Hello aspirant

hope you are doing well and safe. With reference to your query,  I would glad inform you that   Picture Plane is the flat two-dimensional surface on which we draw or project an image in perspective. It is a simple task to draw the two rectangles if they are parallel to the picture plane. Ground Plane is at 90 degrees to the picture plane.The ground plane is the grey surface on which the shapes appear to be standing.

Hope you found this answer informative. Best wishes for your future