Perspective Direction identifies the fundamental direction in which a perspective process operates. Within Perspective Category Theory (PCT), perspective processes may be organised into two principal directional classes: the Viewing or Imaging Class and the Projecting Class.
This distinction is separate from Perspective Category. Category identifies a principal source or mode of a perspective process; Direction identifies the fundamental direction in which the relevant visual, optical, geometrical or spatial information operates.
Perspective Direction therefore provides a simple way of distinguishing processes that receive or form views and images from spatial reality from processes that project, construct or send images and spatial information outward from a source or model.
The Two Principal Directions of Perspective
PCT distinguishes two fundamental directional classes:
- Viewing or Imaging Class — perspective information proceeds from an object, scene or spatial source towards an eye, sensor, detector, image surface or imaging system.
- Projecting Class — perspective information proceeds outward from a source, image, model or representational system towards physical, optical, graphical or virtual space.
In simplified form:
Viewing or Imaging:
Object or scene → viewing / imaging process → view, image, measurement or model
Projecting:
Source, image or model → projecting process → projected or represented spatial appearance
These two directions may occur separately, but many perspective systems contain both directions operating successively within a larger process or image chain.
Viewing or Imaging Class
The Viewing or Imaging Class includes perspective processes in which information about an object, scene or spatial reality is received, gathered, formed, captured or recorded by a viewing or imaging system.
Light, radiation, spatial information or data generally proceeds from the object or scene towards an eye, image plane, sensor, detector or other receiving system.
Examples include:
- direct human and animal vision;
- retinal image formation;
- photography;
- camera imaging;
- telescopic and microscopic viewing;
- scientific imaging;
- surveying;
- photogrammetry;
- aerial and satellite imaging;
- remote sensing;
- scanning;
- measurement from images;
- computer vision;
- machine vision.
The resulting product may be a visual image, optical image, measurement, spatial model, recorded view or another organised representation of spatial reality.
The term captured perspective may sometimes be used descriptively for processes of this kind, but Viewing or Imaging Class is the broader PCT classification because not every receiving or image-forming process involves literal photographic capture.
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Projecting Class
The Projecting Class includes perspective processes in which light, images, geometrical information, shadows, models or other spatial information proceed outward from a source or representational system.
The source may be physical, optical, graphical, mathematical, instrumental or computational.
Examples include:
- geometrical projection;
- graphical perspective construction;
- projection from a station point;
- perspective shadows;
- cinema projection;
- slide and image projection;
- projected light;
- digital display systems;
- computer-generated projection;
- virtual imagery;
- augmented-reality imagery;
- holographic and related projected-image systems.
A projecting process may produce a physical image, projected image, graphical construction, virtual view, light pattern or represented spatial appearance.
The term projected perspective may describe the outward direction of such processes, while Projecting Class identifies their formal directional classification within PCT.
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Viewing and Projecting Compared
| Viewing or Imaging Class | Projecting Class |
|---|---|
| Information proceeds towards a receiving or image-forming system | Information proceeds outward from a source or representational system |
| Object or scene → imaging system | Source or model → projected appearance |
| Eye, camera, sensor or detector | Projector, graphical construction, display or projection system |
| Forms, captures, records or measures a view | Constructs, sends, displays or projects spatial information |
| Common in vision and imaging | Common in projection and outward representation |
The distinction describes the direction of operation, not necessarily the physical movement of a material object. In graphical, mathematical and computational systems, direction may describe the organisation or transformation of spatial information rather than the literal transmission of light.
Perspective Direction is not Perspective Category
Perspective Direction and Perspective Category answer different analytical questions.
Perspective Category asks:
What principal source or mode of perspective process is involved?
Perspective Direction asks:
In which fundamental direction does the perspective process operate?
A single Perspective Category can therefore contain processes operating in different directions, while a complete Perspective System may employ several categories and both directional classes.
For example, Instrument Perspective may include a camera operating principally within the Viewing or Imaging Class and a projector operating within the Projecting Class. Both are instrumental processes, but they perform opposite directional roles.
Similarly, New Media Perspective may combine image capture, computer processing, virtual modelling, display and projection within a single system.
Direction Within Perspective Processes
Perspective processes frequently contain several stages rather than one isolated operation.
A camera, for example, receives light from a scene and forms an image. This is principally a Viewing or Imaging process.
A cinema projector subsequently sends the recorded image outward onto a screen. This is principally a Projecting process.
The viewer then receives light from the projected screen through the eyes and visual system, returning the chain to the Viewing or Imaging Class.
A simplified cinema chain can therefore be written:
Scene → camera → recorded image → projector → screen → viewer
The complete chain alternates between viewing/imaging and projecting operations while also passing through several Perspective Categories.
Perspective Direction therefore helps reveal the organisation of complex image chains that might otherwise be described simply as one act of “perspective”.
Direction and the Perspective Image Chain
Many modern images result from a sequence of perspective processes rather than from one direct relationship between an object and an observer.
A digital photograph displayed on a screen may involve:
- a physical object or scene;
- natural and optical perspective;
- camera image formation;
- digital recording;
- computational processing;
- screen display;
- light travelling from the screen;
- retinal image formation;
- human visual perception.
Different stages may belong to different Perspective Categories while also changing directional class.
Perspective Direction therefore complements Category, Class, Type and the other analytical levels by helping identify how perspective information passes through the complete process.
Natural and Artificial Processes
The two directional classes should not be confused with the distinction between Natural and Artificial Perspective.
Natural / Artificial describes the source or mode of production of a perspective process.
Viewing or Imaging / Projecting describes its direction.
A natural process can therefore operate in a viewing or image-forming direction, while artificial systems may contain both viewing/imaging and projecting processes.
The classifications describe different characteristics of the process and can therefore operate together.
Direction and Technical Perspective
Technical Perspective includes systematic perspective processes that can operate in either principal direction.
Within the Viewing or Imaging Class, systematic processes may form, capture, record, measure or analyse spatial views.
Within the Projecting Class, systematic processes may construct, calculate, display or project spatial images and representations.
The directional distinction is therefore particularly useful for analysing instruments and technologies that reverse, combine or alternate perspective operations within one larger system.
Combined Directional Processes
Many perspective systems cannot adequately be described as operating in only one direction.
Photography, cinema, television, computer graphics, virtual reality, augmented reality, robotics and machine vision may contain several linked stages of viewing, imaging, modelling, displaying and projecting.
A complete system may therefore:
- receive spatial information;
- form an image;
- measure or transform that image;
- construct a model;
- generate a new view;
- project or display the result;
- allow that result to be viewed again.
PCT can treat these as related stages within a perspective chain rather than requiring the complete system to be classified according to only one directional operation.
Why Perspective Direction Matters
The distinction between Viewing or Imaging and Projecting helps clarify processes that are frequently grouped together under the single word perspective.
It helps distinguish:
- seeing from displaying;
- image formation from image projection;
- capture from outward projection;
- receiving information from sending information;
- a camera from a projector;
- retinal image formation from projected imagery;
- individual stages within complex perspective chains.
Perspective Direction therefore provides an important organising principle within Perspective Category Theory. It does not replace Perspective Category, Type or Form; it introduces another analytical question that helps reveal how a perspective process actually operates.
A Directional Framework
Perspective Direction can be summarised through two basic questions:
Is spatial information being received, viewed or formed into an image?
→ Viewing or Imaging Class
Is an image, model, construction or spatial pattern being projected or produced outward from a source?
→ Projecting Class
In simple systems the answer may identify one directional class immediately. In more complex systems, both directions may occur repeatedly within a chain.
Perspective Direction is therefore best understood as a way of tracing the directional organisation of perspective information through natural, optical, graphical, instrumental and computational processes.
Related Pages
- Viewing or Imaging Class → perspective processes in which views or spatial information are received, formed, captured or analysed.
- Projecting Class / Perspective Projection → perspective processes in which images, light, constructions or spatial information are projected outward.
- Perspective Category Theory → the wider analytical and classificatory framework for organising perspective.
- Perspective Category → principal sources or modes of perspective processes.
- Perspective Process → the operations through which perspective images, views and representations are produced.
- Perspective System → organised combinations of perspective principles, processes and methods.
Explore Theory
Explore the principal theories, classifications, types, forms, geometries, spatial concepts and visual phenomena of perspective.
Foundations & Classification
Perspective Category Theory · Perspective Category · Perspective Direction · Viewing or Imaging Class · Projecting Class / Perspective Projection · Perspective Process · Perspective System
Direction & Process
Viewing or Imaging Class · Projecting Class / Perspective Projection · Perspective Image Chain
Further Reference
Abridged Dictionary of Perspective · Theory & Concepts Index · Perspective Types & Forms