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Fitting an Accurate set of Spot-heights

Contour plots are often an excellent alternative to 3D presentations where the object is to model three-dimensional data. Obviously, they can be used ‘just like a map’ where you may have a set of spot-heights (z-values) at various locations on the xy-plane. If the z-values really represent accurately measured values (spot heights in a landscape) then the map should be forced to fit itself around them.

This example increases the mesh-density (to compute the contours at many more points) and sets the flexibility high enough to force the contours to behave correctly with respect to the points nearby. Whether this map is better than any other is (of course) arguable. It is an interesting exercise to take a set of points like this and attempt to make the map by hand.

SharpPlot sp = new SharpPlot;

zdata = new int[] {100,15,27,117,19,112};
xdata = new int[] {17,31,29,21,30,24};
ydata = new int[] {190,270,310,300,190,230};

sp.Heading = "Trend Surface (Close Fit)";
sp.SetAltitudeColors(new Color[]{Color.Navy,Color.Green,Color.GreenYellow,
         Color.Khaki,Color.Silver,Color.White});
sp.ContourPlotStyle = ContourPlotStyles.ValueTags|ContourPlotStyles.ExplodeAxes|
         ContourPlotStyles.AltitudeShading;
sp.SetMarkers(Marker.Bullet);

sp.Flexibility = 8;
sp.MeshDensity = 5;

sp.DrawContourPlot(xdata,ydata,zdata);

Worked Examples

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