Illusion is a playground for artists. Every artist who depicts a “solid real” object on a 2-dimensional canvas strives to create the illusion that the object viewed is 3-dimensional, and can employ a host of artistic tricks to accomplish that goal. Masters of “tromp l’oeil” (fool the eye) have for centuries created illusions of cornices, windows, balconies, and doors to enhance or enliven otherwise bare walls.
In 3-dimensional space, artistic tricks are not needed to produce illusions. Instead, our eyes and brains often supply us with illusions—we see (or think we see) something that is not really what it is. If you look straight into a shallow round bowl, your brain might not be able to decide if the shape is concave (scooped out) or convex, like a mushroom’s dome.
The viewpoint from which we observe a 3-dimensional object can be crucial to our “seeing” and understanding the object. Unless the object is transparent, we cannot see parts that are obscured by other parts that cover them. We can only see a projection, or shadow, of what is directly in front of us. Bakker capitalizes on this property to have his sculptures provide teasing puzzles—if I observe the sculpture from this viewpoint, can I guess the full sculpture’s shape? Only by rotating the sculpture in space, exploring views from many angles, can you discover its surprising symmetries.