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The handling of perspective marks the difference between the amateur and the professional. Every object drawn has to have an eye level or horizon, felt if not actually represented. On the left we see the planes of the head as seen from above or below the eye level. If a head were as big as a building it would be affected by perspective in the same way as a building is.
Learn about drawing in perspective:
The Complete Bridgman Part 2
Linear and Aerial Perspective
Selection of reference plates
A selection of reference plates that can give you some suggestions about how to draw the head in perspective. These reference charts are provided by the Internet using search criteria “head perspective” in Google (images).
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