How to set representation from points to surface?

Hello everyone, I am a newbie in vtk, I want to create the application with winform to visualize a science data. Specifically, My data is a “.vtk” file format, with uniform structured and scalars data.
I already try this code:

        // source: reader
        vtkDataSetReader reader = new vtkDataSetReader();
        reader.SetFileName(filePath);
        reader.Update(); // here we read the file actually

        // Filter
        vtkImageDataGeometryFilter geometryFilter = new vtkImageDataGeometryFilter();
        geometryFilter.SetInputConnection(reader.GetOutputPort());
        geometryFilter.Update();

        // Mapper
        vtkPolyDataMapper mapper = vtkPolyDataMapper.New();
        mapper.SetInputConnection(geometryFilter.GetOutputPort());

        vtkProperty property = new vtkProperty();
        property.SetRepresentationToSurface();
        property.LightingOff();
        property.EdgeVisibilityOn();

        // Actor
        vtkActor actor = new vtkActor();
        actor.SetMapper(mapper);



        // get a reference to the renderwindow of our renderWindowControl1
        vtkRenderWindow renderWindow = renderWindowControl1.RenderWindow;
        // renderer
        vtkRenderer renderer = renderWindow.GetRenderers().GetFirstRenderer();
        // set background color
        renderer.SetBackground(255, 255, 255);
        
        // legend
        vtkScalarBarActor legend = new vtkScalarBarActor();
        legend.SetLookupTable(mapper.GetLookupTable());
        legend.SetTitle("Title");
        legend.SetNumberOfLabels(3);
        legend.SetMaximumWidthInPixels(50);
        legend.SetMaximumHeightInPixels(400);
        legend.SetPosition(0.9,0.1);
        
        //double [] x = legend.GetPosition();

        // add our actor to the renderer
        renderer.AddActor(actor);
        renderer.AddActor2D(legend);

And this is my results:

In code, I already set the representation to surface, However I can not get an expected results ( same paraview results), Could you please suggest me a method to do this?

Thank you so much!!!