Surface charts are a good way of displaying 3-dimensional data in Excel. Use them when you have two independent variables and a third variable that’s dependent on both of them.
Our worksheet contains air velocity data for a square duct. There are two independent variables: horizontal position and vertical position. The air velocity is the dependent variable.
We’ll use a surface chart to show graphically how the velocity varies at the different positions within the duct. There are two different kinds of surface charts in Excel – contour charts and 3-D surface charts.
To create a contour chart, select all of the data including the position values. Go to the Insert tab and choose the Insert Surface or Radar Chart button: Choose the third button to create a Filled Contour chart:
The default coloring on the surface doesn’t have a lot of significance. It’s based on the color scheme that has been chosen for the worksheet.
It will be easier to tell whether the values are large or small with a monochromatic color scheme. Go to Design > Change Colors, and choose a monochromatic scheme. The first group of monochromatic schemes will assign a dark color to small values and a light color to large values. The second group, beginning with Monochromatic Palette 8, will do the reverse. Choose one of those color schemes (see below, left) so that the large values are shaded dark which yields the chart on the right:
As always, we can add axis titles. Select the chart, click the green plus sign at top right, and check the box next to axis titles. The z-axis title will appear at the chart’s lower left. Select it, then triple-click on it to change the title to “Air Velocity(m/s).” If you can recall, we can also set the axis titles to values in existing cells. Triple-click the axis label, go to the formula bar, enter an equals sign and select the cell containing the appropriate title. Add a chart title to finish labeling this chart.
If we want to visualize the data as a 3-D surface chart, we can easily change the chart type by selecting Change Chart Type from the Design tab and choosing the 3-D Surface Chart option. Click OK to apply the change to the chart.
To adjust the orientation of the chart, right-click in the chart area and select 3-D rotation. In the Format Chart Area task pane, we can change the x-axis rotation, y-axis rotation, or the perspective. For this chart, we’ll use an x-rotation of 20°, a y-rotation of 20°, and a perspective of 15°.
You can make the monochromatic gradient finer by decreasing the major units on the z-axis. Right-click on the axis (the numbers ranging from 0-5), select Format Axis, and change the major units to a smaller value (0.1).
This gives the surface a very fine gradient for a smooth, blended appearance, but it also results in too many labels on the z-axis and in the legend:
For this chart, a major unit of 1 is preferable.