Illusion / Immersion Function

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Illusion / Immersion Function concerns the use of perspective processes to create, modify or organise appearances so that a viewer experiences a spatial condition that differs from, extends beyond or becomes integrated with the immediate physical situation.

Illusion and immersion occupy an important position within perspective because they reveal that perspective does more than record or measure spatial reality. Perspective can also be used deliberately to construct appearances and to influence how a viewer experiences space, scale, depth, position, form and visual presence.

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Illusion as a Perspective Function

A perspective process performs an Illusion Function when it produces an appearance that leads the viewer to perceive or interpret spatial properties differently from the underlying physical arrangement.

The altered appearance may concern apparent:

• size;
• shape;
• depth;
• distance;
• position;
• orientation;
• dimensionality;
• transparency;
• movement;
• continuity; or
• the viewer’s relationship to the represented space.

An illusion need not involve deception in any negative sense. It may simply be a deliberately constructed visual effect through which an image or environment produces an appearance different from its physical support or construction.

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Principal Illusion / Immersion Operations

Within the PRC Functions of Perspective framework, the principal operations include:

• Visual illusion — an altered or misleading appearance experienced visually;
• Graphical illusion — an illusion constructed through drawing, representation or graphical organisation;
• Instrument illusion — an appearance generated or transformed through an optical or technical instrument;
• Forced illusion — a deliberately constructed spatial arrangement designed to produce a particular perspective appearance;
• Apply Perspective Phenomena — deliberately use perspective effects to modify or construct an appearance; and
• Mimesis / Immersion — construct an appearance or environment that represents, simulates or incorporates the viewer into an apparent spatial reality.

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Visual Illusion

A visual illusion occurs when the appearance experienced by an observer differs in some significant respect from the physical or geometrical condition producing it.

Perspective contributes to many such effects because apparent size, shape, depth, direction and position depend upon viewpoint and the spatial relationship between observer, object and image.

Some illusions occur naturally through visual and optical processes. Others are deliberately constructed.

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Graphical Illusion

Graphical illusion uses represented perspective relationships to create an apparent spatial condition on or through a picture surface.

A physically flat image may appear to possess depth, recession, volume, distance or spatial continuity. Conversely, deliberately altered perspective relationships may make represented forms appear distorted, unstable, impossible or spatially ambiguous.

Graphical perspective therefore provides both methods for producing convincing spatial appearances and methods for deliberately departing from ordinary spatial appearance.

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Instrument Illusion

An Instrument Illusion is produced or transformed through an optical, photographic, electronic or other technical system.

Lenses, mirrors, cameras, projectors, displays and other instruments may alter apparent scale, field of view, shape, position, depth, orientation or spatial relationship.

The resulting appearance may be intentionally designed or may arise as a consequence of the optical or technical properties of the system.

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Forced Illusion

Forced illusion depends upon deliberately arranging physical objects, distances, scales, viewpoints or image elements so that the resulting perspective appearance produces a different impression from the underlying spatial arrangement.

Forced perspective is a familiar example. Objects of different physical sizes may be placed at carefully controlled distances so that, from a selected viewpoint, they appear to possess a different relative scale or spatial relationship.

The illusion is therefore produced through the physical organisation of perspective relationships rather than solely through graphical representation.

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Applying Perspective Phenomena

Perspective Phenomena can be deliberately applied as tools for constructing appearances.

Changes of apparent size, shape, overlap, foreshortening, convergence, clarity, colour, depth and spatial position may be organised or exaggerated to influence how a represented or constructed space is perceived.

The same phenomenon may therefore occur naturally in one context and be deliberately applied as an Illusion Function in another.

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Immersion

Immersion extends the construction of perspective appearance from an image that is viewed from outside to an environment or system within which the viewer appears to participate.

The viewer may be visually surrounded by, embedded within or interactively connected to a represented or simulated spatial reality.

Immersion may be produced through panoramic imagery, stereoscopic systems, projection environments, virtual reality, augmented reality, simulated spaces and other New Media systems.

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Mimesis and Spatial Presence

Mimesis concerns representation or imitation of spatial reality. Perspective contributes to mimesis by organising images and views so that spatial relationships appear coherent or recognisable.

Immersion goes further by increasing the viewer’s apparent spatial involvement with the represented environment.

The two processes can therefore form a continuum from representing a spatial reality to creating a sense of presence within it.

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Illusion / Immersion and the Represent Family

Within the compact Functions of Perspective map, Illusion / Immersion is grouped beneath the broad Represent family because these operations construct or transform appearances of spatial reality.

This grouping should not be taken to mean that illusion and immersion are merely forms of ordinary representation. In the broader Goals of Perspective framework, creating illusion and producing immersion may also be treated as major goals in their own right.

The Function map therefore describes the operational relationship, while the Goals framework describes the larger purpose for which the operation may be employed.

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Illusion / Immersion and the Two Perspective Classes

Illusion and immersion may involve the Viewing or Imaging Class, the Projecting Class, or a sequence combining both.

An image may first be captured or generated and subsequently projected, displayed or presented to the viewer. The viewer then observes the resulting appearance through another image-forming process.

Complex immersive systems therefore frequently involve chains of perspective processes rather than one isolated direction.

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Illusion / Immersion as Function, Goal and Outcome

Illusion and immersion can appear at more than one conceptual level depending upon the question being asked.

As a Function, they describe what the perspective process does: it creates or organises an appearance or immersive spatial experience.

As a Goal, they describe why the perspective system is being used: to create illusion or produce immersion.

As an outcome, they describe the resulting visual or spatial experience produced for the observer.

These uses are related, but they should not be collapsed into a single analytical level.

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Illusion / Immersion Within the Analytical System

On this page, Illusion / Immersion is being considered specifically at the Function level of the seven-part analytical system:

• Category — principal source or mode;
• Class — fundamental direction;
• Type — method, system or process;
• Form — resulting appearance;
• Phenomenon — visible or detectable effect;
• Function — what the process does; and
• Product — what the process produces.

Illusion / Immersion therefore describes an operation that may occur within many different Perspective Categories, Classes and Types rather than constituting an additional basic Perspective Class.

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Related Perspective Topics

Functions of Perspective →
Goals of Perspective →
Representing — Goal of Perspective →
Modelling Function →
Classification Function →
Measurement Function →
Observation Function →
Capture / Project Function →
Graphical Perspective →
Instrument Perspective →
New Media Perspective →