The trees' 2x2-cell drawings unfolded onto the ground as quarter-hull
pancakes -- each tree read as cut in half. The carver is now parametric
over its canvas: a `canopy` anchor tile carves the whole 2x2-cell
drawing as ONE 32px hull, and stamps carry their footprint radius. The
stumps' drawn tops are a cut face, not body: the `stump` class builds
the hull from the bark rows and projects the ring ellipse across the
round flat top, near arc south (stump_cap = the ellipse's drawn rows).