From CS294-10 Visualization Fa08
A good visualization
Source: East Bay Express, August 27-September 2,2008 Volume30, Issue47
This is an advertisement of clothes. It only shows three things; two children in jeans, a digit representing price and a business logo. It seems to be very simple but easily to be understood what the advertisement want to say. That is to say, the company want to sell jeans for children at designated price. Information is expressed almost implicitly but understood explicitly. So,this is a good example of concise visualization.
The data for the visualization is so simple. Two children in jeans and the number representing price are substantially independent of each other. However, we can intuitively realize a relationship between them.
A bad visualization
Source: IEEE Spectrum June 2007, p31
This is a graph showing resource flows and ecological footprint in London. So,the diagram shows how resources are used and wasted in London. This visualization allow us to quantify the energy and materials consumed by London, and to compare the resource flows with the other country's resource flows. Intuitively, precede objectives are achieved but some essential explanations are missing on this visualization. As a result, It is hard to understand detailed statistics.
Intuitively, the following thing on the figure are easily understood. To represent resource flows, several materials "Construction and demolition materials", "Food", "Wood" and "Everything else" are chosen. Furthermore, To represent energy flow, some main energy resources "Gas", "Liquid fuel" and "Electricity" are chosen to show CO2 emission. Each small cube represents 100 thousand metric tons of any materials. Every category has a relationship by an arrow which represents output flow from a category and input flow to other category. However, the following defects make user hard to retrieve data from the figure. Problem1 : Each category shows its total amount of material and its proportion of each material. But, Some categories do not show their total amount and Problem2 : An arrow shows output from the category. But at inter flow point, the total amount of outflow is not equal to pointed category's amount. Problem3 : Energy flow appears to be input flow to "Consumption" and be added to it. However, It is not true. Energy is just resource and facilitates consumption,so not added to materials. Problem4 : Small cubes represent amount of materials, but there are too many cubes to count them. So, to estimate total amount of cubes is very tedious. So, we are almost confused of understanding the figure, for less explanation.
To solve problems mentioned above, I made a completely new figure. First, I change each set of cubes representing amount of materials into pie graphs. This way can allow users to more rapidly compare proportion of materials in the category. In addition, I put total amount of materials on every category. Then, If need, we can calculate detail amount of certain material in the category. Second, original graphic has little color correlation between materials. So I set unique color on each material and hold the color rule consistently. Moreover, I put a graph legend in the upper right. Third, to clarify the resource flows among categories, I changed original arrows representing resource flow direction into unbent them ,since some of them have turnaround and it may get users confused. This helped with user to realize resource flows comprehensively.