Visualizing Data

Displaying patterns in complex datasets, communicating aspects we think are important.

Cartography

The art and science of making maps.

• Why do we make maps?

• To transmit spatial information to a map reader

• Data and analyses are meaningless, unless conveyed effectively

• Decide what you want to communicate and to whom

Cartography

Good Maps

1. Concise
2. Accessible
3. Aesthetically pleasing

Bad Maps

1. Cluttered, ineffective, misleading
2. Inaccessible to target audience
3. Ugly

A Bad Map

Excellent example of a bad map showing really interesting information.

• Too much information
• Too many colors
• Text is way too small

A Better Map

Cleaner, less complex presentation.

• Too much information
• Too many colors
• Text is way too small

TopHat Question 1

Cartography is the ___ and ___ of making maps.

Design Principals

Give the viewer the most information in the shortest time with the least ink in the smallest space.

• Complex ideas communicated with clarity, precision, and efficiency.
• Maximize data-to-ink ratio (i.e. more data, less other stuff).
• Erase non-data ink, within reason.

Design Principals

The best maps can be interpreted quickly and easily.

• Title: Clear and to the point
• Content: Patterns are obvious, no “extra” information

Design Principals

The best maps can be interpreted quickly and easily.

• Content: Takes longer to read, but subject matter is more complex
• Minimizes “extra” information
• Simplifies geometry

Data Symbolization

The techniques we use and choices we make to represent information on a map.

• Color & brightness
• Shapes & lines
• Characters & fonts
• Position & size

Data Symbolization

The techniques we use and choices we make to represent information on a map.

• May lead to assumptions being made about the data
  • Intentionally or otherwise

Color

The HSV scale describes three components of a color

• Hue: the dominant wavelength
  • Typical association with the term “color”

• Saturation: the level of dominance
  • All red or only a little?
• Value: the brightness / intensity

Color Choice

Qualitative

• Different hues,
• Fixed value and saturation
• Best for nominal scales

Sequential

• Fixed hue
• Increasing value and saturation
• Best for ordinal & ratio scales

Diverging

• Opposing hues
• Diverging saturation
• Best for interval scales

TopHat Question 2

This type of color map would be best suited for which variable?

• Land use (Forest, Agriculture, Urban, etc.)
• Temperatures (in Kelvin)
• Temperatures (in Celsius)
• Zoning Density (High, Medium, Low, etc.)

Color Choice

Some colors have implicit assumptions depending on the context.

Color Accessibility

About 4.25% of people are colorblind, red-green is the most common. Color Brewer is a great resource.

Type of Phenomena?

Discrete:

• Points/lines/shapes
• Hues

Continuous:

• Surfaces, contour lines
• Saturation and value

What is the Measurement Scale?

Nominal:

• Dashes, shapes
• Different Hues (colors)
• Do Not choose colors or sizes that imply a difference in magnitude

What is the Measurement Scale?

Ordinal, Interval, or Ratio:

• Graduated symbols, line weights
• Different shades/intensities
• Do Not choose colors or shapes that imply a difference in category

Visual Hierarchy

Relative importance is implied by layout, our perception is influenced by the order in which we see things and how big / bold they are.

Placement

• Center first
• Top to bottom
• Left to right

Font

• Larger
• Bold
• italics
• Smaller

Contrast

• Dark on Light
• Light on Dark
• Light on Light
• Dark on Dark

TopHat Question 3

Visual hierarchy describes how some hues (colors) are more important than others and how the choice of hue influences our perception of a map.

• True
• False

Stylistic Guidelines

1. Clear labeling to prevent ambiguity and confusion.

• Proof your map text

2. Consider if all map elements are necessary.

• Scale bars, North arrows, etc. minimize “junk”

3. Use appropriate color scheme, suited for data type

• Colorblind friendly & high contrast

Stylistic Guidelines

• North arrow not needed:
  • At poles
  • Familiar region
• Scale bar not needed:
  • Familiar region
  • Text can often suffice
  • Can vary across the map

Stylistic Guidelines

• North arrow needed:
  • Unfamiliar region
  • North not up
• Scale needed:
  • Unfamiliar region
  • If navigation is goal
  • Maps at different scales

So Many Mistakes!!

• Poor use of map space
  • Wasted white space
  • Not centered
• Poor color choice
  • Not colorblind friendly

So Many Mistakes!!

• Not all map elements are visible
• Text/font issues
• North arrow
  • Placement
  • Size & style
• Scale bar
  • Wrong units!

So Many Mistakes!!

• Legend issues
  • Avoid unnecessary text
    • Don’t title it Legend
  • Make sure entries are meaningful
  • Get rid of underscores

So Many Mistakes!!

• No name / affiliation, date, or data source
  • Be transparent, readers deserve to know:
    • Who made the map?
    • When was the map made?
    • Where did relevant data come from?

Cleaner Presentation

• Area of interest takes up most of the map space
• Name, affiliation, source
• More meaningful legend entries
• Proper sizing/placement of map elements
• More pleasing, accessible color choices

TopHat Question 4

Your maps always need to have a title, scale bar, and north arrow.

• True
• False

TopHat Question 5

If you are mapping a region that your target audience may be familiar with, its you should include a north arrow and scale information (scale bar, representative fraction, etc.).

• True
• False

Cartographic Principals

These are just stylistic guidelines!

• Cartography is an art, there are no steadfast rules

• Just best practices

• Feel free to play around with styling

• Just be able to justify your choices

• Not all spaces “want” to be mapped

• Sometimes you need to make aesthetic compromises to make an effective map