Crosscontours

Cross-contours are internal lines drawn on the surface of a three-dimensional object that run across the form, typically perpendicular or obliquely to the outer contour. They describe changes in surface orientation and curvature, helping to convey volume beyond what the silhouette provides.

Compared with contour lines, which trace the boundary of the object, cross-contours follow the shape of the surface itself and change direction as the surface bends. They are useful for indicating the way a form turns in space, for suggesting depth, and for coordinating shading with the underlying geometry.

Practical drawing approach: begin with a light sketch, then add a series of curved lines that wrap around the form. Lines should follow the surface flow, bending with features such as the head or limb. Use spacing to imply foreshortening and light; avoid crowding lines and rely on a thoughtful balance between contour and cross-contour data.

Applications: cross-contours are taught in figure drawing, sculpture, product design, and digital illustration as a way to train perception of form. They complement shading and hatching by clarifying surface orientation, but do not replace the role of lighting in defining volume.