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Viewing cone

Viewing cone is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Viewing cone rather than just read about it. In short: The viewing cone is the set of effective viewing directions of a visual display, as seen from the eye. This collection of angles resembles a generalized cone.

Viewing cone — main illustration
Viewing cone — illustration

Key takeaways

  • Viewing cone belongs to science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Viewing cone to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Viewing cone from memory before moving on to harder problems.

Reference excerpt

The viewing cone is the set of effective viewing directions of a visual display, as seen from the eye. This collection of angles resembles a generalized cone. The concept has been introduced as an international standard ISO 13406-2, which defines it as the range of viewing directions that can safely be used for the intended task without "reduced visual performance". This standard describes a complex procedure which evaluates the viewing cone from measurements of luminance and chromaticity versus direction of observation. ISO 13406-2 introduces 4 viewing direction range classes, from a wide viewing cone, for many simultaneous observers, to the so-called "privacy display", with a severely limited viewing cone. Compliance routes for different display applications can now be found in the successor standard ISO 9241-300.

Viewing direction

When a visual display with non-vanishing size is seen by an observer, every point of the display area is seen from a different direction as illustrated in fig. 1. No two spots on the display are seen from the same direction. The larger the display is and the closer the observer is to the display the more the viewing direction varies over the surface area of the display. Colloquially, the viewing direction is often called "viewing angle". This is an ill-chosen expression which should be avoided, because the viewing direction is specified by two polar angles: the angle of inclination, θ (measured from the surface normal of the display) and the azimuth angle, Φ, measured in the plane of the display as shown in figure 3.

In fig. 2, the eyeball represents the observer that is looking at a specific spot on the display which is identical to the origin of the polar coordinate system. The green arrow is the viewing direction (i.e. direction of observation). The viewing direction is specified by the angle of inclination, θ, measured from the surface normal of the display (blue vertical arrow) while the azimuth angle, Φ, is the angle that the projection of the viewing direction onto the surface of the display makes with the x-axis (red arrow). The projection of the viewing direction is shown here as the shadow of the green arrow. The azimuth angle Φ increases counterclockwise as illustrated in figure 3.

The multitude of directions, from which a display can be seen without artifacts and distortions that would render its intended use impossible (e.g. computerized office work, television, entertainment) is called the viewing cone (even though its shape might be that of a generalized cone).

… excerpt ends here. Continue reading the full article.

Illustrations

Viewing cone: Figure 2: Illustration of an example of a viewing cone centered about the surface-normal of the display. The viewing cone may be tilted and rotated and may be of a less regular shape.
Figure 2: Illustration of an example of a viewing cone centered about the surface-normal of the display. The viewing cone may be tilted and rotated and may be of a less regular shape.
Viewing cone: Figure 3: Illustration of the specification of the viewing direction by two polar angles: the angle of inclination (measured from the surface normal of the display) and the azimuth angle, measured in the plane of the display
Figure 3: Illustration of the specification of the viewing direction by two polar angles: the angle of inclination (measured from the surface normal of the display) and the azimuth angle, measured in the plane of the display
Viewing cone: Figure 4: Illustration of the specification of the range of viewing directions (aka viewing cone) in a polar coordinate system. The pseudo-colors represent the value of a physical quantity (e.g. luminance) for each viewing direction.
Figure 4: Illustration of the specification of the range of viewing directions (aka viewing cone) in a polar coordinate system. The pseudo-colors represent the value of a physical quantity (e.g. luminance) for each viewing direction.
Viewing cone: Figure 5: Luminance and contrast versus viewing direction in a polar coordinate system. The left column shows the directional luminance distribution of the dark state of the display (IPS LCD), the center column shows the bright state and the right column shows the (luminance) contrast (ratio) resulting from the preceding two luminance distributions. The value is coded by (pseudo) colors. The graphs below the polar coordinate systems each show a cross section in the horizontal plane and indicate the values for luminance and for the contrast. Each borderline between two (shades of) colors represents a line of constant value, in the case of contrast an iso-contrast (contour) line.
Figure 5: Luminance and contrast versus viewing direction in a polar coordinate system. The left column shows the directional luminance distribution of the dark state of the display (IPS LCD), the center column shows the bright state and the right column shows the (luminance) contrast (ratio) resulting from the preceding two luminance distributions. The value is coded by (pseudo) colors. The graphs below the polar coordinate systems each show a cross section in the horizontal plane and indicate the values for luminance and for the contrast. Each borderline between two (shades of) colors represents a line of constant value, in the case of contrast an iso-contrast (contour) line.

Worked examples

Example 1 — a first encounter with Viewing cone

Start with the simplest possible case. Write down what Viewing cone claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Viewing cone before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Viewing cone ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Viewing cone

In research
Viewing cone appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Viewing cone in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Viewing cone is common in secondary-school and first-year university syllabi. It links to neighbouring topics Display technology, Liquid crystal displays, so understanding it makes those chapters shorter.
In everyday life
Look for Viewing cone outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Viewing cone in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Viewing cone means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Viewing cone out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Viewing cone in simple terms?

The viewing cone is the set of effective viewing directions of a visual display, as seen from the eye. This collection of angles resembles a generalized cone.

Why does Viewing cone matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Viewing cone?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Viewing cone.

Tags

  • Display technology
  • Liquid crystal displays

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