Figure and ground refer to the identifiable shape (figure) and surrounding area (ground) in a visual field. Traditionally, the figure is considered the positive space or object that stands out, while the ground is the negative space or background surrounding the object. However, figure and ground can be interchangeable depending on one's focus. Plumb lines, which are undeviating vertical lines, are often used in drawing to help find the relationships between figures by establishing alignments and using negative space between objects. Creating a viewfinder can also help with composition by establishing object relationships and edges of the picture plane.