A Perspective Image / View is a visual outcome through which a spatial object, scene or represented spatial reality is seen, imaged, projected or represented according to a perspective process or system.
The terms Perspective Image and Perspective View are closely related but should not always be treated as identical.
In the principal distinction used here:
Perspective Image → a fixed visual representation, copy or picture
Perspective View → a live or real-time sighting or visual relationship
Both may function as Perspective Products, and both can convey information concerning the size, shape, position, orientation, depth, structure and appearance of spatial objects and scenes.
Perspective Image / View within Perspective Category Theory
Within Perspective Category Theory (PCT), an image or view is normally an outcome or product of one or more Perspective Processes.
The basic relationship can be expressed as:
Perspective Object / Scene → Perspective Process or System → Perspective Image / View
The complete analytical structure may include:
- Perspective Object / Scene — what the system is directed towards;
- Object or Target Space — the space containing that target;
- Perspective Category — the source or mode of the process;
- Perspective Class — the direction in which the process operates;
- Perspective Method or Type — the particular means employed;
- Perspective Process — the operation that occurs;
- Perspective Image / View — the resulting visual outcome;
- Perspective Form — the visual, optical, geometrical or spatial appearance produced.
The image or view should therefore be distinguished from the processes responsible for forming it.
What is a Perspective Image?
A Perspective Image is a visual representation of a spatial object or scene formed by a Perspective Method, System or Instrument.
It exists within Image Space or Perspective Space and may be located on or within a picture surface, optical system, medium of representation or other image-forming environment.
A Perspective Image may be:
- one-dimensional;
- two-dimensional;
- three-dimensional;
- real;
- virtual;
- optical;
- graphical;
- photographic;
- instrument-generated;
- simulated; or
- digital.
The essential feature is that the image represents, transforms or presents spatial information relating to an object, scene or other visual target.
What is a Perspective View?
In its primary sense, a Perspective View is a live or real-time visual or optical view of a spatial object or scene.
The view may be:
- seen directly by the human eye;
- formed optically on the retina;
- captured in real time by a camera;
- formed by another optical instrument; or
- presented through a real-time image or display system.
A Perspective View therefore emphasises the act or condition of viewing, rather than only the existence of a fixed representation.
In simple terms:
Image = visual representation
View = visual sighting or appearance from a viewpoint
Perspective Image and Perspective View compared
Volume 1 makes a useful distinction between a fixed Perspective Image and a live Perspective View.
A drawing or photograph may remain unchanged after it has been produced and can therefore be treated as a fixed Perspective Image.
A direct view of a room, landscape or object changes as the observer moves, turns, approaches, withdraws or changes direction of sight. This constitutes a Perspective View.
The distinction may be summarised as:
Perspective Image → fixed or recorded representation
Perspective View → live or real-time aspect
However, the terms have also been used more broadly and historically, so their intended sense should always be identified from context.
Primary Perspective View
A Primary Perspective View is the natural or live real-time view obtained while directly viewing spatial reality.
It may arise through:
- Visual Perspective Type 2;
- direct human vision;
- camera viewing;
- optical instruments; or
- other real-time imaging processes.
The defining feature is that the view relates directly to the spatial reality presently being viewed or imaged.
The Perspective Object / Scene remains directly available to the viewing or imaging system.
Secondary Perspective View
A Secondary Perspective View occurs when the observer views a representation of spatial reality rather than the original object or scene directly.
Examples include viewing:
- a drawing;
- a painting;
- a photograph;
- a recorded film;
- a digital image; or
- another represented Perspective Image.
The relationship therefore becomes:
Original Object / Scene → Perspective Image → Secondary Perspective View
This distinction is important because viewing the original spatial reality and viewing a representation of that reality constitute different stages in the complete perspective chain.
A broader use of the term Perspective View
The Dictionary records several meanings of Perspective View.
Three principal senses are distinguished:
- Natural Perspective View — a live or real-time optical view of a spatial object or scene;
- Perspective Representation — the representation on a plane surface of the appearance of spatial objects according to optical and mathematical principles;
- Vue d’optique or Graphical Perspective View — a print, drawing, painting, etching or graphical construction designed to produce or enhance a strong impression of spatial depth.
The term view can therefore refer either to an actual act of viewing or, historically and graphically, to a represented view.
Perspective Image as a representation in Image Space
A Perspective Image represents a spatial object or scene within Image Space.
This can be expressed as:
Object Space → Perspective Process → Image Space
The image may correspond to the Object Space while nevertheless transforming some of its properties.
For example:
- three-dimensional depth may become represented on a two-dimensional surface;
- equal-sized objects may project to different image sizes;
- parallel spatial lines may appear to converge;
- circles may project as ellipses;
- planes may become foreshortened;
- objects may overlap and conceal one another; and
- spatial relationships may be compressed, expanded or distorted.
The Perspective Image is therefore a transformed spatial representation rather than simply a duplicate of the original target.
Captured Perspective Images
A Captured Perspective Image is formed in the image-forming or Viewing or Imaging Class.
The general direction is:
spatial reality → image-forming system → Perspective Image
Captured Perspective Images can include images formed or represented through:
- the eye;
- lenses;
- cameras;
- telescopes;
- other optical instruments;
- drawings;
- paintings;
- computer graphics;
- mathematical modelling; and
- computer ray tracing.
The resulting image may be two-dimensional or three-dimensional and may represent a physical, simulated or modelled spatial reality.
Projected Perspective Images
A Projected Perspective Image belongs to the forward or Projecting Class.
Here an image, light beam, shadow or related visual form is projected forwards into spatial reality.
The basic relationship is:
image or source → projection → physical, optical or simulated space
Examples identified in the Dictionary include:
- cinema projection;
- light beams;
- cast shadows;
- holographic images;
- Virtual Reality;
- Augmented Reality; and
- Mixed Reality systems.
The projected image may visually modify, overlay or become integrated with the spatial environment onto or into which it is projected.
The two directional classes of Perspective Image
The distinction between Captured and Projected Perspective Images corresponds to the two fundamental Perspective Classes.
Viewing or Imaging Class:
Object / Scene → Image
Projecting Class:
Image / Source → Spatial Reality
A complex system may use both directions.
A camera-projector arrangement, for example, may first capture a Perspective Image and then project that image onto another surface or spatial environment.
Perspective Image and Perspective Form
A Perspective Image is the visual product or representation, while its Perspective Form concerns the particular visual, optical, geometrical or spatial appearance produced.
Perspective Form may involve changes in:
- apparent size;
- shape;
- position;
- orientation;
- line convergence;
- curvature;
- depth;
- colour;
- clarity;
- contrast; or
- illumination.
The distinction can therefore be expressed as:
Perspective Image → the visual product
Perspective Form → the appearance displayed by that product
Geometrical and Optical Facets of a Perspective Image
The Dictionary distinguishes geometrical and optical facets of Perspective Images.
A geometrical facet concerns the transformed geometry of the image or view, including features such as:
- line directions;
- vanishing points;
- horizon or vanishing lines;
- shape;
- position;
- scale; and
- overall projection geometry.
An optical facet concerns characteristics associated with light, including changes in colour, intensity and contrast.
A single Perspective Image may therefore possess several interacting geometrical and optical characteristics.
Viewpoint and the Perspective Image / View
A Perspective Image or View is normally related to one or more viewpoints.
Changing the viewpoint can alter:
- which surfaces of an object are visible;
- apparent size;
- apparent shape;
- occlusion;
- foreshortening;
- line direction;
- relative spatial position; and
- the overall Perspective Form.
The same Perspective Object / Scene can therefore generate many different Perspective Images and Views.
The object may remain unchanged while the visual result changes according to viewpoint.
Field of View and View Angle
The appearance of a Perspective Image / View may also depend upon its view angle and field of view.
The Dictionary identifies relevant optical characteristics including:
- viewpoint;
- view angle;
- field of view;
- aspect of view;
- optical depth;
- projection scale;
- projection-scale resolution;
- magnification factor; and
- geometrical and optical image facets.
These characteristics help determine how much of the spatial target is represented and how its different regions appear within Image Space.
Perspective Image / View and Visual Perspective
Visual Perspective Type 1 encompasses direct and represented visible appearances, views and images.
Visual Perspective Type 2 concerns the human retinal and perceptual subclass within Visual Perspective Type 1.
A represented Perspective Image may therefore exist independently as a drawing, photograph or digital image, while its subsequent viewing by a human observer introduces the retinal and perceptual processes of Visual Perspective Type 2.
In a simplified chain:
Perspective Image → human viewing → Visual Perspective Type 2
The represented image and the observer’s resulting visual experience should therefore not automatically be treated as the same thing.
Perspective Image / View as a Perspective Product
Images and views are among the principal Products of Perspective.
Perspective processes may produce:
- an image;
- a view;
- a measurement;
- a calculation;
- a representation;
- a model; or
- another spatial appearance.
A Perspective Image / View can therefore function both as an end product and as a source of further spatial information.
It may reveal or assist in determining properties such as object location, size, shape, orientation, arrangement, texture, colour and other aspects of spatial reality.
An Image can become the target of another process
A Perspective Image does not necessarily terminate the perspective chain.
It can become the target of another Perspective Process.
For example:
physical scene → camera → photograph → digital processing → display → human viewing
The photograph is initially the Product of the camera process, but it subsequently becomes an input or target for digital processing and display.
One system’s Image Space may therefore become another system’s Object or Target Space.
This is especially important in photography, cinema, television, digital imaging and New Media Perspective.
Images and Views can be Composite
A final Perspective Image or View may result from several Perspective Categories operating sequentially or in combination.
For example:
Natural scene → Optical and Instrument imaging → New Media processing → display → Visual Perspective Type 2
The finished image or viewed result may therefore constitute Composite Perspective.
The visible image should not automatically be attributed to only one Perspective Category simply because it appears to be a single image.
One Image can contain several Views
A Perspective Image need not contain only one simple or homogeneous view.
Perspective systems can combine, overlay, blend or juxtapose multiple views.
Examples include:
- Combined Perspective;
- Blended Perspective;
- Manifold Perspective;
- multi-view imagery;
- mirror reflections;
- transparent overlays; and
- digital compositing.
The distinction between image and view is useful here because one resulting image may contain, combine or present several different views or spatial relationships.
Real and Virtual Perspective Images
The Dictionary recognises both real and virtual Perspective Images.
A real image may be formed where light physically converges or is recorded on an image surface or sensor.
A virtual image may appear to occupy a spatial location from which the light does not actually originate in the corresponding manner.
Mirror images provide a familiar example of virtual Image Space.
The concept of Perspective Image must therefore be broad enough to include both physically formed and optically apparent image locations.
Perspective Representation
A long-established use of Perspective View concerns graphical representation on a plane surface.
In the classical perspective-window model, a spatial object is viewed through a notional or actual transparent picture plane and its visible outlines are transferred to that surface.
The relationship can be represented as:
spatial object → viewpoint and visual rays → picture plane → perspective representation
The resulting graphical image becomes a fixed Perspective Image representing the appearance of the spatial object from the selected viewpoint.
The Perspective Image / View as a spatial substitute
A represented Perspective Image can operate as a visual substitute for an absent object or scene.
It can preserve enough relationships for the viewer to recognise, interpret, measure or otherwise understand aspects of the original spatial target.
However, correspondence is normally partial rather than complete.
A Perspective Image may lose or transform:
- depth information;
- actual scale;
- hidden surfaces;
- some spatial relationships;
- fine detail; or
- other properties of the original scene.
The image should therefore not be confused with the spatial reality it represents.
Why Perspective Image / View matters
The distinction between Perspective Image and Perspective View clarifies one of the most basic ambiguities in perspective terminology.
It helps distinguish:
- a fixed representation from a live view;
- the original object or scene from its visual outcome;
- Object Space from Image Space;
- the Perspective Process from the Product it produces;
- captured images from projected images;
- primary direct viewing from secondary viewing of representations;
- the Perspective Image from its Perspective Form; and
- one visual product from the longer image chain through which it is produced and viewed.
Perspective Image / View therefore identifies the visual outcomes through which spatial objects, scenes and represented realities are imaged, viewed or presented: principally as fixed Perspective Images or as live and real-time Perspective Views, while recognising the broader historical and graphical uses of both terms.
Related Perspective Topics
Perspective Object / Scene →
Object Space →
Image Space →
Perspective Process →
Perspective Product →
Perspective Form →