I've been drawing portraits for some time, both realistic and stylized. I can draw from imagination for profile, 3/4 and face-forward views. But I want to be able to draw from imagination all views: from below, from above, etc.
Currently I have a little plastic head maquette that I use for reference when I do this. How do I learn to do this from imagination?
Do sketching first and then practice.
Look at sketches of the rotation of the head like Drawing Faces from All Angles , study anatomy and drawing solids, then you can sketch your character, then do character design.
After the design is complete, try to sketch and draw your imaginary character.
It will be nice for animation, game concept art, realistic fantasy art, and more. (See Tron: Uprising examples on Pinterest).
If your drawing skill is realistic, try using Google Search for character concept art.
I've got some manga art books that are helpful - they give guidelines for drawing heads/bodies at all sorts of angles, whether by using skeleton frameworks, or just drawing freehand.
Also, if you're happy taking a sketchbook around with you, try doing 20-second speed sketches of real people (using pencil, biro, or whatever medium you prefer). Real people don't tend to stand still that long, so you'll have to be quick, but it's a great way of practising natural head positions. (Places like shopping centres or looking out of café windows can be helpful - some places put you below head level, and other put you a storey or two above where people walk).
