For a multiview three-dimensional (3-D) display system using a two-dimensional (2-D) flat panel display, it is very important to attach accurately an optical plate such as a parallax barrier and a lenticular lens sheet onto a 2-D display panel for the best quality of 3-D images. In most practical cases, however, misalignment occurs since it is too difficult to align perfectly in assembly process. In general, angular misalignment results in the deterioration of 3-D image quality by some increase of crosstalk, so that the resulting 3-D images are even distorted as tilted ones. To correct distorted 3-D images, we propose a method to skew 3-D objects before each image for multiviews is taken by multiple cameras. For this, a formula is derived to determine the amount of skewing 3-D objects. And by using it, some experimental results are shown that distorted 3-D images in a misaligned multiview 3-D display system are completely corrected. Since skewing 3-D objects implies a coordinate transformation of 3-D space, this method can be also used in the manipulation of 3-D image data obtained from a depth camera in order to correct the distorted 3-D images caused by angular misalignment.
Tensor display is an option in glasses-free three-dimensional (3-D) display technology. An initial solution has to be set to decompose the light-field information to be represented by the system. We have analyzed the impact of the initial guess on the multiplicative update rules in terms of peak signal-to-noise ratio, and proposed a method based on depth map estimation from an input light field. Results from simulations were obtained and compared with previous literature. In our sample, the initial values used have a large influence on results and convergence to a local minimum. The quality of the output stabilizes after a certain number of iterations, suggesting that a limit on such numbers should be imposed. We show that the proposed methods outperform the pre-existing ones.
Object tracking is an important problem in computer vision research. Among the difficulties of object tracking, the problem of partial and full occlusion is one of the most serious and challenging problems. To address the problem, we proposed methods to object tracking using plenoptic image sequences. Our methods take advantage of the refocusing capability that plenoptic imaging provides. The proposed methods input the sequences of focal stacks constructed by applying the refocusing algorithm on the plenoptic image sequences. The proposed image selection algorithms select the sequence of optimal images that can maximize the tracking accuracy from the sequence of focal stacks. Focus measure approach and confidence measure approach were proposed as image selection methods and both approaches were validated by the experiments using three groups of plenoptic image sequences that include heavily occluded target objects. The experimental results showed that the proposed methods were promising comparing to the conventional 2-D object tracking algorithms.
Several wavefront printers have been recently proposed. Since the printers can record an arbitrary computer-generated wavefront, they are expected to be useful for fabricating complex mirror arrays used in front projection 3-D screens without using real existing optics. We prototyped two transparent reflective screens using our hologram printer in experiments. These screens could compensate for a spherically distorted reference wave caused by a short projection distance to obtain an ideal reference wave. Owing to the use of the wavefront-printed screen, the 3-D display was simply composed of a normal 2-D projector and a screen without using extra optics. In our binocular system, reflected light rays converged to the left and right eyes of the observer and the crosstalk was less than 8%. In the light field system, the reflected light rays formed a spatially sampled light field and focused a virtual object in a depth range of ±30 mm with a ±13.5-deg viewing angle. By developing wavefront printing technology, a complex optics array may easily be printed by nonprofessionals for optics manufacturing.