A Contour Line is a line that defines the inner and outer edges of a form and suggests three-dimensionality.
In this sketch done in my drawing 1, class cross countour lines are also used.
Cross-Contour lines are multiple, curving, parallel lines running over a surface of an object horizontally and/ or vertically which describes its surface topographically.
The image shown is of a still life of sheets placed overlarge boxes in the drawing room.
