Extremely Efficient Visualization Makes Use of Color and Symbols

Not too long ago, I posted a 'heat map' visualization and I said it was an efficient visualization because the plot space was filled with color. But it represented only one quantity.

Well now I took that idea further and made a visualization that represents three (or four depending on how you count) quantities. The following picture represents flow around a cylinder with the following quantities:
- flow potential     background color
- flow direction     direction of arrows
- flow magnitude   length of arrows
- pressure              color of arrow
I even threw in a max and min pressure point in there too.

No need for multiple plots or a third dimension!