WPF continuous drawing

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C#

WPF

I have created a chart using the code from this link http://csharphelper.com/blog/2015/04/draw-a-3d-surface-from-a-set-of-data-points-with-an-altitude-map-using-wpf-and-c/[^]

In my code the application redraw the graph in a particular interval. But this will draw the graph only once. Please help me to solve this error. My chart drawing function is

MainModel3Dgroup.Children.Clear();
           double[,] val = CreatePoints(newval);

           xmin = 0;
           xmax = val.GetUpperBound(0);
           dx = 1;
           zmin = 0;
           zmax = val.GetUpperBound(1);
           dz = 1;

           texture_xscale = (xmax - xmin);
           texture_zscale = (zmax - zmin);

           // Create an altitude map.
           CreateAltitudeMap(val);

           // Create the model.
           DefineModel(MainModel3Dgroup, val);

           // Add the group of models to a ModelVisual3D.
           ModelVisual3D model_visual = new ModelVisual3D();
           model_visual.Content = MainModel3Dgroup;

           MainViewport.Children.Clear();
           // Display the main visual to the viewportt.
           MainViewport.Children.Add(model_visual);

I have uploaded the sample code in this link. In this application a new image will drawn from a button click but its not working correctly http://www.filedropper.com/howtosamplealtitudemap[^]