Isosurfaces
An isosurface layer extracts a level surface from a scalar source — a volume, or a scalar field on a mesh — at an iso value you set with a slider ranged to that source's own data. Marching cubes runs on a volume, marching tets on a mesh, so the mesh case gets an exact surface rather than a resampled approximation. Controls: source, iso level, colour, opacity, smoothing, and flat vs. smooth face shading. A label volume gives one isosurface per visible region, in that region's own colour — brain structures, or the organs of an abdominal CT.
