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Terminators and Cast Shadows

Do you know the difference between the terminator and the edge of a cast shadow?

Terminators are outlined in red Cast Shadow edges (and other contours) are outlined in Green (Cast is the right eye of Michelangelo's David)

If you heard "terminator" and couldn't help but say "I'll be back", you are not alone! Having introduced hundreds of students a year to the concept of the terminator while living here in California where Arnold was our "Governator" for eight years, you cannot make a Terminator joke I have not heard!

Arnold Schwarzenegger as the Terminator

A termination is a clear and precise ending, whether the last station on a train track or the last moment of a life. When drawing, a "terminator" is simply "the ending of the light".

Just as the surface of the earth curves away from us and ends in a horizon line, the lighted surface of a rounded 3-dimensional form curves away from the primary light source and abruptly ends in shadow. Since light cannot bend it cannot wrap around turning form, so the terminator is the line beyond which the primary light source cannot reach: The termination of the light. Thus the Terminator.

Meanwhile, cast shadows are created when one form blocks the light from hitting another part of the form, just like your shadow on the pavement on a bright sunny day. "Cast" means "throw", so a cast shadow is the shadow "thrown" from one form onto another surface.

To find an elusive terminator, hold a skewer so it casts a shadow on the surface of the cast. Since you cannot cast a shadow into a shadow, the cast shadow of the skewer will abruptly end when it meets the terminator, which in this case is in the middle of the upper lip.

Understanding which shadow edges are terminators and which are cast shadows is part of understanding the 3-dimensional form of your subject and how it is being lit by the primary light source.

Students in my Bargue Plate Drawing and Cast Drawing online courses are taught how to outline their shadow shapes and diagram the terminators and cast shadows with two different colors before they start shading, so they have a complete understanding of their subject and light source.

Creating a convincing and compelling drawing that captures the shape of the form and the feeling of the light requires understanding our subject and how the light is hitting it. The more we understand about our subject, the more our drawings and paintings are infused with clarity of thought.

This is Sarah Connor from the Terminator movies. She has nothing to do with drawing, aside from her determination and relentless single-minded focus.

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