Studies On Volumetric Display System And Its Characteristics Based On The Rotation Of A Two-Dimensional LED Panel

Volumetric display technique depicts three-dimensional (3D) images within an actual 3D space rather than upon a two-dimensional (2D) surface. The volumetric images created consequently have most characteristics similar to real-world 3D objects, providing all perspectives at once and allowing a group of viewers to directly perceive from different orientations simultaneously without the need of wearing any visual aids. Viewers can walk at will yet still receive visual depth cues to maintain the 3D appearance of images. Volumetric display technology can result in fast and accurate perception of the 3D form, spatial distribution and dynamic properties of image data, hence it has the potential to be widely used in such applications as meteorology analysis, medical imaging and air traffic control, etc.In this paper, a volumetric display technique based on the rotation of a 2D LED panel is systematically studied, concerning the theoretical design, modeling simulation, system realization, system optimization, experimental discussion and characteristics analysis, etc. Considerable staggered progress has been made. Part of this research is applicable to the volumetric display technique based on the rotation of other 2D active panels.A simulated model and a software platform of LED volumetric display system are set up in the computer. The influence of the addressing mode of LED, the attributes of voxels and the characteristics of LED panel on the reconstructed 3D image quality and the overall system performance are analyzed. These analyses provide an important theoretical basis for the successful establishment of a volumetric display system and its performance evaluation in succession. The research shows that in the case of using small LED devices of high-speed electrooptic response characteristic, adopting techniques of quick scanning and matrix addressing of a rotating thin panel which comprises a compact LED array, the position error of voxel due to the sequential addressing of LEDs and the rotation of the panel can be reduced significantly, consequently a volumetric image which has good voxel attributes and is capable of faithfully depicting the 3D characteristics of the original image will be generated.LED volumetric display experimental systems are set up based on the above-mentioned simulation. The whole process of generating volumetric 3D data, emulating a perspective display, transfering image data, addressing the LEDs and reconstructing a volumetric image are presented. One of the two experimental systems is capable of displaying images that consist of about 8.39 million voxels and can be viewed from nearly any arbitrary angle. The other is able to modulate the brightness of LED into 256 levels to display volumetric 3D gray images. The implementions of these systems have not only proved the feasibility of achieving volumetric 3D display based on the rotation of a 2D LED panel, but also establish the possibility of displaying volumetric color images in the futurer. In addition, they provide effective experimental platforms upon which the characteristics of LED volumetric display may be studied. The main advantages of these two systems are as follows. The system structure is simple and compact, the requirements of data processing are moderate, and the volumetric image display resolution is scalable, etc.The relationship of volumetric display characteristics to the system structure and the optoelectrical characteristics of the light emitting device is first studied systematically from the aspect of 3D space. The brightness difference among voxels result from the undesirable distribution curve flux of the LED panel is analyzed. The image shrink due to the variations in the LED panel's rotational speed, and the image distortion that the nearer objects seems smaller caused by an off-axis rotating LED panel are observed. In order to single out suitable values of system parameters, factors that impact on the reconstruction percent of image points and the increment percent of voxels, along with statistical rules of the position mapping error between image points and voxels are discussed. To solve the problems involved in the inhomogeneous voxel placement and density, we put forward a method based on a homogeneous quadrate 3D array. Through keeping or abandoning potential voxel positions according to the predefined space of array pixels and the position error tolerance, voxel placement can be made almost uniform. These contents have laid a considerable basis for the researches of the 3D display technology in the real space.Experimental results show that the above-mentioned model analyses and system reseaches provides good guidelines for eliminating the phenomenon of the localized image areas are excessively brighter than the other areas due to duplicate mapping and overlap of voxels, overcoming the variations in image reconstruction effects with the changes of the image orientation, and reducing the exclusive spatial display error in 3D display.