Outlines are modeling object that are drawn on Surface Planes. Outlines are objects drawn on photos to trace a flat shape or pattern. Outlines are like Surface Draw objects (see Surface Drawing) in that they are defined by points drawn on a single photo and use an associated 3D surface to obtain their position in 3D, and do not need to be referenced. Compared to Surface Draw, Outlines are more CAD-like – the shapes that are drawn are smoother and easier to draw (e.g., with repeatable Fillet radius settings).