We present terminology related to the subject of ‘Optical Perspective’.

Wherein said terminology relates specifically to Perspective Category Theory (PCT), which aims to unite all facets of Visual / Optical Perspective, or the Technical and Non-Technical forms of Perspective, under a single framework. The following list of perspective concepts does not seek to provide a comprehensive list of all terms that relate to Optical Perspective; but instead defines many of the new (and older) words that map to unique or particular meanings in respect of PCT.

To see a comprehensive list of all terms related to Optical Perspective, consult our Dictionary of Perspective and the related Encyclopedia of Perspective.

PCT Lexicon

It is helpful to summarise Perspective Category Theory, in the form of the basic terminology we employ to identify perspective categories, plus to characterise perspective goals, processes. and outcomes, etc.

Perspective ConceptDefinitionProcess / Outcomes
Perspective Category TheoryA scientific theory of Optical Perspective, developed from first principles and with a complete set of foundational concepts—that purports to represent all of the different facets of said phenomena.Optical Perspective related terms, concepts, principles, phenomena, goals, methods, forms, products, functions, applications, etc.
PerspectiveFormation of an Image—or a representational pattern—of a state of affairs present in a spatial reality.Image is formed by a range of natural and/or artificial processes.
ClassTwo main classes: Visual Perspective and Symbolic Perspective.Visual or Symbolic Image.
Visual Perspective 
(First type or not related to human vision)
When a Visual Image is used to view, match or represent the visual appearance of a three-dimensional object/scene.Visual Image is typically formed by an Optical Process (see below), or a Contact Process.
Visual Perspective 
(Second type or human vision)
Direct looking at reality using human or animal vision.View of a three-dimensional form / scene (Involves both physical or geometrical optics and also psychological optics).
Contact PerspectiveDirect mapping of spatial form, namely a spatial object/scene, by utilising physical contact using one, two or three dimensional examination procedures (1D/2D/3D space).Handling or Moulding Perspective (Visual Image).
GoalsThe primary goals of Optical Perspective (all types) are viewing, matching, and making representations of a spatial reality. Technical Perspective has slightly more precise goals: Prescribing, Indexing and Modelling spatial reality.Perspective Products. Certification of sight, measurement, and representation.
Optical PespectiveVisual Image (or view) of a three-dimensional reality created primarily using light (may involve real, virtual, or simulated/modelled light rays).Visual Image formed by an Optical Process (See below).
Optical ProcessOptical Perspective is the production of an Optical Model (or Visual Image) that is the outcome of a systemic Optical Process comprised of a set of imaging and/or modelling procedures.Optical Perspective operates wherever a real, simulated, or modelled optical view/image of a spatial reality is produced (by whatever method). Five kinds of Optical Process exist: Optical Imaging, and Mathematical, Graphical, Optical and Computer Modelling.
Optical Process Overloading
Optical Perspective operates when an optical view/image of a spatial reality is produced by an Optical Process of a specific type. However sometimes more than one type of Optical Process is involved simultaneously, being a process called Optical Process Overloading. It is often the case that several different modelling processes are involved in producing a particular perspective image. For example, movie Computer Generated Imagery (CGI) typically involves Mathematical, Graphical, Optical, and Computer Modelling simultaneously.
World TheoryOptical Perspective (typically) seeks to explore the Physical World by using the Optical World to probe spatial reality accurately or with sufficient realism.

Occasionally artists/scientists create other kinds of Optical Perspective to explore aspects of the Visual or Optical World (for example).
The natural products of human vision are named as the Visual World (unaided eyesight)—or the transformation of the Optical World according to the rules/processes of human vision (ref. physiological and psychological optics). The Represented World refers to the depiction of aspects of the Physical, Optical, or Visual World(s).
Technical Perspective (Ref. Optical Perspective)Systematic process that produces a detailed visual image, measurement, representation, model or view, of a three-dimensional object or scene.Visual Image (or view) is formed using optically, mathematically, geometrically, or logically correct, known, and consistent principles.
Categories of Technical PerspectiveThere are six primary categories of Technical Perspective which encompass the vast majority of perspective methods employed in modern times.Natural (includes Visual Perspective of second type or human vision), Mathematical, Graphical, Instrument, Forced, and Media Perspective(s).
Category OverloadingThe different Categories of Perspective enable us to identify which types of perspective phenomena are operating in a practical situation. However sometimes more than one Category is involved simultaneously to produce a particular perspective image, being a process called Category Overloading.Notice that Linear Perspective is both a form of Mathematical and Graphical Perspective simultaneously. Hence a particular perspective image/view may fall under more than one category. Most types of perspective involve mathematical principles, or Mathematical Perspective, to one degree or another. Similarly, all kinds of Visual Perspective (2nd type) involve Environmental Perspective, etc.
Non-Technical PerspectiveNon-Technical Perspective is defined as any non-systematic process that produces a detailed visual image, representation, model or view, of a three-dimensional object or scene.Visual Image (or view) is formed using optically, mathematically, geometrically, or logically incorrect/unknown/inconsistent principles.
Spatial Mapping
(ref. Graphical Perspective)
Graphical Perspective can be defined in spatial terms as follows: A three-dimensional Object located in a three-dimensional Object Space (real, virtual, or imaginary) is transformed into a two or three-dimensional Image located in two or three-dimensional Image Space (real or virtual).Typically perspective is a staged mapping transformation, which may include different types of space, including one or more of the following: Natural (Physical), Visual (2nd type), Mathematical, Graphical, Optical, Instrument, Illusory (real/virtual), and Media space(s), etc.
Visual FeaturePerspective prescribes how an object’s Visual Features appear from a particular location and angle-of-view, distance, scale, etc; and according to a specific observation scenario.Visual Features include points, lines, plane figures, solid shapes, shades, shadows, reflections, translucency, colour, texture, size, etc.
Visual TransformationA particular instantiation of a Category of Perspective reflects a corresponding group of visual changes that occur while viewing/surveying/representing a three-dimensional scene (particular case).Apparent optical adjustments to Visual Features for an individual imaging scenario.
FormA number of different Perspective Forms are possible for each Perspective Category.Example: Graphical Perspective (e.g. Linear Perspective) can manifest itself in a variety of Forms, including in a drawing, painting, computer-generated image, virtual reality, etc.
Perspective PhenomenaA general category of perspective demonstrates, and is recognised by, certain Perspective Phenomena. The Perspective Phenomena refers to all of the intrinsic changes to Visual Features that occur according to a particular Category of Perspective and its inherent processes.Patently each class of perspective will exhibit a unique set of Perspective Phenomena, whereby certain phenomena are shared (or embodied) by a number of different categories of perspective. Embodiment of the Perspective Phenomena may happen by certain naturally occurring visual processes, or else by human design, but irrespective of cause we refer to the instantiation of said phenomena as the Methods of Perspective.
MethodA Perspective Method is any practical or theoretical technique that aids in forming a detailed visual image, measurement, representation, model or view, of a three-dimensional object or scene.Typically one or more Perspective Methods are combined to render an image according to a particular Category of Technical Perspective. Practical examples include Perspective Instruments such as a lens, camera, the perspective window, planisphere, projector, computer, etc. Perspective Methods include all instrument design features plus operating methods. Examples of theoretical methods include a particular projection method/algorithm, vanishing point(s), field-of-view, projected scale etc.
ProductA detailed visual image, measurement, representation, model, or view, of a three-dimensional object or scene.Visual Image or related aspect.
FunctionViewing, prescribing, matching, modelling, exploring, representing, and mixing images, of a three-dimensional reality.Applied to multiple application areas.
Systemisation of Space and TimePerspective works to prescribe, index, and model spatial reality; Technical Perspective enables accurate systemised worlds to be developed on media.Using Technical Perspective, we can approach objects from different viewpoints and scales, leading to distinct visual/geometrical functions that can be isolated, catalogued, and explored.



Alan Stuart Radley (2023).


Radley, A.S. (2023) 'Perspective Category Theory'. Published on the Perspective Research Centre (PRC) website 2020 - 2023.

Radley, A.S. (2023) 'Dimensions of Perspective', book in preparation.

Radley, A.S. (2023) 'The Dictionary of Perspective', book in preparation. The dictionary began as a card index system of perspective related definitions in the 1980s; before being transferred to a dBASE-3 database system on an IBM PC (1990s). Later the dictionary was made available on the web on the SUMS system (2002-2020).

Copyright © 2020-23 Alan Stuart Radley.
All rights are reserved.