Today in my Drawing class, we are working on light and shadow using the shapes as reference. As always, proper proportions are necessary as is the perspective from which you are viewing the objects you are drawing. So we begin by moving our desks closer to the lit objects in the centre of the room and prepping our drawing area for the task at hand.
Above is an example of the way light falls on objects and how we respond as artist with tone and shadow. The numbers represent the value range. We must keep in mind our value scale/ tone if the drawings are to describe the shape in space realistically.
For our purposes the optimal source of light is a single source of light where everything is illuminated by the same incident light. In our case we brought in a light source and turned out the rest of the lights in order to emulate the sun. This helps to eliminate the confusion that multiple light sources creates.
Here is a drawn sphere with the terminology outlined in this class. It is important to keep in mind the difference between smooth and curvilinear and shapes as opposed to hard angles and surfaces which are much easier to shade.
For reflected light to bounce back up onto a surface must be at an acute angle to that surface. IN this case the cone like pyramid shape (to the left) does not have reflected light hitting the flat area where the core shadow resides. The icosahedron object (to the right) has reflected light bouncing back up on its surface creating a lighter tone even though it is further away from the source of light and below the core shadow. If the shape like a cone or pyramid is sloping back away from the surface it is sitting on, there is no way fro the light to bounce up on it in order to create a reflected light in the shadow.
The surface must be more than perpendicular or overhanging the surface in which the reflected light is bouncing onto the object from.
When one objects cast shadow drapes across the core shadow of another object there should not be any criss cross lines and confusion. The pyramid to the far right cases a shadow over the cone object and where fit meets the core shadow they seamlessly blend together.
One good trick for seeing the values of the tons that I like to pass onto students is squinting. If you squint you will have a much easier time judging the many values int eh scene in which you are drawing. This also helps turn colours into values and to simplify the shapes that make up what you see.