Painting an image in a monochrome, usually a muted warm color, allows for adjustment of drawing and tone before the business of color is addressed. The color is applied on top in glazes or with stippling so that a sense of the underpainting is transmitted from beneath. This usually results in a more powerful sense of form.
• Grayscale and palette control
Academic painters often found it advantageous to lay out a grayscale on the palette and then mix color in strings or runs, using the grayscale to accurately measure the tonal position of the color.
• Finish
Rendering smooth forms, such as flesh or fabric, can require soft gradations that involve blending painted surfaces. Traditionally, artists use a fan brush to achieve this, dragging the very top of the paint surface in multiple directions with a light touch.
Jean Auguste Domnique Ingres (1780–1867)
The Grand Odalisque, 1814, Oil on canvas, 35 13/16 × 63 3/4 in (91 × 162 cm)
Ingres left unfinished this second version of The Grand Odalisque, revealing his underpainting technique. Color would have been added in glazes on top of this monochrome rendering.
