Volumetric displays create visual representations of objects in three dimensions, with an almost 360-degree spherical viewing angle in which the image changes as the viewer moves around. True volumetric displays fall into two categories: swept volume displays and static volume displays. Swept volume displays use the persistence of human vision to re-create volumetric images from rapidly projected 2D “slices.” Static volume displays use no major moving parts to display images, but rather rely on a 3D volume of active elements (Volumetric Picture Elements, or voxels) changing color (or transparency) to display a solid option.