Capture 3DModel in high quality
===

I'm trying to capture my WPF Viewport3D, the problem is that no matter what I do it doesn't captured in high quality, what should be the parameters for the RenderTargetBitmap for best qualiity ?

     RenderTargetBitmap bmp = new RenderTargetBitmap(
                              (int)viewport3D.ActualWidth, (int)viewport3D.ActualHeight, 96, 96, PixelFormats.Pbgra32);
        
    bmp.Render(viewport3D);
    PngBitmapEncoder png = new PngBitmapEncoder();
    png.Frames.Add(BitmapFrame.Create(bmp));
        
    using (Stream stm = File.Create(m_captureWithoutMainModelFileName))
    {
       png.Save(stm);
    }


I've tried to save the image as BMP but it didn't help.