I believe you could use this term for your translation, even though this Wikipedia article talks more about the technique which may not apply to your context per se.

http://en.wikipedia.org/wiki/Contour_drawing

Contour drawing, is an artistic technique used in the field of art in which the artist sketches the contour of a subject by drawing lines that result in a drawing that is essentially an outline; the French word contour meaning, “outline.” [1] The purpose of contour drawing is to emphasize the mass and volume of the subject rather than the detail; the focus is on the outlined shape of the subject and not the minor details. However, because contour can convey a three-dimensional perspective, length and width as well as thickness and depth are important; not all contours exist along the outlines of a subject.[2] This technique is manifested in different styles and practiced in the honor of drawing development.