Evaluation of visible region in volumetric 3D display using a rotating helical screen

We have proposed a volumetric 3D display in which cross-sectional images are projected on a rotating helical screen. One of challenges of this method is an existence of invisible regions generated depending on observation angle. Invisible region is determined as the sum of dark region as a result of oblique incidence of the projected light on the screen and blind region as a result of blocking light paths to the viewpoint by the screen body. The larger invisible region was shown against the higher viewpoint to the helical screen. It was also shown that invisible region mainly located in the distant side from the viewpoint and in the neighboring region to the rotation axis of the screen. Our evaluation results show that the cylindrical display volume provided by a helical screen offers enough visible region at the viewpoint side and the periphery: indispensable regions for 3D displays.