The 3D sprite technique is proposed, which enables to rapidly update 3D images of the lenticular type 3D display. The 3D sprite technique was developed for the 72-directional display which consists of a WQUXGA (3,840×2,400) LCD panel and a slanted lenticular sheet. It displays a large number of directional images in 72 different horizontal directions with nearly parallel rays. When using a slanted lenticlular sheet, the image interpolation is required in the image
interlacing process. The time required to update the whole 3D image is about 0.5 second using a PC (Pentium4 2.4GHz). The 3D sprites were implemented by software. The developed software has the ability to display 40, 12, and 4 sprites at the video rate (30 Hz) for the sprite sizes of 8×8, 16×16, and 32×32, respectively. The 3D sprite technique developed in the present study has following features: (a) supports three different data types (2D type, 3D type, and 360° type), (b) variable image size (8×8, 16×16, 32×32, and etc.), (c)scaling sprites depending on the z-coordinates, and (d) correct occlusion of sprites depending on z-coordinate. The 3D sprite technique is combined with the fingertip detection system to construct a virtual reality system in which the 3D image is interactively manipulated by the fingertip.
The high-density directional display, which was originally developed in order to realize a natural 3D display, is not only a 3D display but also a high-appearance display. The appearances of objects, such as glare and transparency, are the results of the reflection and the refraction of rays. The faithful reproduction of such appearances of objects is impossible using conventional 2D displays because rays diffuse on the display screen. The high-density directional display precisely controls the horizontal ray directions so that it can reproduce the appearances of objects. The fidelity of the reproduction of object appearances depends on the ray angle sampling pitch. The angle sampling pitch is determined by considering the human eye imaging system. In the present study the high-appearance display which has the resolution of 640×400 and emits rays in 72 different horizontal directions with the angle pitch of 0.38° was constructed. Two 72-directional displays were combined, each of which consisted of a high-resolution LCD panel (3,840×2,400) and a slanted lenticular sheet. Two images produced by two displays were superimposed by a half mirror. A slit array was placed at the focal plane of the lenticular sheet for each display to reduce the horizontal image crosstalk in the combined image. The impression analysis shows that the high-appearance display provides higher appearances and presence than the conventional 2D displays do.