Illusion of Depth vs. Actual Depth

In sculpture, the term “relief” means to raise out of the background. In contrast to “in-the-round” sculpture, a relief is seen essentially from the front, as is the case with traditional flat art forms. However, unlike paintings, drawings, prints, and photographs, relief sculpture requires raking light to reveal its forms. Shadow and light reveal tonality and give the sculpture dimension.

Soldiers crossing Hill, cutting and carrying trees, 859-824 BCE, bronze repousse, 14 1/4 in. (36.2 cm), from Imgur-Enlil (present-day Balawat, Iraq)

 

ILLUSION OF DEPTH vs. ACTUAL DEPTH

There are many visual tools available in creating an effective feeling of depth in relief sculpture. Perspective allows the artist to create an illusion of depth greater than is actually present.  Perspective has many variations that trick the eyes in different ways. All are based upon our mind’s ability to find patterns that cue us into understanding the real world. However, it is an optical illusion to see great depth in paintings, photography and relief sculpture.

It is also possible to create relief by employing actual depth.  In this case, there is no attempt to trick the eye, because its forms are reality rather than illusion. Examples of actual depth relief sculpture can be found in many architectural facades, and may be composed of geometric or organic forms. actual depth can also be partially employed in certain high relief sculptures, described later.

In the Monotone Relief image shown above, the illusion of great depth is achieved through tricks of perspective. Whereas, no attempt to trick the eye is found in the images below.   

 

      

Architectural Relief Sculptures in San Francisco, employing actual depth rather than perspective

 

FORCED vs. HIERARCHICAL PERSPECTIVE

An illusion of depth can be achieved by understanding visual perception. Forced perspective is when the brain is tricked into believing that an object is further away in comparison to another through the application of scale. Hierarchical perspective employs variation in scale as well, but not for the illusion of depth; instead, it defines the relative importance of individual objects. One or the other effect will be achieved with the application of further visual cues. Forced perspective works when the illusion feels natural, whereas Hierarchical Perspective requires the elimination of alternate visual cues.

Forced Perspective versus Hierarchical Perspective

 

       

The Story of Jacob and Esau by Lorenzo Ghiberti (left) shows principles of forced perspective. The Palette of King Narmer (right) illustrates hierarchical proportions, with the Egyptian King Narmer looming large over both his enemies and attendants.

OVERLAPPING PERSPECTIVE

“Overlapping Perspective” places one object in front of another to achieve depth. This is especially effective when the foreground object overlaps only one of the background object’s vertical edges, so that the other vertical edge is still fully visible. In the left image, below, the background object is partially obscured.  To the right, it is not, and might just as well be sitting atop the foreground object. The illusion of overlap in a monotone relief is made by carving back (or tapering) the object that is behind the other. In reality, they can be at the same height above the background surface, yet with this fine taper appear to overlap.

Effective and ineffective Overlapping Perspective

 

ATMOSPHERIC PERSPECTIVE

Atmospheric perspective is an illusion of depth created by tonal differences combined with a flattening effect, and overlapping perspective. Distant objects appear lighter, less saturated, and flatter due to the density of particles in the atmosphere, which obscure details and darker tones. At the most extreme, almost all tone flattens into the sky, except for large, bright objects such as snow caps.  This is most effective in landscapes depicting vast distances, or closer settings in fog and heavy rain.

In relief sculpture, atmospheric perspective is achieved by flattening out and thinning distant objects, and eliminating details. The edges of the most distant objects become very thin, creating only a faint line of light to define the form. The distant forms become flatter, with only the faintest contrasting shadow or highlight detail, and they take on the same tone as the sky.

Atmospheric perspective is the result of obscuring effects of air and particulates, such as fog, sleet, rain, snow, smoke, dust and smog. Over distance, the thickness of atmosphere is greater, thus the visual transition from object to atmosphere. Visual flattening occurs when objects lose their tonal contrast and become lighter.

Atmospheric Perspective is achieved by thinning and eliminating details

Detail of Pure and Remote View of Streams and Hills, Xi liu yu shan po by Xia Gui, Song Dynasty, ink on paper, 46.5 x 889.1 cm

CITATIONS

Anonymous (Assyrian). Soldiers crossing Hill, cutting and carrying trees. 859-824 BC. Artstor, library.artstor.org/asset/AWALTERSIG_10312545218

Sculpture of the Paradise gate form the Baptistry by Lorenzo Ghiberti, Stories of Isaac, original restored from Opera del Duomo Museum, from Florence, Italy. Attribution: Sailko, CC BY-SA 3.0 <http://creativecommons.org/licenses/by-sa/3. 0/>, via Wikimedia Commons

"Palette of King Narmer" Links to an external site. by profzucker Links to an external site. is licensed under CC BY-NC-SA 2.0 Links to an external site.

Xia, Gui, fl. 1190-1224. Pure and Remote View of Streams and Hills: det., Xi liu yu shan po. [n.d.]. Artstor, library.artstor.org/asset/ARTSTOR_103_41822003004825