Eyes: A User Manual

A practical guide to using the eyes to see spatial reality in perspective—and to interpreting drawings, photographs, paintings, films and other perspective images accordingly.

We use perspective continuously. Every time we look across a room, judge the distance of an object, recognise a Form from an oblique angle, navigate through a building, look into a photograph or interpret a drawing, the visual system is extracting spatial information from perspective.

Yet most people are taught almost nothing about how to use their own eyes to understand perspective.

This page provides a practical introduction to seeing in perspective: what the eyes receive, how viewpoint and eye movement affect appearance, which visual phenomena provide information about depth and Form, and how the same principles can be used to interpret perspective images.

Human vision should not be treated simply as a camera. The eye forms an optical image, but seeing also involves retinal processing, eye movement, binocular coordination, bodily orientation, memory, expectation and perceptual interpretation. Understanding perspective therefore requires us to distinguish between Physical Form, optical appearance, retinal information and perceived visual space.

Seeing Is a Perspective Process

Seeing does not transfer physical reality unchanged into the mind. Spatial reality gives rise to optical information; the eyes form retinal images from that information; and the visual system organises and interprets these changing images as objects, surfaces, directions, distances and spatial relationships.

Within the PRC framework, Visual Perspective Type 2 concerns perspective as formed and experienced through the human or animal visual system.

The first rule of this user manual is therefore:

What we see is not physical geometry itself. We see a viewpoint-dependent appearance from which the visual system attempts to understand physical geometry.

This distinction is fundamental to perspective. A rectangular surface may appear trapezoidal, a distant object may appear small, and parallel lines extending through depth may appear to converge—without the Physical Forms themselves changing.

The Eye as an Optical Instrument

The eye is a sophisticated biological optical system. Light entering the eye first passes through the cornea, then through the pupil whose diameter is controlled by the iris, before being refracted by the crystalline lens and brought to focus upon the retina.

The retina contains light-sensitive receptor cells that convert the incoming optical pattern into neural signals. These signals are then transmitted and processed through the visual system.

The retinal image is inverted relative to the external scene. For geometrical purposes, the eye can be approximated as a central projection system in which rays from object points are directed towards a centre of projection and then form corresponding retinal image points.

However, this analogy has limits. The retina is curved rather than flat; receptor density is highly non-uniform; the eyes move continuously; two eyes normally contribute information; and the resulting retinal signals undergo extensive neural and perceptual processing.

The human eye is therefore camera-like in some optical respects, but human vision is not simply a camera.

The Viewpoint Comes First

Every ordinary perspective view begins from a location.

For a stationary eye, this can be represented by the eye point, viewpoint or station point: the position from which a spatial scene is observed. In geometrical perspective it can be treated approximately as the centre of projection.

Change the viewpoint and the perspective changes.

  • Move sideways and overlapping relationships change.
  • Move forwards and visual angles increase.
  • Move backwards and visual angles decrease.
  • Raise or lower the eye and relationships to eye level and the horizon change.
  • Move around an object and different surfaces become visible.
  • Change the viewing direction and a different aspect of the scene is presented.

When analysing either physical reality or a perspective image, therefore ask:

  • Where is the observer?
  • How high is the eye point?
  • How far is the observer from the subject?
  • In which direction is the observer looking?
  • Is the viewpoint stationary or moving?

These questions often reveal more about an image than immediately searching for vanishing points.

Direction of Vision and Field of View

Two ideas that are frequently confused should be kept separate.

Direction of vision concerns where the observer is looking. It can be represented by a Sight Line, line of sight, visual axis or principal viewing direction extending outward from the eye.

Field of view concerns the angular extent of the surrounding scene visible around that direction.

The observer may therefore remain at the same station point while changing the viewing direction. Likewise, the observer may fixate one point while remaining aware of a much wider surrounding field.

In perspective theory, distinguishing the central viewing direction from the total angular field is essential. A central Sight Line is not the whole field of vision.

Central and Peripheral Vision

Human vision is not uniformly detailed across the whole visual field.

The region surrounding the point of fixation provides the greatest visual acuity. Away from this central area, resolving power progressively decreases, although peripheral vision remains extremely important for detecting movement, large-scale Form, orientation, contrast and changes in illumination.

With the eyes and head fixed, the combined human visual field extends approximately 200° horizontally, although measured limits vary. The central binocular overlap is approximately 120°.

For one eye, the field extends approximately 100° towards the temporal side, around 60° towards the nose, approximately 60° upwards and about 75–80° downwards, depending upon the observer and method of measurement.

This is important because the human visual field is considerably wider than the conventional 30–60° cone of vision frequently recommended in rectilinear perspective drawing. That restricted graphical cone is primarily a practical means of reducing conspicuous lateral stretching or distortion on a flat rectilinear image. It is not the total field of normal human sight.

Try It

Look directly at one word on this page. Without moving your eyes, notice how much surrounding material remains visible. Then attempt to read a word far from the fixation point without looking directly at it.

You can detect material across a broad field, but detailed examination requires directing central vision towards it.

This loss of detail away from fixation is specifically related to visual acuity and retinal eccentricity. It should not be confused with optical defocus or with the loss of contrast and colour caused by Atmospheric Perspective.

Clarity, Acuity, Focus and Atmospheric Perspective

Visible clarity does not vary for one reason alone. Several different perspective and optical processes can reduce the amount of detail that an observer can see, and these should not be confused.

It is useful to distinguish Acuity Perspective, Diminution of Form, focus and Depth of Field / Depth of Focus, and Atmospheric Perspective.

Acuity Perspective / Perspective of Visual Acuity

The retina does not provide equal resolving power across the whole visual field. Visual acuity is greatest at and close to the point of fixation and falls progressively with increasing angular distance from it.

An object viewed peripherally may therefore appear less distinct than the same object examined directly, even though its physical distance has not changed.

This belongs to Acuity Perspective, also related to Perspective of Visual Acuity, Clarity Perspective and Detail Perspective.

The effect is principally related to retinal position and angular eccentricity from the point of fixation, rather than to the physical distance of the object alone.

This is one reason the eyes continually move: objects requiring detailed inspection are brought towards the high-acuity central region of vision.

Diminution of Form and Visible Detail

A different effect occurs when an object recedes from the observer. As distance increases, its apparent or angular size decreases. Progressively smaller structural features and outline irregularities may eventually fall below the resolving capacity of the eye.

This contributes to Diminution of Form: the progressive loss of visible outline structure and fine detail with increasing distance, decreasing image scale or insufficient resolution.

A distant tree, for example, may retain a recognisable overall Form while individual leaves, twigs and smaller irregularities cease to be separately visible.

The loss of visible detail therefore results partly from the relationship between apparent angular size and visual resolution. It does not mean that distance automatically makes an object optically defocussed.

Focus and Depth of Field

A separate source of reduced clarity is focus or defocus.

The eye changes optical focus through accommodation. Objects at, or sufficiently close to, the accommodated distance can appear sharply focussed, while objects sufficiently in front of or behind that range may become increasingly defocussed.

Depth of Field refers to the range of object-space distances—from nearer to farther objects—that appear acceptably sharp for a particular optical arrangement.

For normal viewing of spatial reality, Depth of Field is therefore the directly relevant term for the range of object distances appearing sufficiently in focus.

Depth of Focus

Depth of Focus is related but technically different. It concerns the allowable image-space region behind the lens within which the receiving surface can be positioned while retaining acceptable image sharpness.

Depth of Field and Depth of Focus should therefore not be treated as synonyms:

Depth of Field = object-space range of acceptable sharpness.
Depth of Focus = image-space tolerance behind the lens.

Focus and defocus may themselves provide useful depth information, particularly at closer viewing distances.

Atmospheric Perspective

At larger distances another quite different process becomes increasingly important: Atmospheric Perspective, also known as Aerial Perspective.

Light travelling from distant objects passes through an increasing quantity of atmosphere. Scattering, absorption, haze, moisture and suspended particles can progressively reduce contrast, clarity, colour saturation and visible detail.

Distant hills, for example, may appear lower in contrast, less saturated and less sharply differentiated from their surroundings than nearer hills. Their apparent hue may also shift towards the prevailing colour of the intervening atmosphere.

This reduction of clarity is therefore not primarily caused by retinal eccentricity or optical defocus. It is an environmental optical effect occurring between the object and the observer.

Four Different Reasons Why Detail May Disappear

  • Acuity Perspective: the object lies away from the point of fixation and is sampled by a lower-acuity part of the visual field.
  • Diminution of Form: increasing distance reduces apparent angular size until finer structural details fall below visual resolution.
  • Focus / Depth of Field: the object lies sufficiently outside the currently focussed range to produce optical defocus.
  • Atmospheric Perspective: intervening atmosphere reduces contrast, colour distinction, clarity and visible detail.

Several of these processes can operate simultaneously. A distant object may subtend a small visual angle, contain detail below the observer’s resolving limit and also be partially obscured by atmospheric haze.

Correct perspective analysis therefore requires us to identify which process is changing the visible information, rather than referring generally to a loss of clarity.

The Eyes Move

A fixed-eye diagram is useful for geometrical analysis, but real human vision rarely remains fixed.

The eyes make continuous movements to inspect different parts of the visual environment. The head turns. The body rotates. The observer walks towards, away from and around objects.

Every significant change in eye position or viewing direction produces new perspective information. Apparent outlines change, relative sizes alter, occlusions shift and parallax relationships become visible.

Yet the external environment normally appears comparatively stable rather than jumping around whenever the eyes move.

This leads to an important distinction between the visual field and the visual world.

The visual field is associated with a particular fixation and orientation. The visual world is the comparatively stable, extended three-dimensional environment perceived across changing views.

Human visual experience is therefore not a single instantaneous perspective snapshot. It is built and continuously updated across time.

Use One Eye: Monocular Perspective

Close one eye and look around.

The world does not suddenly become flat.

This elementary experiment demonstrates an extremely important fact: binocular stereopsis is not necessary for the perception of extensive three-dimensional space.

A single eye retains access to many powerful sources of spatial information, including:

  • Diminution of Size;
  • Aspect of Form;
  • foreshortening;
  • line convergence and vanishing;
  • occlusion and superposition;
  • height or position in the visual field;
  • texture gradients;
  • relative and known size;
  • motion parallax;
  • focus and defocus;
  • Depth of Field;
  • illumination and shading;
  • surface and contour information;
  • Atmospheric Perspective;
  • loss of visible detail and Diminution of Form.

This is also why a physically flat photograph, drawing, painting, cinema screen or computer display can create such a powerful impression of spatial depth.

The represented image may contain no physical depth at all, yet the visual system can interpret its perspective phenomena as evidence of a three-dimensional scene.

Use Both Eyes: Binocular Perspective

Now hold one finger fairly close to your face against a distant background. Close first one eye and then the other.

The finger appears to shift position relative to the background because the two eyes occupy different locations and therefore receive slightly different perspective views.

This positional difference is binocular disparity, also described in perspective contexts as binocular or stereoscopic parallax. The visual system uses these differences to assist the perception of relative depth.

The eyes also turn inward when fixating a nearby object. This vergence or convergence supplies additional oculomotor information related to viewing distance.

Binocular stereopsis is particularly effective for fine relative-depth judgements at close range. Its effectiveness decreases rapidly as viewing distance increases because the angular differences between the two eye views become progressively smaller.

For rooms, streets, landscapes, architecture and other larger or more distant scenes, monocular perspective information therefore remains critically important.

The Retinal Image Is Not Visual Space

One of the most important distinctions in visual perspective is between the retinal image and the visual space that is ultimately perceived.

The retinal image is an optical pattern formed upon the light-sensitive retinal surface.

Visual space is the experienced organisation of apparent:

  • direction;
  • position;
  • distance;
  • depth;
  • size;
  • shape;
  • orientation;
  • movement.

The two are related, but they are not identical.

Likewise, the retinal image should not be equated with the stable visual world that we experience around us. Seeing involves the interpretation and integration of optical information across two eyes, changing fixation points and continuing movements of the eyes, head and body.

A Retinal Direction Does Not Give Distance

This is a fundamental limitation of any single visual projection.

Light arriving from a particular direction stimulates a corresponding location within the retinal image. But that direction alone does not tell the eye the absolute distance of the object from which the light originated.

Many different object points lying along approximately the same visual direction could theoretically produce stimulation at the same retinal location.

Depth must therefore be inferred from additional spatial information.

The visual system combines perspective phenomena, binocular disparity, vergence, movement, focus, context, known Forms and previous experience to establish the most probable spatial interpretation.

Perspective is consequently not merely an optical projection problem. It is also a decoding and interpretation problem.

The Visual Reference Framework

To understand a perspective view, the observer also needs a framework for direction and orientation.

Several visual references can assist this process, including:

  • the eye or station point;
  • the Sight Line or principal viewing direction;
  • eye level;
  • horizontal and vertical directions;
  • the ground or supporting plane;
  • the Horizon Plane and horizon;
  • body-centred or egocentric axes;
  • external reference lines and planes;
  • the Visual Element of the System or directional reference used by the particular perspective arrangement.

These references help the observer register what is seen relative to gravity, the body, the environment and the perspective system itself.

Visual orientation therefore involves more than determining where something falls on the retina. The visual system must continually relate retinal information to eye position, head orientation, body orientation, gravitational information and the surrounding environment.

Learn to Read Perspective Phenomena

To see perspective more consciously, stop looking only for named objects and start noticing the changes in appearance produced by viewing them.

Diminution of Size

Equal or comparable objects generally subtend smaller visual angles as their distance from the viewpoint increases. A row of identical posts, windows or paving slabs therefore appears progressively smaller as it recedes.

Aspect of Form

The apparent shape of an object changes as its orientation relative to the viewpoint changes. A circular disc viewed frontally appears circular; turned obliquely, its projected appearance becomes increasingly compressed.

Foreshortening

Spatial dimensions that extend substantially into depth appear shortened in projection. Foreshortening may therefore carry information about both orientation and recession.

Convergence and Vanishing

Parallel spatial directions extending through depth may appear to converge towards vanishing positions. Railway tracks and the edges of a long corridor are familiar examples.

Occlusion and Superposition

If one object partially hides another, the occluding object is normally interpreted as being nearer. Occlusion is one of the strongest monocular indicators of relative depth order.

Texture and Repetition

Repeated surface elements—tiles, bricks, windows, trees, road markings and paving—form gradients that can reveal surface recession, orientation and scale.

Diminution of Form

As apparent angular size decreases, fine outline structure and small surface features become progressively harder to resolve. The object may therefore retain its general Form while losing visible detail.

Atmospheric Perspective

With increasing distance, intervening atmosphere may reduce contrast, clarity and colour saturation and shift apparent colour. This forms a powerful natural indicator of spatial recession.

Motion Parallax

When the observer moves, nearby objects generally change visual direction more rapidly than distant objects. This differential motion provides powerful information about depth.

These phenomena seldom operate entirely alone. Human vision combines multiple sources of information to construct a probable spatial interpretation.

Physical Form and Apparent Form

A rectangular table does not physically become trapezoidal when viewed obliquely.

A distant person does not physically become miniature.

Parallel railway tracks do not physically meet at the horizon.

Perspective therefore requires a clear distinction between the Physical Form of an object and the Apparent Form produced from a particular viewpoint.

The Physical Form belongs to object space. The Apparent Form is the visible perspective appearance resulting from the relevant viewing, imaging or projection process.

Visual interpretation therefore often works in the reverse direction:

Apparent Form → inferred spatial structure → probable Physical Form

But this reconstruction is not necessarily unique. More than one physical arrangement can sometimes generate the same or a very similar visible appearance.

This is one aspect of the wider Correspondence / Equivalence Problem of perspective.

Seeing Requires Assumptions

A perspective image never contains all the information present in the original spatial reality.

A single view cannot normally reveal the hidden rear surface of an opaque object. Occluded structures disappear. Physical depth is projected into an image relationship. Absolute scale may be unknown. The original viewpoint may be uncertain. Lens, projection, processing and display characteristics may further transform the resulting image.

The visual system therefore supplements the available image information with assumptions derived from experience.

These can include assumptions about:

  • known object size;
  • probable Physical Form;
  • gravity;
  • vertical and horizontal directions;
  • parallelism;
  • right angles;
  • symmetry;
  • surface continuity;
  • lighting;
  • occlusion;
  • the likely viewpoint;
  • the likely imaging or projection system.

The observer is therefore an active participant in perspective interpretation—the beholder’s share is part of the decoding process.

Look for Structural Order

One of the most effective ways of interpreting a complicated visual scene is to search for its simplest underlying Forms.

Humans readily recognise:

  • points and straight lines;
  • planes;
  • parallel and perpendicular relationships;
  • circles and ellipses;
  • squares and rectangles;
  • regular solids;
  • symmetry;
  • repetition;
  • grids and frameworks.

Perspective then transforms these regular structures into recognisable apparent patterns.

A tiled floor becomes a perspective grid. A row of identical windows becomes a diminution sequence. Parallel building edges establish spatial directions. A wheel viewed obliquely reveals Aspect of Form. Repeated columns reveal depth and recession.

When a scene appears complicated, first look for the simplest underlying structural Forms.

This is one reason architecture and built environments are especially useful for studying perspective: they contain large quantities of visible geometrical order.

If the View Is Ambiguous, Move

A single perspective view may not contain sufficient information to identify the original spatial arrangement unambiguously.

The most natural solution is often to obtain another view.

Move the head slightly from side to side. Step forwards. Walk around the object. Look from above or below.

Movement generates new information through:

  • motion parallax;
  • changing occlusions;
  • changing apparent size;
  • changing Aspect of Form;
  • changing surface visibility;
  • changing line directions;
  • changing binocular relationships;
  • views of previously hidden structures.

A static image can remain ambiguous. A sequence of changing perspective views can reveal the three-dimensional arrangement much more clearly.

Looking Around and Looking At

Two complementary visual operations are especially important in understanding how people explore spatial reality.

Sphere of Vision — Looking Around

Remain at approximately one station point while changing the viewing direction to inspect the surrounding environment.

Conceptually, all possible viewing directions can be organised around a Sphere of Vision centred upon the observer.

Sphere of Revolution — Looking At

Instead of remaining at one station point, move around an object and inspect it from different viewpoints.

Conceptually, this produces a Sphere of Revolution around the object of attention.

The distinction can be summarised simply:

Sphere of Vision = viewpoint broadly fixed; viewing direction changes.

Sphere of Revolution = object broadly fixed; viewpoint changes.

Ordinary human seeing constantly uses limited versions of both operations.

Inside and Outside the Image

Another useful distinction concerns whether the observer is effectively inside or outside the space being explored.

In natural vision, we are immersed within physical object space. We can look in different directions, move through the environment and continually generate new perspective views.

A conventional photograph or painting is different. The viewer normally remains outside a bounded image surface and looks into a represented space from a comparatively restricted position.

Panoramic, dome, stereoscopic, Virtual Reality and Augmented Reality systems progressively alter this relationship by increasing field, changing image geometry or allowing the viewer to navigate within the represented environment.

The degree of freedom available to the viewer is therefore a useful way of distinguishing perspective systems.

Interpreting a Perspective Image

A photograph, painting, film frame or digital image may have passed through several perspective processes before finally reaching the eyes.

A simplified photographic image chain might be:

physical scene → camera optics → sensor → image processing → stored image → display → eye → retina → visual perception

A CGI image has a different chain. A cinema image adds projection and screen geometry. A stereoscopic display produces separate images for the two eyes. Virtual Reality may add stereo rendering, head tracking and dynamically changing viewpoints.

Every stage can preserve, remove, distort, transform or construct spatial information.

When interpreting an unfamiliar perspective image, therefore ask:

  • What is the original target or object space?
  • Is that target physical, represented, imaginary or simulated?
  • What process first formed or captured the image?
  • What projection geometry was used?
  • Has the image subsequently been transformed?
  • What display geometry am I now viewing?
  • Where was the original station point?
  • What information has been preserved?
  • What information has been lost?
  • What information may have been artificially constructed?

Understanding the image therefore means reconstructing, as far as possible, the perspective image chain.

Viewing Distance Matters

A perspective image is not entirely independent of the position from which it is viewed.

A classical central-perspective construction corresponds to a particular station point and viewing geometry. Viewing the image from a substantially different distance or lateral position changes the visual angles subtended at the eye.

However, the frequently repeated claim that every perspective picture must always be viewed from one exact original station point is too simple.

If the image has been enlarged or reduced, the corresponding geometrical viewing distance changes proportionally. Reproductions in books, on websites and on screens may therefore require different physical viewing distances from the originals.

Human perception also makes considerable allowances for image scale and viewing conditions. We routinely understand photographs, drawings, paintings and films even when we are not located at their theoretically exact construction points.

Nevertheless, extreme viewing positions can make perspective discrepancies increasingly conspicuous.

Beware of Wide-Angle Rectilinear Images

A flat rectilinear perspective image can preserve straight projected lines while simultaneously producing substantial lateral stretching towards its edges when a very wide angular field is represented.

This should not automatically be equated with ordinary human peripheral vision.

The human visual system combines a very wide overall field with moving eyes, high central acuity, reduced peripheral acuity and continual perceptual integration.

A wide-angle photograph instead places a large angular field into one fixed rectangular image.

Objects close to the edges of such photographs can consequently appear strongly stretched even though the image remains geometrically consistent with its chosen rectilinear projection.

This distinction is fundamental when comparing natural vision with photographic or graphical perspective.

A Practical Method for Reading Any Perspective Image

1. Identify the Target Reality

Is the image directed towards physical reality, an imaginary scene, a model, a simulation or some combination?

2. Locate the Viewpoint

Estimate the position, height, distance and direction of the observer or imager.

3. Identify Recognisable Forms

Look for planes, rectangles, circles, cylinders, grids, parallel lines, repeated intervals and familiar objects.

4. Identify the Perspective Phenomena

Look for diminution, aspect change, foreshortening, convergence, vanishing, occlusion, texture gradients, Atmospheric Perspective, focus and defocus, parallax and loss of detail.

5. Identify the Perspective System

Could the image be a natural view, linear perspective drawing, photograph, wide-angle view, parallel projection, panorama, stereoscopic image, CGI rendering, mirror view, VR image or another form?

6. Separate Evidence from Assumption

Which spatial relationships are visibly present, and which are being inferred from familiarity, gravity, known scale, symmetry or previous experience?

7. Consider Alternative Interpretations

Could another Physical Form or spatial arrangement produce the same Apparent Form?

8. Seek Another View

If the interpretation remains ambiguous, movement or another image may provide the missing information.

Five Simple Experiments

1. One Eye / Two Eyes

Look across a room with one eye closed. Notice that the room still appears strongly three-dimensional. Then hold a finger close to your face and alternate between the two eyes to reveal binocular parallax.

2. Apparent Form

Hold a circular object facing directly towards you and slowly rotate it. The Physical Form remains circular while the Apparent Form becomes progressively compressed.

3. Diminution and Detail

Find a row of similar windows, paving slabs, lights, columns or fence posts extending through depth. Compare both their progressively changing angular sizes and the loss of fine detail as they recede.

4. Motion Parallax

Fixate a distant object and move the head gently from side to side. Nearby objects appear to shift much more rapidly relative to the distant background.

5. Acuity and Fixation

Fixate one object while attending to another object some distance away in the peripheral field. Then look directly at the second object. Its physical distance has not changed, but much finer detail becomes available when it moves into central vision.

The Essential Rules

  • Perspective begins with a viewpoint.
  • Direction of vision is not the same as field of view.
  • Physical Form and Apparent Form are not identical.
  • A single retinal direction does not specify absolute distance.
  • Depth is interpreted from multiple sources of spatial information.
  • Monocular perspective cues provide a powerful perception of 3-D.
  • Binocular disparity and vergence add particularly useful information at closer ranges.
  • Central vision is highly detailed; peripheral vision is much broader but less acute.
  • Acuity Perspective, Diminution of Form, optical defocus and Atmospheric Perspective are different causes of reduced visible detail.
  • Depth of Field concerns object-space sharpness; Depth of Focus concerns image-space tolerance.
  • The eyes, head and body continually move.
  • The momentary visual field is not the same as the stable visual world.
  • The retinal image is not identical to perceived visual space.
  • The human visual field should not be confused with the conventional graphical cone of vision.
  • Perspective images inevitably omit some information about their target reality.
  • The observer contributes prior knowledge and assumptions while interpreting an image.
  • Movement and multiple viewpoints can resolve ambiguities that a single image cannot.
  • The appearance of an image depends upon the complete perspective system that produced and displays it.

Learn to See Perspective

To become better at perspective, do not merely learn how to draw vanishing lines. Learn how to look.

Observe how objects change with distance and direction. Compare one-eyed and two-eyed vision. Notice what happens when you move. Separate Physical Form from Apparent Form. Look for repeated structures, changing aspect, vanishing relationships, occlusions, texture gradients, Atmospheric Perspective, changing focus, motion parallax and changes in visible detail.

Above all, ask what information an image actually contains—and what information your visual system has inferred.

The eyes are extraordinarily capable perspective instruments, but retinal image formation is only the beginning. Seeing spatial reality involves optics, geometry, physiology, movement and perception working together.

Understanding these processes makes it possible not only to see perspective more clearly, but also to interpret photographs, paintings, drawings, films, digital images and other representations with considerably greater precision.

Related Pages

Continue with these closely related Perspective Research Centre pages:

For the fuller theoretical treatment of these subjects, see The Art and Science of Perspective, Volume 1: The Past, Present and Future of Visual and Optical Perspective and the Dictionary of Perspective, Second Edition.