Maps and the Geospatial Revolution

Lesson 5 – Lecture 2

Anthony C. Robinson, Ph.D Lead Faculty for Online Geospatial Education John A. Dutton e-Education Institute Assistant Director, GeoVISTA Center Department of Geography The Pennsylvania State University

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Choosing Colors

• Colors on thematic maps should correspond to the type of data you’re trying to show

– Do you have numerical or categorical data?

• Color schemes include three major types

– Sequential (less -> more) – Diverging (above and below an average) – Qualitative (pizza, currywurst, and tonkatsu)

Sequential Colors

Sequential Colors

Diverging Colors

Qualitative Colors

Rainbows Kill People

• Rainbow (spectral) color schemes are commonly misused on maps

– Weather maps showing precipitation amounts – Every “heat map” floating around

• They’re bad because they often use qualitative colors to show

sequential or diverging data

– Is blue more than yellow? Is purple more than blue?

• They also can kill people

– Doctors interpreting medical images of the heart made worse decisions about their patients using rainbow schemes than simple sequential schemes

Rainbows Kill People

Rainbows Kill People

Data Classification

• Assigning observations to categories is called data classification

• Three major types to know

– Equal Interval – Quantile – Natural Breaks

Equal Interval Classification

Quantile Classification

Natural Break Classification

Text On Maps

• Designing text on maps is a major aspect of cartography

• Choosing fonts and positioning labels can be a daunting task

– Labeling every

street, building, etc… and making them all readable together

Maps and the Geospatial Revolution www.coursera.org/course/maps Twitter @MapRevolution Online Geospatial Education @ Penn State www.pennstategis.com

This content is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License