Most people have the pre-conceived notice that the head is more or less shaped like an egg. In fact, the head is much squarer than we think. The egg awareness is one of those simplified pre-conceived symbols the brain uses as a means for quick recognition.
Most beginning students will usually render the face on paper as a flat disk or oval which it is not. Also, compared to the entire head, the face is quite small particularly in babies. Your hand can fit the entire face. Place that same hand on top of your head and you will know immediately how large your head really.
To understand planes and thus obtain a sculptural sensitivity in your drawing you must understand and use simple geometric shapes.
In general, the skull can be framed within a rectangular box. More accurately, this rectangular box should be adapted to a phalanx-like box with the face on the smallest side. The skull tapers towards the front which is the face. This is the basic shape of the head in the frontal view.
In the profile view the skull is generally a cube. The difference is the facial angle (the "muzzle") that slopes slightly forward at the chin. In the 7/8 profile, the cube has simply been rotated in space.
Again, it is very important to think about the head in terms of simple geometric shapes. Once you have positioned the large simple shapes you can start positioning the smaller shapes inside the large ones. Pretty soon that collection of simple shapes becomes quite complex and starts resembling a head.
Keeping the above in mind you can start with striking the arabesque which is the entire outside contour of the head, hair included. Then you break down the arabesque into its various sections such as the hair, ear, jaw and neck.
As you block in the darks and think of the head as a collection of simple geometric solids you will already begin to see the 3-dimensional effect, even at this early stage.
The key is to think simply and large. At this early stage, do not pay attention to the details – they tend to mislead your sense of length and direction.
Once the major elements are established placing the features (eyes, nose, etc.) becomes relatively easy. However, if you do not establish those elements correctly you will never be successful.
The frontal view of the portrait poses a unique challenge. If you are not careful you can end up with a flat, 2-dimensional face. In this view, the plane changes are often quite small and difficult to place.
Be sure to notice all plane changes in this frontal view and render them carefully in your drawing:
– Showing the forward tapering of the sides of the face is critical to achieving a minority 3-dimensional effect in this frontal view.
– The front of the face lies more or less in one plane.
– The plane of the forehead changes direction as you move towards the top of the head.
– The plane along the cheek has a different direction than the neighboring one along the temple.
The idea is to carefully observe the directions of all the different planes that make up the skull and take these differences into account when you draw. If you do, your drawings will possess a sculptural, 3-dimensional sensitivity. It is not necessary to draw out the geometry of the actual planes, but the differences in direction must be clearly rendered.
In conclusion, it is very important that you are aware of the fact that a subject's head consist of planes with different directions and is not just an egg. This sculptural structure should be reflected in your drawing because it is essential to the likeness and to the illusion of 3-dimensionality.