The 3 curves dominantly viewed as no-type, such as the black curve connecting roman’s shoulder and chest armour in Figure 11, are adjacent to strokes of known curve-type. Our algorithm by default reconstructs these strokes as shell projections once their end-points have been defined in 3D by adjacent curves. Exhaustive classification of all curves on roman by one viewer in Figure 1(b) reported only 9% strokes as having no-type, and these were conveniently reconstructed in 3D in context of their adjacent strokes. In summary, we believe this study provides sufficient validation that viewers consistently perceive sketch strokes in layered 3D models, and our algorithm is able to reliably match viewer expectation.