This above is sketched out of my head. More detail is needed - so I find some real trees.

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I start refining the images from a real tree and progress through a series of sketches.

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I arrive at a form I like in the sketch above, and then copy it to a piece of paper the exact dimensions of the surface. (Below)

The trailing toe needs to be modified, but I am ready to paint the background in and have set it in on to the surface by smearing charcoal though tiny holes in the paper.

A rough color test.