Top: Thi Bui set up her drapery study to fill the entire space of the page; she added the section in the lower front to make the composition even more compelling. Bottom: Looking at the photograph "Wall Curves" from the Visual Symphony book, you see that the drapery is no different than a landscape; it is just a matter of scale.
The drapery setup as seen in class (above left) and after tonal adjustment in Adobe Photoshop (above right). Notice that in the photograph, to achieve a full range of tones within the folds of the drapery, we ignore the value of the wall it lies against. This has the effect of making the drapery look like a knockout or a cutout. In your drawing, you must relate the figure to the ground in order to maintain the illusion that the drapery resides in a three-dimensional space.