Information design:
in practice, an informed theory

InformForm is an international platform for information design, which celebrates and explores both practical and theoretical experimentation within the field of design. It prides itself on showcasing relevant examples of work by students, for students. Read More

The technical glossary is an opportunity to become familiar with a range of charts, technical terms and visualisation methods that can aid experimentation and trigger further research.

Glossary definitions viewed as a grid list

In this section we begin to compare apples with oranges, literally and figuratively. It’s an opportunity to become familiar with a range of charts, technical terms and visualisation methods that can aid experimentation and trigger further research.

We recommend using this section of InformForm with a sense of purpose and your ideas in hand. Visualisations can be static, interactive or animated and the medium can have a big impact on the creative process.

  • Area and Volume Charts

    Use plane shapes and solids to communicate differences in data units within a dataset. This section explains principles of use and how to calculate area and volume of various figures.

    • Area: Circle

      Area: Circle

      Construct circles proportional to specific data units using the formulae below.

      First, calculate Radius = R:
      Then, calculate Diameter = D:

      D = R + R

      You can also find circle calculators online. The example above shows circles representing A=20 and B=10 proportionally.

    • Area: Equilateral Triangle

      Area: Equilateral Triangle

      Construct equilateral triangles according to specific data units using the formula below.

      Calculate side length M:
      You can also find equilateral triangle calculators online. The example above shows equilateral triangles representing A=20 and B=10 proportionally.

    • Area: Rectangle

      Area: Rectangle

      Construct rectangles according to specific data units using the formulae below. You need to have your data unit and one side length of the rectangle M or N. The example above shows rectangles representing A=20 and B=10 proportionally.

      To calculate side length M:
      So, for a data unit of 20, if N = 5, then M = 4.

      To calculate side length N:
      You can also use rectangle calculators online.

    • Area: Square

      Area: Square

      Construct squares according to specific data units using the formula below.

      Calculate side length M:
      You can also find square calculators online. The example above shows squares representing A=20 and B=10 proportionally.

    • Meaning of Shapes

      Meaning of Shapes

      Specific meanings, some culturally-based, are contained within polygons, circles and solids. When deciding which types of shapes should be used to convey data, the designer must be aware of any meaning(s) already associated to them and chose one that is appropriate to the data, and that does not cause confusion or create double meaning of information.

    • Placement: Layout and Alignment

      Placement: Layout and Alignment

      Once the data units are translated into figures, grouping them correctly will allow for clear comparisons and direct relationships to be made. Placement and layout of figures must be considered from the very start of the project.

    • Placement: Scaling Circles

      Placement: Scaling Circles

      Scaling circles show the distribution of data on a map or diagram. The centre of the circle usually aligns with the location it relates to.

    • Placement: Splitting

      Placement: Splitting

      With splitting, area or volume charts are linked to points on a diagram or map. Area/volume charts can also be linked to other elements for contrast and comparison, for example, two trees produce more apples than one. However, this tends to unnecessarily repeat information and should be avoided.

    • Principles of Area and Volume Charts

      Principles of Area and Volume Charts

      Each figure represents one data unit; the data unit defines the area of the polygon or circle, or the volume of the solid. For accurate visual comparison, only one type of shape should be used for one category within a chart, for example, population variation in different cities, represented by circles. When put together, the data units, are shown proportionally and in relation to one another, as a set of similar shapes.

      Always decrease or increase the size of shapes within a set simultaneously, in order to keep the proportions accurate between the data units. Never adjust individual items in order, for example “to fit the page”. If there are huge discrepancies between the data units, and the polygons, circles or solids they represent, those differences are an integral part of the dataset and the designer must find an editorial solution to represent them.

      It is often difficult to accurately measure values using area and volume charts, therefore actual values are generally included with the polygon, circle or solid it represents.

      Area and volume charts are comparison and relationship tools, that work best when two or more data units are represented, in order to communicate the relative sizes between them.

    • Volume: Cone

      Volume: Cone

      Construct cones according to specific data units using the formulae below. You can calculate either radius (R) or height (H).

      Calculate Radius = R, when given data unit (Volume) and height H:
      Calculate Height = H, when given data unit (Volume) and radius R:
      You can also use cone calculators online. The example above shows cones representing A=20 and B=10 proportionally.

    • Volume: Cube

      Volume: Cube

      Construct cubes according to specific data units using the formula below.

      To calculate side length M:
      You can also find cube calculators online. The example above shows cubes representing A=20 and B=10 proportionally.

    • Volume: Rectangular Prism

      Volume: Rectangular Prism

      Construct rectangular prisms according to specific data units using the formulae below.

      Calculate Height = H, when given data unit (volume) and one side length M or N:
      You can also use calculators for rectangular prisms online. The example above shows rectangular prisms representing A=20 and B=10 proportionally.


    • Volume: Right Cylinder

      Volume: Right Cylinder

      Construct right cylinders according to specific data units using the formulae below. You can calculate either radius (R) or height (H).

      Calculate Radius = R, when given data unit (Volume) and height H:
      Calculate Height = H, when given data unit (Volume) and radius R:
      You can also find cylinder calculators online. The example above shows right cylinders representing A=20 and B=10 proportionally.

    • Volume: Right Square Pyramid

      Volume: Right Square Pyramid

      Construct pyramids according to specific data units using the formulae below. You can calculate either square base side (M) or height (H).

      Calculate square base side M, when given data unit (Volume) and height H:
      Calculate Height = H, when given data unit (Volume) and square base side M:
      You can also find right square pyramid calculators online. The example above shows right square pyramids representing A=20 and B=10 proportionally.

    • Volume: Sphere

      Volume: Sphere

      Construct spheres according to specific data units using the formulae below.

      First, calculate Radius = R:
      Then, calculate Diameter = D:

      D = R × 2

      You can also find sphere calculators online. The example above shows spheres representing A=20 and B=10 proportionally.

  • Flat Figures and Solids

    Knowledge of basic geometry can help you express values and make comparisons of data. This section explains how to calculate the area, perimeter and volume of various figures.

    • Angle: Acute

      Angle: Acute

      An acute angle is an angle smaller than 90°.

    • Angle: Obtuse

      Angle: Obtuse

      An obtuse angle is an angle with more than 90° and less than 180°.

    • Angle: Right

      Angle: Right

      A right angle is an angle equal to 90°.

    • Area = A

      Area = A

      The extent of a polygon. It can be expressed in any unit of measurement (cm, feet, or other). Always measured in square units. See Square Number entry in the Notes section.

    • Circle


      A circle is a two dimensional shape bounded by a circumference. Any point in the circumference is at the same distance from the centre.

      D = diameter
      R = radius

      To calculate Area = A:
      You can also use circle calculators online to solve area, diameter and circumference.

    • Circle: Sector and Segment

      Circle: Sector and Segment

      A wedge-shaped area of a circle is called a sector. A portion of a circle whose lower boundary is a chord and whose upper boundary is an arc is called a segment.

      E = sector
      G = segment
      R = radius
      π = pi
      θ = theta = angle encompassing E or G

      Find the Area = A of a sector E:
      So, if θ = 60°, and R = 10, then A = 52.3.

      In order to find the Area = A of a segment G, you must first find the area of the sector using the formula above. Then, find the area of the triangle with the formula:
      And finally, subtract the area of the sector with the area of the triangle:
      You can also use sector and segment calculators online.



    • Cone


      A cone is a solid with a curved side from its flat base (often circular) to a point called the apex or vertex. The vertex of a right cone is above the center of its base.

      R = radius
      H = height
      π = pi

      To calculate Volume = V:
      You can also use cone calculators online to solve, volume, height, radius, surface and base area.

    • Cube


      A cube is a regular hexahedron bounded by six square faces or sides.

      M = side length

      To calculate Volume = V:
      So, if M = 10 then V = 1000.

      You can also use cube calculators online to solve volume, space diagonal and edge.


    • Cylinder


      A cylinder is a solid with two circular surfaces and its ends.

      R = radius
      H = height
      π = pi

      To calculate Volume = V:Adata-cylinderNEW
      You can also use cylinder calculators online to solve volume, surface and base area.

    • Ellipse


      An ellipse has two perpendicular axes, minor and major, that intersect at the centre of the ellipse. Half of the minor and major axes are R1 = minor radius and R2 = major radius respectively.

      To calculate Area = A:
      You can also use ellipse calculators online to solve area and circumference.

    • Parallelogram


      A parallelogram is a quadrilateral with parallel opposite sides and equal opposite angles.

      M = side length
      H = height

      To calculate Area = A:

      A = M × H

      You can also use parallelogram calculators online to solve area, perimeter and side lengths.

    • Perimeter = P

      Perimeter = P

      The sum of the lengths of all sides of a polygon.

    • Polygon


      Polygons are two-dimensional figures made up of three or more closed line segments. Each line segment of a polygon is a side, and polygons are classified by the number of sides.

    • Pyramid


      A pyramid is a solid whose outer surfaces are triangular and converge to a single point at the top. The base can be trilateral, quadrilateral, or any other polygon shape.

      M N = base sides
      H = height

      To calculate Volume = V of a quadrilateral pyramid:
      So, if M N = 10 and H = 13, then V = 433.33.

      You can also use online pyramid calculators to solve volume, surface area, base area and pyramid height.

    • Rectangle


      A rectangle is a quadrilateral with four right angles. Opposite sides are parallel and of equal length.

      M = short side
      N = long side

      To calculate Area = A:

      A = M × N

      You can also use rectangle calculators online to solve area, diagonal and perimeter.

    • Rectangular Prism

      Rectangular Prism

      A rectangular prism is a solid with at least 4 faces that are rectangles.

      M = width
      N = depth
      H = height

      To calculate Volume = V:
      You can also use rectangular prism calculators online to solve, volume, surface area and space diagonal.

    • Right Triangle

      Right Triangle

      A right triangle is a triangle in which one angle is a right angle, that is, a 90° angle. The sides of a right triangle are:

      M = adjacent leg
      N = hypotenuse
      O= opposite leg

      To calculate Area = A:
      You can also use right angled triangle calculators online to solve area, perimeter and hypotenuse.

    • Solid


      Solids are three-dimensional figures. Some solids have curved and/or flat surfaces, some have polygons as faces. Solids are classified by the type and number of faces.

    • Sphere


      A sphere is a perfectly round geometrical solid. Any point in the surface of a sphere is at the same distance from the centre.

      D = diameter
      R = radius

      To calculate Volume = V:


      So, if R = 10, then:


      You can also use online sphere calculators to solve volume, diameter and surface area.


    • Square


      A square is a regular quadrilateral with four equal sides and four right angles, that is, 90° angles.

      M = side length

      To calculate Area = A:
      You can also use square calculators online to solve area, perimeter, side and diagonal.

    • Trapezoid


      A trapezoid or trapezium in the US, is a 4-sided flat shape with straight but no parallel sides.

      M N = side lengths
      H = height

      To calculate Area = A:
      You can also use trapezoid calculators online to solve area, perimeter and side lengths.

    • Triangle


      A triangle is any polygon with three edges (line segments) and three vertices (corners or intersections).

      M = base length
      H = height

      To calculate Area = A:
      You can also use triangle calculators online to solve area, perimeter and side lengths.

    • Triangle: Equilateral

      Triangle: Equilateral

      An equilateral triangle has three equal sides, and all three internal angles are each 60°.

    • Triangle: Isosceles

      Triangle: Isosceles

      An isosceles triangle has two equal sides and two equal internal angles.

    • Triangle: Scalene

      Triangle: Scalene

      A scalene triangle has no equal sides or angles.

    • Volume = V

      Volume = V

      Measure of the amount of space inside a three-dimensional figure. Volume is expressed in cubit units.

  • Relationship, Hierarchy and Time Charts

    This section looks at relationships, hierarchies, movements and flows, and time structures. Their aim is to cluster and present degrees of similarity between items, time and location.

    • Arc Diagram

      Arc Diagram

      Arc diagrams visualise connections between location, time or any other categories. Arcs connect nodes (N) along the axis, cross-referencing information and depicting patterns of distribution, activity, flow and movement, as well as finding co-occurrences within the data.

      Colour, symbol or text can be used. Arcs can have one or several stroke thicknesses, the latter denoting amount — the fatter they are, the greater the amount they represent. Arc diagrams can be arranged vertically or horizontally.

      Arc diagrams can be problematic when too many connections make the diagram hard to read.

      Check out D3 demos on how to generate arc diagrams.

    • Chord Diagram

      Chord Diagram

      Chord diagrams, radial network diagrams or radial convergence diagrams, visualise how different entities, variables and/or frequencies connect, interact and relate to one another. The data is arranged around a circle with connections drawn as arcs attaching similar or comparable elements within the dataset.

      Data can be grouped into different categories (A B C), and colour is often used to distinguish the groups. The stroke thickness of arcs can be proportional to the value they represent.

      Chord diagrams are visually attractive but can easily become illegible with too many connecting arcs. Grouping lines together, called hierarchical edge bundling (example on the right), can sometimes help to reduce visual clutter.

      Circos and D3 are some of the software tools available for visualising chord diagrams and other circular diagrams.

    • Family Tree

      Family Tree

      A family tree is essentially a tree diagram. See Tree Diagram entry.

      Family trees show family relations and descent. Symbols can be introduced to represent marriage/union, adoption, female/male, or other.

    • Genogram


      A genogram visualises relationships among individuals of a family as well as hereditary medical patterns and psychological considerations. Genograms make use of colour and symbols to differentiate relationships and personal circumstances.

      A basic genogram structure and symbols include: the male parent is at the left and the female parent is at the right of the family. Male is represented by a square, female by a circle. A family is shown by an horizontal line connecting the two. Children are placed below the family line from the oldest to the youngest, left to right. In the example above, the hostile relationship is shown with a zig-zag line, and diabetes with a coloured segment.

    • Parallel Set Chart

      Parallel Set Chart

      Parallel sets visualise flow, proportions and distribution of categorical data at different levels (L). The width of the flow lines is proportional to the value they represent.

      Colour and transparencies can be used to compare and differentiate the distribution between different categories. Both vertical (top to bottom) or horizontal (left to right) arrangements can be accommodated.

      The example above shows distributed data across 3 levels of categories:
      L1: C = Cats and D = Dogs
      L2: F = Female or M = Male
      L3: W = Wild or D = Domesticated

      Check Eagereyes and D3 for demos and software on how to generate parallel sets.

    • Sankey Diagram

      Sankey Diagram

      Sankey diagrams depict directions and transfers of movements and flows within a quantitative system. Direction is indicated by arrows and can be enhanced by other symbols. The width of the flow lines is proportional to the value they represent, so the thicker the line, the larger the quantity of the flow.

      Colour can be used to divide the diagram into different categories or to show transitions within the flow.

      Sankey diagrams can be used in conjunction with maps or timelines.

      Check libraries such as Sankey Diagram Software and Tamc to help you generate sankey diagrams.

    • Sunburst Tree

      Sunburst Tree

      The sunburst tree is essentially a tree diagram, that uses a radial rather than a linear layout to depict relationships and hierarchies of information. See Tree Diagram entry for more information.

      The core of the hierarchy is at the centre (A) with deeper levels farther away from it (B C etc). Colour is often used to distinguish different attributes within the data. It requires two or more hierarchical levels.

      Check mbostock and Raw for coding and libraries on how to generate sunburst diagrams.

    • Tree Diagram

      Tree Diagram

      Tree diagrams, also known as organisational charts and genealogical or family trees, visualise hierarchies of information in a tree-like structure.

      Typically, the tree diagram starts with one or two entries. These subdivide into multiple branches (B), as many as necessary. The point where a branch subdivides into more branches is referred to as a node (N). The end-nodes are members who have no child nodes. The branches of the tree represent the relationships and connections between the members and can also depict categories, degrees of similarity between items, clusters, time and/or location (L).

      Tree diagrams can have horizontal or vertical arrangements or can be circular. See Sunburst Tree entry for circular tree diagrams.

      To generate a tree diagram you must first count the number of nodes, branches and levels your data needs. Plot all the data in a rough matrix and once this is done, start building the grid that will accommodate all the variables and branches.

  • Sector Charts and Graphs

    A sector is a portion of a circle, usually in the shape of a ‘slice’. Sector charts and graphs represent percentages, cycles or changes over time.

    • Donut Pie Chart

      Donut Pie Chart

      A doughnut or donut pie chart is a pie chart with a blank centre. See Pie Chart entry for construction techniques.

      The benefits of using a donut pie chart over a pie chart is that the latter focuses on comparing the proportions between slices, whilst the first focuses the attention on the length of the arcs, hence allowing for a more accurate reading. Extra information can be included in the centre of the chart.

    • Pie Chart

      Pie Chart

      A pie chart consists of a circle divided into proportional slices. Each slice represents one data unit, and the entire circle represents the sum of all the data units within the dataset, equal to 100%. Pie charts show the proportional sizes of data units to one another and to the whole and can be arranged in any order, although smallest to largest clockwise is often used. Actual values, percentages, or both may be used to support the chart. It is not advisable to use pie charts to represent large datasets.

      The pie chart above is composed of 3 data units: A = 1, B = 6 and C = 3, the sum of all A B C = 10.

      To calculate percentages for each data unit:
      (A, B or C × 100) : ABC = A%, B% or C%
      A% = (1 × 100) : 10 = 10%
      B% = (6 × 100) : 10 = 60% and
      C% = (3 × 100) : 10 = 30%
      the sum of all = A B C = 100%

      To calculate the angle of each slice:
      (A%, B% or C% × 360) : 100 = Aº, Bº or Cº
      Aº = (10 × 360) : 100 = 36º
      Bº = (60 × 360) : 100 = 216º and
      Cº = (30 × 360) : 100 = 108º
      the sum of all = A B C = 360º

    • Polar Area Diagram

      Polar Area Diagram

      See Rose Diagram entry.

    • Rose Diagram

      Rose Diagram

      A rose diagram, also polar area diagram, is a circular graph divided into slices of equal angles that extend from the centre at different lengths. How far each slice extends depends on their data unit value. Concentric rings determine the quantitative scale and three or more data units should be used.

      The rose diagram is used to plot observable cyclic data, for example, amount of rain per month over a 6-month period. Here, there will be 6 slices, A B C D E and F (one per month), all with the same angle of 60 degrees each.

    • Stacked Rose Diagram

      Stacked Rose Diagram

      A variation of the rose diagram. See Rose Diagram entry. Here, several categories or types of information (Type 1 and Type 2) can be stacked in one slice allowing for comparison of various variables over time.

      The example above could depict, for example, both the amount of rain and damage caused per month over a 6-month period. Six slices, A B C D E and F (one per month), all with the same angle of 60 degrees each.

  • Bar/Column Graphs and Histograms

    Bar/column graphs display categorical data and histograms depict continuos data over an interval. This section explains principles and types of bar/column graphs and histograms.

    • Axes and Scales

      Axes and Scales

      For bar/column graphs or histograms, the unit, percentage or frequency scale runs parallel to the bars/columns length (D) and the lowest value usually sits in the intersection of D and E. Categories (graphs) or sequence of intervals (histograms) are placed along the base line axis (E). Negative as well as positive values can be plotted.

    • Bar and Column

      Bar and Column

      ‘Bar’ refers to an horizontal arrangement, left to right or right to left, and ‘column’ refers to a vertical one, up or down.

    • Bar/Column Graph

      Bar/Column Graph

      Bar/column graphs are used to compare data units within categories or data entities (A B C). One axis of the chart consists of the categories or data entities, and the other axis represents the numerical scale.

    • Composite Graph

      Composite Graph

      Composite bar/column graphs are used to show how one category or data entity divides itself into smaller data units. Multiple segment values are placed after each other vertically or horizontally. The total of each bar or column is the total for that category.

    • Display of Bars/Columns

      Display of Bars/Columns

      Bars/columns of a bar/column graph can be joined or separated. On an histogram, spaces between bars/columns are usually eliminated.

    • Grouped or Clustered Graph

      Grouped or Clustered Graph

      Grouped or clustered bar/column graphs are used to compare grouped categories or data entities.

      Two or more datasets are grouped together, plotted side-by-side and aligned on the same axis. Each group of bars/columns should be spaced apart from each other, and each dataset should be assigned a colour or shade to distinguish it from other sets.

    • Histogram


      Histograms are data distribution graphs that show the frequency with which continuous or discrete data occurs within intervals. See Continuous and Discrete Numbers entry in Notes. Percentage values can also be included.

      Each bar/column in an histogram represents the number of data units in each class interval, therefore, the total area of the histogram is equal to the total number of data units in a dataset.

      The example above shows 1 data unit in the interval 1 to 2.5; 3 in the interval 2.5 to 4; and 2 between 4 to 5.5.

    • Number of Bars/Columns

      Number of Bars/Columns

      A minimum of 2 bars/columns is a requirement. There is no maximum number of bars/columns, however, labelling can become an issue when there is a large amount of bars/columns.

    • Overlapped Graph

      Overlapped Graph

      A variation of the grouped or clustered bar/column graph. Here, bars or columns are partially or fully overlapped aligned on the same axis. The downside of this version is that data units may be hard to contrast and compare.

    • Percentage Composite Graph

      Percentage Composite Graph

      Composite bar/column graphs are used to show how one category or data entity divides itself into smaller data units. Percentage composite graphs show the percentage of the whole of each group. Multiple segment values are placed after each other vertically or horizontally, and the sum of each group must be 100%.

    • Population Pyramid

      Population Pyramid

      A population pyramid is a type of two-way histogram that looks for population distribution patterns, for both sexes (A B), and in all age groups. It can be used to identify differences and changes in population patterns over time and/or space. Multiple population pyramids can be used to compare patterns across population groups or nations.

      The age axis of a population pyramid can be displayed as intervals or single years for greater detail. The age axis can be placed between the sexes or outside. Female and male are plotted side by side on the vertical axis, often aligned to the centre.

    • Three-dimensional Graph

      Three-dimensional Graph

      When the axes, scales, bars or columns are in perspective. Construct a three-dimensional grid for the bars/columns as well as the quantitative scale. The grid can take any form and depends on the shape you wish the bars/columns to take. The downside of this variation is that information may be hard to contrast and compare.

    • Two-way Bar/Column Graph

      Two-way Bar/Column Graph

      A variation of the bar/column graph. Here, two datasets are plotted side by side to compare variations and correlations of similar categories or data entities.

    • Width of Bars/Columns

      Width of Bars/Columns

      There is no specific rule for the width of the bars and columns, except for area bar/column graphs. The width of bars/columns should remain uniform throughout one graph.

  • Area Graphs

    Area graphs display quantitative data with filled areas or simply as a line graph. This section explains basic construction principles and types of area and line graphs.

    • Area Graph Principles

      Area Graph Principles

      Area graphs illustrate positive and negative trends, relationships and changes over time. Typically, they are stepped, segmented or curved and are most frequently used to depict category and sequence. Area graphs can be interpreted by reading the values on the axes or through polygon comparison.

    • Axes and Scales

      Axes and Scales

      Area graphs are usually arranged horizontally with sequence, category or quantitative scale plotted on the horizontal axis, and a quantitative or percentage scale on the vertical axis. Both negative and positive values can be plotted.

    • Categorical Area Graph

      Categorical Area Graph

      Categorical area graphs compare data units within categories. All categories are plotted along the horizontal axis (A B C). Data units are then plotted directly above each category, in their corresponding quantitative value. The example above shows A = 1, B = 3 and C = 2.

    • Grouped Area Graph

      Grouped Area Graph

      In grouped area graphs all areas touch the horizontal axis, therefore, the top of each area depicts the actual values of the data series. Any overlapped areas must be visible by means of transparency, dotted lines, patterns or other.

    • Percent Stacked Area Graph

      Percent Stacked Area Graph

      A variation of the stacked area graph except each data series is depicted as a percent of the whole. See Stacked Area Graph entry.

    • Sequential Area Graph

      Sequential Area Graph

      Sequential area graphs depict the development of quantitative values for one data series or category over a period of time or interval. Reading is usually left to right, on an horizontal arrangement. Sequential area graphs are drawn by plotting the data units on a cartesian coordinate grid, and then filling the space below the line that joins the points. The example above shows changes over time for one category and the sequence of values plotted are 1.0, 2.1, 1.2 and 3.3.

    • Stacked Area Graph

      Stacked Area Graph

      Stacked area graphs show multiple data series placed after each other horizontally. Only the bottom data series extends to the horizontal axis and the entire graph represents the total of all the data plotted. Stacked area graphs work with both sequential and categorical scales.

    • Three-dimensional Area Graph

      Three-dimensional Area Graph

      When the axes, scales and areas are in perspective. The downside of this variation is that perspective often makes the graph hard to read.

  • Pictogram and Symbol: Construction Guidelines

    The following guidelines attempt to establish visual strategies to inform the design and construction of symbols and pictographic languages.

    • Baseline


      In typography, the baseline (B) is an invisible line where lower case letters ‘sit’ and below which descenders extend. In pictographic design, it is also possible to place objects on a baseline, suggesting a ridge for those objects to rest on. Just like in typography where rounded lowercase letters extend slightly below the baseline in order to achieve an optical effect of being the same size (O = overshoot), so do symbols need to have similar concerns. It is advisable to keep the baseline consistent across the entire pictographic system as this results in the uniform arrangement of objects.

    • Format


      The format of a symbol is often defined by the visible or invisible container. It allows for each symbol to stand alone without altering the legibility and meaning of other nearby symbols. The format should be used consistently throughout a system and should have a direct relationship with the grid. The example shows the container in yellow.

    • Grid Blanks for Practice

      Grid Blanks for Practice

      Once the grid is defined, it is useful to create blanks for practice. With pen/pencil and paper, explore the complexities, composition and alignments of symbols before moving to the screen.

    • Horizontal Spacing

      Horizontal Spacing

      Symbols require a system of consistent spacing much like words in a sentence. Spacing (S) can improve or interfere with the readability of a pictographic system. If the spacing between two symbols is too tight, meaning and content will run into each other. If space between symbols is too wide, the connection between them is less direct. Use the proportions of the grid to set the distances between containers. Consistent spacing width applies when using variable container widths.

    • Human Figure

      Human Figure

      Avoid using the standardised symbols for male, female, baby and wheelchair figures. These are associated with the ubiquitous and old-fashioned toilet signage and are often graceless and clunky. Always design your own in order to individualise your visual vocabulary.

      The example above shows a set of standardised ‘toilet’ symbols on the left, and ‘designed’ human symbols on the right.

    • Modular Grid

      Modular Grid

      Always use a grid when designing symbols and across visual languages. Creating a versatile grid that works for your design direction is key. The grid can be as simple or as complex as you need it to be, but it should always be used consistently to help create compositional uniformity. The grid is usually the last thing to be discarded.

      Symbols have modular properties when their construction is based on one or more modules influenced by the grid.

    • Optical Optimisation

      Optical Optimisation

      Once the grid is discarded, symbols can go through a stage of refinement; although the outcome corresponds to the grid, it may be optically conflicting. To attain improved visual balance and proportions, trust your visual intuition by applying minimal visual adaptations and refinement.

    • Pictographic Identity

      Pictographic Identity

      Uniformity, identity and visual rhythm within a pictographic system are accomplished through the consistent handling of dot, line, shape, surface and colour. It is the job of the designer to understand the needs for each symbol and system. Any visual and stylistic decisions will be influenced by details such as image complexity, relationship and distribution of objects within one symbol as well as size.

    • Safe Work Area

      Safe Work Area

      Like the printed page, the pictographic format requires a margin. The safe work area determines the maximum work area for the symbol. The margin between the symbol and the edge of the format is particularly relevant when working with visible containers. The object can be fully or partially exposed. Full objects are enclosed entirely inside the safe work area. Partial objects rely on context for interpretation as they represent a section of a larger object or theme, i.e. hand.

    • Simple Grid

      Simple Grid

      When using a minimal grid, visual unity of a pictographic system is achieved by the consistent use of a set of formal visual elements. Limit the number of visual elements, their sizes, composition and alignment features to enforce consistency across the system.

      The example above shows a set of graphic elements which combined create a set of individual symbols. Consistency is emphasised through the use of appropriate alignments and other visual identifiers such as colour, line, etc.

    • Size


      Symbols should be versatile and work in all required sizes, contexts and mediums, large and small. In principle, larger symbols can accommodate greater expressive detail while smaller representations require simplicity and schematisation. Whenever possible, test symbols at 1:1 scale. Always test how symbols respond to print, screen or any other media as appropriate.

    • Small Sizes and ‘Inktraps’

      Small Sizes and ‘Inktraps’

      Inktrap features are found in typefaces designed for printing onto newsprint in very small sizes. Similar principles can be applied when designing symbols for small applications. Corners or details of an image are reduced to allow for ink to spread into the removed area. Without this feature, excess ink gets trapped, ruining the sharp edges and legibility of the symbol. Inktraps should never be a last minute decision. They must be incorporated in the visual vocabulary from the very start.

      For typefaces designed with inktraps you may want to look into Matthew Carter’s Bell Centennial.

    • Standardisation of Formats

      Standardisation of Formats

      Some formats such as those used for traffic or safety signs, have been standardised to signify specific commands. Examine existing standardised shapes and colour relationships and how these can inform your design.

    • Variable Container Width

      Variable Container Width

      Depending on the content and size of a pictographic system, you may need to create a variable container width to accommodate wider or narrower symbols. Allowing for variations in container widths creates opportunities to be more efficient with the use of space as well as having greater relevance to the format of the symbol. A variable container width allows for dynamic structures and is of particular benefit for larger pictographic systems. Limit the number of widths available to enforce consistency across the system.

    • Vertical Spacing

      Vertical Spacing

      Vertical spacing between symbols should also be considered. As a rule of thumb, the minimum vertical spacing should be 1.5 to 2 times the width of horizontal spacing. Different rules apply when typography is introduced. See entries relating to typography.

    • Visible Container

      Visible Container

      A visible container should be considered as one of the consistent features of the visual vocabulary. This single element contributes equally to the distinguishable features of the pictographic system. It defines the form and helps to emphasise the system, but it should never draw attention away from the visual content that it carries. The format should be used consistently throughout the system and should have a direct relationship with the grid. The shape of containers can be regular or irregular. A regular shape refers to a polygon with symmetrical sides, and all its angles equal. An irregular shape is asymmetrical with different sides and angles. You might also want to refer to ‘standardisation of formats’.

  • Pictogram and Symbol: Setting the Pictographic Identity

    Uniformity, identity and visual rhythm within a pictographic system are accomplished through the consistent handling of dot, line, shape, surface and colour.

    • 1 + 1 = 3 or More

      1 + 1 = 3 or More

      Visual elements can be hierarchical, perceptual and three-dimensional. Putting shapes together and triggering their positive as well as negative areas can create interesting optical illusions. Josef Albers expands on the visual effects of ‘one plus one equals three or more’ providing simple examples of its fundamental principles. Whilst constructing symbols, be aware of the interactive properties of shapes.

      The example on the top left corner shows two crossed lines creating extra shapes, i.e. triangles, rectangles, etc. The one on the bottom left corner, shows two lines side by side creating an extra ‘width’ between them. The two examples on the right demonstrate the interactive optical properties of shapes.

    • Alignment


      The alignment of a symbol engages and directs the eye to an area of the composition whether it is centred, left or right aligned, vertical or horizontal. Using alignment as a consistent element across the entire system emphasises its intentional visual purpose. If text and symbol are combined, consider the relationship between the two. See p.56 for further information.

    • Attention to Detail

      Attention to Detail

      When constructing symbols, make sure that the combination of shapes doesn’t create loose ends or unnecessary features, which are often perceived as mistakes.

    • Colour


      Colour can create unity and further consistency to a system of symbols. Like shapes, colour acquires particular functional duties, and one should reason its application from the very early stages of the project.

      Colour can distinguish categories of messages as well as augment the meaning of the sign (i.e. red to convey danger in the western world). Always use colour consistently as an aid for differentiation between formal or conceptual categories of signs, and with particular care for context and cultural associations. Colour is also used to contrast or harmonise the sign with the environment either by making it stand out or blend in with the environment. Colour is sometimes standardised by official bodies (i.e. green associated with exit) or defined by existing branding guidelines.

      When constructing symbols, initially work with black only as this is the best way to unify the system. Cultural context highly influences the interpretation of a colour’s meaning.

    • Composition


      When constructing symbols and placing them in context, consider composition and layout arrangements carefully. Composition is the arrangement and placement of visual objects in a layout or working area.

    • Curve and Angle

      Curve and Angle

      Curves and angles are usually determined by the finished size of the symbol as well as the medium where it will be published. When devising the visual vocabulary, define preferred curves and safe angles. As any other visual element, limit the number of curves and angles available to enforce consistency across the system. As a rule of thumb, small angles and curves are less readable in smaller symbols.

    • Diagonal and Direction

      Diagonal and Direction

      A diagonal is a measure of tension as it defines vertical and horizontal formats by increasing its inclination to either the vertical or the horizontal. Direction and diagonals actively create dynamic compositions through dominant or less dominant, harmonious or inharmonious. Furthermore, the point of intersection of two diagonals determines the centre of the composition.

    • Dot


      The dot is the simplest and possibly the most important unit of visual communication. When used within a composition, it engages and directs the eye. When placed at the centre of a composition, a dot can gain static qualities. When off-centred, it shows motion and direction. A dot also points at a location (on a map) and when grouped it can signify quantities. Different size dots can also represent quantitative data such as area charts. The dot must be used with consideration so it doesn’t interfere with the functional meaning of similar shapes.

    • Gradation and Radiation

      Gradation and Radiation

      Gradation is a series of gradual repetitive changes that run in the same direction. Radiation refers to a gradual expansion from a centre.

    • Line


      Line weight within a symbol is usually determined by the finished size of the symbol as well as the medium where it will be published. Thin lines may not be sufficiently visible if the symbol is large; similarly, thick lines may obscure the symbol’s identity and make shapes difficult to recognise. Thin or thick lines also affect the negative space and perceived heaviness, dominance and darkness of the symbol and overall system. Choosing appropriate line thickness requires testing and experimentation in order to make appropriate visibility and image definition. Note that when reversed, line thickness appears optically different: black lines on a white background appear larger than white lines on a black background.

    • Line Corners and Endings

      Line Corners and Endings

      Line endings can be either rounded or squared off. Similarly, both outer and inner corners can also be rounded or square off.

    • Optical Centre

      Optical Centre

      Positioning an object at the centre of a composition creates both a static illusion as well as the impression that the object is sliding off the page. To offset this, force place the object slightly above the middle of the composition.

    • Positive and Negative

      Positive and Negative

      ‘Positive’ and ‘negative’ space in a composition refers to opposite principles such as light and dark, busy and idle, static and dynamic. Deciding on a greater variety of opposites creates shifts in density and contrasts of colour and movement.

    • Shape


      The term ‘shape’ usually refers to the basic geometric configuration of an object and its outer boundary or outline. The shape of a symbol is often defined by the grid or by the use of shape that allows for the construction of all required geometric configurations of the system. Shapes can be anything from a dot or a point, a line, a curve or angle, a plane, a plane figure, a solid figure and all their endless variations.

    • Symmetry and Asymmetry

      Symmetry and Asymmetry

      Symmetry refers to objects identically arranged/reflected on both sides of an axis. Asymmetry is the absence of symmetry. Symmetry and asymmetry considerations are of equal importance in the design of symbols as they can have important consequences for its system.

    • Texture


      Textures can be felt or seen and consist of similar visual elements organised in a structure and pattern. A texture can represent light, shade and shadows, difference in materials and effects, for example a 3D block effect or rough edges. Texture can also have ornamental qualities.

    • Transparency and Opacity

      Transparency and Opacity

      While an opaque object is visually impenetrable, a transparent one allows light to shine through making elements behind it visible.

  • Pictogram and Symbol: Typography

    Pictographic and typographic considerations require simplicity, legibility and concision and should be considered in unison from the very beginning of the design process.

    • Aligning Text with Symbol

      Aligning Text with Symbol

      When combining textual and pictographic elements experiment with the word position in relation to the symbol and width of the text box. Consider the necessary integration or separation. If the word is positioned below the symbol and the word exceeds the width of the symbol, consider extra space on both sides to accommodate longer words.

      When listing all possible symbols at the beginning of a project, also note down supportive text. Test the text, object placement and size relationship opportunities during the early stages of symbol construction. Of equal importance is the spacing between symbols with text. See vertical spacing and horizontal spacing entries.

    • Alignment


      Left-aligned text is usually preferred for signage however when dealing with symbol and text, the alignment of text requires experimentation with the medium and context in mind. Text in a box is usually aligned using the x-height centred in the box. The width between ascenders and descenders can also define the centre alignment of the text. When using mostly uppercase, aligning the text based on the uppercase width can also be a suitable option.

    • Alphanumerical


      Using an alphanumeric system creates a flexible, logical and efficient way to navigate through spaces. Groups of letters and numbers indicate different categories such as for example an area of a building and the floor level. When there are more than two groups of letters and numbers, they should be separated by punctuation marks (point, slash, dash, etc). Letters of numbers assigned to floors change from country to country, region to region. In the UK, the letter G stands for ‘ground floor’, in Portugal R/C for ‘rés-do-chão'; other countries simply use the number 0. Coding floors below ground floor can be made by adding a minus symbol before each number or with alphanumeric coding such as B1 for the first level below ground, B standing for basement. In other instances, letters signify other areas such as M for mezzanine or P for parking.

    • Arrows


      In today’s context, graphic representations of arrows indicate action, progression or movement, and are generally understood as a directional device. As a metaphor of fast-moving arrow heads from the days of hunting, the symbol for the arrow should always be interpreted within the relevant context; whether it communicates direction in signage, supports other symbols or typographic messages. There are cases where the symbol for arrow is a separate symbol from the typeface it supports, however making the arrow a family member of the chosen typeface is desirable.

      Always consider the number of positions and variations of one arrow, and when supporting other symbols or text group them under one arrow only. The size of an arrow can be calculated as the distance between the descenders and ascenders of the same typeface. The arrow usually aligns with the height of the uppercase letters or x-height line. Arrows can have an open or closed head.

    • Ascenders and Descenders

      Ascenders and Descenders

      An ascender is the portion of a lowercase letter that extends above the x-height. A descender is the portion of a lowercase letter that extends below the baseline. The length of ascenders and descenders is an important consideration in the pictographic context. Long ascenders/descenders might take too much vertical space whilst too short ones might affect legibility. Finding a good balance between the two is recommended.

    • Direction of Reading

      Direction of Reading

      In the West, text is normally written horizontally, top to bottom, left to right. However, other directions are often considered too. When vertically, letters can be placed horizontally under each other; as a general rule this should be done with upper-case letters only. A line of text (lower and uppercase words) can also be rotated 90 degrees to the left to be read from the bottom up; or 90 degrees to the right to be read from the top down.

      Context plays an important part in which option to use: for example, in the West books tend to use the latter option (top down reading), as this is the natural direction of western reading. For signage, some people prefer the first option (bottom up) as the reading begins lower, closer to eye level. Always consider the context and test your options before making a final decision.

    • Historical and Cultural Considerations

      Historical and Cultural Considerations

      When choosing a typeface consider the historical or cultural associations related to its form and its subsequent impact to the content and context. The examples above show Futura, a modernist geometric sans-serif typeface designed in 1927 by Paul Renner, and Georgia, a serif typeface designed by Matthew Carter in 1993 specifically for computer screen even at small sizes.

      Key texts:
      The Elements of Typographic Style by Robert Bringhurst
      The Geometry of Type: The Anatomy of 100 Essential Typefaces by Stephen Coles.

    • Identity


      Whether the pictographic system design is based on a typeface in brand guidelines, or needs to be designed in conjunction with a system, or a system needs to be matched with a typeface, symbol and type should be read as part of the same family, and this relationship will inform the overall identity.

    • Italics


      Refer to true italics rather than oblique. A true italic (also cursive) is a specifically drawn style, which takes its shape from a stylised form of handwriting. An oblique italic is the roman font—usually without any structural difference—slanted at an angle to appear italic.

    • Leading and Line Spacing

      Leading and Line Spacing

      When text is placed above or underneath the symbol an appropriate vertical distance between the baseline of text and the top edge of the bottom container, or bottom edge of the top container must to be considered. Line spacing should be generous to separate messages and support legibility, making very clear that the text labelling one container is not labelling another instead. Leading should be compact when line lengths are short. The number of lines and words appearing on one sign should be reduced to a minimum. As a rule of thumb the space between two baselines is 2–2.5 times x-height.

      Spacing principles apply when calculating vertical distances symbol to symbol and text to symbol.

    • Letter and Word Spacing

      Letter and Word Spacing

      Letter and word spacing is the degree of decrease or increase of space between letters and words in a body of text. Once main copy or paragraphs are set, further typographic refinement can be done via tracking and kerning. Tracking adjusts letter spacing uniformly over a range of characters or words while kerning adjusts letter spacing between selected pairs of letters.

      Character combinations such as an uppercase and a lowercase letter usually need kerning. As a general rule, all uppercase words need to be tracked as they otherwise appear too tight or irregular spaced. Equally, numbers usually need to be kerned, in particular character combinations with zeros and ones. Make sure the word is legible and readable, achieving a visually pleasing result. For maximum legibility, letter and word spacing in signage often are slightly larger than for print. As a rule of thumb, word spacing of a typeface should be half its x-height.

      Key texts:
      Using Type by Michael Harkins
      Detail in Typography by Jost Hochuli
      A Type Primer by John Kane
      Unjustified Texts: Perspectives on Typography by Robin Kinross
      The Stroke: Theory of Writing by Gerrit Noordzij

    • Lowercase and Uppercase

      Lowercase and Uppercase

      Usually, a combination of upper and lowercase text is more readable than text written in uppercase letters only. Signs that use capitalised text such as STOP, WARNING, do so to emphasise authority. With the advent of digital communication, capital letters became associated with ‘shouting’ or angry responses. Always consider your context.

    • Medium


      Typeface selection should be informed by the medium. Screen typography creates new challenges and opportunities for the designer accustomed to a print workflow. Typefaces designed specifically for screen use have been tweaked by the designer for optimal readability and legibility. Verdana & Georgia (among the most widely viewed screen fonts), share similar characteristics, notably the proportionally large x-height. This ensures increased legibility of individual characters whilst occupying the same screen estate.

      The widespread adoption of web typography, and the abundance digital type services such as Typekit, means that digital designers no longer have to restrict their designs to a few ‘web safe’ fonts. Many web fonts are now digitally hinted to optimise their display at varying sizes. Gone are the days of screen fonts designed using a rigid grid of pixels.

      The same rules around typographic hierarchy apply equally to screen as they do in print, only now, we must pay more attention to context. Today’s multi-device web means we can no longer control how a user is consuming our content, but we can take steps to mitigate the risks, and provide an optimal experience. CSS media queries allow us to define specific ‘break points’, enabling us to apply style rules based on the size of a user’s screen. Newer CSS properties such as ‘vw’ and ‘vh’ allow us to scale type directly in proportion to screen width, and a variety of tools and frameworks exist to aid grid layout and typographic harmony, see Gridset and Modular Scale.

      Accessibility considerations remain important. It is essential that any web fonts use relative sizing, enabling the user to scale up the text size at will. A generous line height, text ragged left, and sufficient contrast between foreground and background colours are also important considerations. See Jonathan Snook’s Colour Contrast Check tool.

      Above an example of typographic hinting of Palatino italic based on an illustration by Douglas E. Zongker.

      For more information on screen typefaces see Verdana and Georgia by Matthew Carter or Pellucida by Chuck Bigelow.

    • Multilingual, Multi-script and Braille

      Multilingual, Multi-script and Braille

      In a globalised world, signage is aimed at the widest possible audience. For this reason, multilingual signs as well as braille are used to accommodate disabled citizens. These are becoming a more standard requirement. If you need to include different languages, scripts and languages for people with disabilities, make sure the typeface choice has a comprehensive character set or can be married well with other scripts. From the onset, plan the layout to accommodate the various language options separating one from another in a consistent and functional manner.

    • Numbers


      Numbers—like letters or punctuation—are considered arbitrary symbols as they hold no visual relationship to the objects or ideas they represent, whether numbering a page or playing a crucial part in signage. When possible, select a typeface with both lining and non-lining numerals.

      Lining figures are all the same height, usually slightly less or equal height as capital letters of the same typeface, sitting neatly on the baseline. Lining figures are rhythmically constant, usually monospaced and are often used when numbers line up in columns such as in lists or tables.Lining numerals are often used for alphanumerical codes.

      In contrast, non-lining figures have individual widths, descenders and ascenders and don’t line up on the baseline. They’re most appropriate for running text as they typically blend into the text better than the lining figures.

    • Numerical Properties

      Numerical Properties

      Numbers can sometimes carry superstitious values or be associated with esoteric meanings influenced by the culture they’re integrated in. For westerners, 7 is a lucky number and 13 is bad luck. In many air carriers, row 13 is usually missing. For many in Asia the number 4 signifies death, number 9 is good luck. In China for example, doors are carved with 9×9 pins to signify good luck. The use of some numbers may need to be avoided in some sensitive contexts such as hospitals.

    • Picto Direction

      Picto Direction

      When arrows support other symbols, they must be placed in the correct sequence of hierarchy, priority and reading order. Ideally, a symbol combined with an arrow should face in the same direction as the arrow itself.

    • Pointers


      Another way of showing direction is through the use of pointers such as graphic footprints (on the floor) or a pointing hand, also known as a printer’s fist. Direction can also be conveyed or emphasised by the direction of a symbol itself, i.e. a symbol walking to the right to show right direction.

    • Prohibition and Negation

      Prohibition and Negation

      Traffic signs have standardised prohibition such as red circles. A ban or negation is often visualised with supporting symbols such as a cross or a diagonal line over an image below. Usually, diagonal lines at 45 degrees are best at conveying prohibition. Horizontal or vertical lines are not usually advisable as they may denote division rather than prohibition. Prohibition and negation supporting elements are symbols in their own right and deserve similar consideration as any other symbol in the system. Be reflective of the visual dynamics between the negation line and the object.

    • Punctuation


      Punctuation marks are symbols that determine the meaning and tone of sentences. In pictographic contexts, when combining text with symbols, punctuation should be reduced to a bare minimum. Full stops are not often needed for text supporting symbols. Similarly, no full stops are needed for abbreviations, titles or personal names. Punctuation symbols can also be used to organise information. Czech Modernist Ladislav Sutnar used parentheses, symbols and small images and brackets to emphasise hierarchical structures of information.

      Of similar importance is the correct use of punctuation symbols such as apostrophes, quotation marks, foot and inch marks and ellipses. While the apostrophe indicates the possessive case, plurals of letters and the omission of letters or numerals, foot and inch marks are the symbols for the measurements of feet and inches.

      Key text:
      Design in Action by Ladislav Sutnar

    • Size and Space Economy

      Size and Space Economy

      Equal concerns revolve around space economy. Without interfering with the readability and legibility of the typeface, a narrower cut is usually preferred to a broader one. Similarly, typefaces with smaller x-heights accommodate more characters in a given measure.

    • Stroke Widths (Fats and Thins)

      Stroke Widths (Fats and Thins)

      Whilst a typeface designed for extended reading allows for smaller sizes and greater distinction between stroke widths, a typeface designed for spatial contexts and signage requires balance between stroke widths. This is whilst still maintaining good levels of contrast between letters and numbers. If possible limit the number of typefaces and weights to enforce consistency across the system, and avoid typefaces with high contrast stroke widths.

    • The Symbol as Extension of a Typeface

      The Symbol as Extension of a Typeface

      Symbols can be designed as family members of an existing typeface. Whether the foundation is a sans serif or serif typeface observe, analyse and deconstruct its various anatomical properties. The typeface’s physical properties will become the visual blocks or modules that will eventually inform the construction of the symbols. Consider thins, thicks, x-height, cuts, angles and counters. These elements will inform the pictographic system, but you may need to adapt the elements from the typeface for application in context. Experimentation is important in making sure that only the most appropriate blocks are used to bind the pictographic system with its typeface.

    • Type Size and Reading Distance

      Type Size and Reading Distance

      Type size is determined by the distance at which letters can be read and its capability to stand out in its setting. The maximum reading distance can be calculated as the multiple of x-height times 400–600 times.

    • Typeface


      Although typography for signage is different than typography for print, they both require good typographical foundations. Just like ‘good’ typography, which guides the reader comfortably through the content rather than the form, ‘good’ signage ought to be as invisible as possible, guiding the user through space effortlessly.

      Reading in a spatial context is very different to reading print. Whilst the print context assumes the reader to be in a fixed location and with a fixed reading distance, in an environment there can be the assumption the reader is moving while reading, with varying reading distances and usually with greater levels of distraction. For this reason, typographical uses for spatial contexts require different considerations than those for print.

      Things to consider include, for example, horizontal or signs in an angle only function at close reading range; wheelchair users and children have reduced fields of vision.

    • Weight


      In typography the term weight refers to the thickness of the characters outlines relative to their height. When designing for pictographic contexts chose a typeface with a relevant selection of weights. Study the content well: the symbol may be accompanied by only one weight but often other design elements of a project such as editorial need a greater selection.

  • Maps

    Maps are visual representations of information of real or imagined spaces. This section presents multiple families and types of maps.

    • Choropleth Map

      Choropleth Map

      A choropleth map is a type of statistical map that displays data organised into class intervals by means of shaded, coloured or patterned geographical areas or regions. As a general rule, the higher the value of the area, the darker the fill used.

      One of the downsides of using choropleth maps is that the selection of class intervals and associated fills tend to be arbitrary. Also, data in choropleth maps must be normalised, that is, values measured on different scales must be adjusted to a common scale for accurate reading. For example, calculating population per square kilometre rather than just showing population numbers per region.

    • Flow Map

      Flow Map

      Flow maps show movement, flow and distribution of information geographically, from one location to another. Direction is indicated by arrows and can be enhanced by other symbols. The width or thickness of the flow lines represents the amount of flow, so the thicker the line, the larger the quantity of flow.

      Usually, flow maps start at a point of origin that branches out, but can also show incoming movements.

  • Notes

    • Continuous and Discrete Data

      Continuous and Discrete Data

      Continuous data is data that can take any value within a range (2, 2.1, 2.2, 2.3, …).

      Discrete data is data that can only take values that are certain (1, 2, 3, …).

    • Cube Root

      Cube Root

      The cube root is a number x that when multiplied by itself 3 times is y: the cube root of 64 is 4 because 4 × 4 × 4 = 64.

    • Cubit Unit

      Cubit Unit

      A unit for measuring volume. If the unit is metre, volume is expressed in cubic metre:

    • Pi


      Pi or π is a ratio and a mathematical constant. For any circle, π is the division of the circumference by the diameter. Pi is often rounded to 3.14.

    • Square Number

      Square Number

      A square number is the product of the multiplication of a number with itself, for example, the square number of 4 is 16 because 4 × 4 = 16.

    • Square Root

      Square Root

      The square root is a number x that when multiplied by itself is y: the square root of 16 is 4 because 4 × 4 = 16.

    • Theta


      Theta or θ, is a a variable used to represent angles in degrees.