 In a contour chart, the input data are the values of some points on the xy plane. ChartDirector uses advanced surface fitting techniques to compute the surface, and visualizes the results as colors and contours on the xy plane.
 Note the detail, smooth and fully antialiased contours in this chart. ChartDirector supports spline surface fitting. This produces smooth contours, even if the input contains only a few data points.
 This contour chart/heat map uses continuous coloring instead of changing the colors in discrete steps.
