Draw and fill a signal

Question

I would like to draw and then fill a signal using graphics.drawcurve and graphics.fillclosedcurve as following:

Graphics

gX = drawPanel.CreateGraphics();
Pen pen1 = new Pen(Color.Black); 
Brush be = new SolidBrush(Color.Gray);
gX.DrawCurve(pen1, pointArray1, 0.01F);
gX.FillClosedCurve(be, pointArray1);

Although there is no minus in the plotted data I got some filled curved at the minus side of the curve (due to interpolation?) as following:

How can I get rid of these artifacts?

Thanks in advance!

Answer 1

Do not use DrawCurves to plot real data!

They look nice and are useful when creating a freehand plot of your mouse movements.

But when plotting data they are not so good as they tend to overdraw esp. when the direction changes quickly.

See here for an instructive example of overdrawing! Setting a Tension is a way to limit the problem; but it will also limit the smoothness of the lines..

The solution there uses Beziers, but this not what you should do!

With the great number of dara points you seem to have I suggest you stick to DrawLines & FillPolygon instead; they still should look rather smooth..