The 3/4 face reference is a helpful way to draw faces from different angles. The perspective in the 3/4 view helps you to get a clear idea of how to draw the features of a face. The eye, nose, mouth, and mouth line are all viewed from a lower perspective than they are from the front view. To draw realistic faces from this perspective, you must draw each element lightly and erase any unnecessary lines. The image below shows a good reference for drawing a 3/4 face.
A 3/4 face reference also refers to a portrait shot in which the subject is facing the camera at a 45o angle. The portrait could feature the model’s face or the neck, with a bit of the body in the frame, pointing in the same direction as the face. This type of portrait also works for portraits with people who are short. The height and stance of the model’s neck also matters. This view makes it easier to capture the model’s expressions.