Masami Yamasaki

Real-Time Observation of the Interaction between Flux Lines and Defects in a Superconductor by Lorentz Microscopy.

Flux lines in a Nb thin film at 4.5 K were observed by using a 300-kV field-emission transmission electron microscope equipped with a TV system. When the magnetic field applied to the film was suddenly changed, flux lines moved until arriving at an equilibrium state by hopping from one pinning center to another. Frame-by-frame observation of videotape recorded with a time resolution of 1/30 s revealed how individual flux lines behaved when they came across subgrain boundaries, and interacted with the boundaries.

41.2: Autostereoscopic Display Based on Enhanced Integral Photography Using Overlaid Multiple Projectors

We constructed an autostereoscopic display based on enhanced IP using overlaid multiple projectors. The display provides autostereoscopic images whose resolution is greater than SVGA in an 800 by 400 mm area. Tilting the display surface increases the depth of the autostereoscopic images. We also constructed equipment for calibrating the display.

Full-parallax autostereoscopic display with scalable lateral resolution using overlaid multiple projection

— A method to increase the viewing resolution of an autostereoscopic display without increasing the density of microlenses is proposed. Multiple projectors are used for the projection images to be focused and overlaid on a common plane in the air behind the microlens array. The multiple overlaid projection images yield multiple light spots inside the region of each elemental lenslet of the microlens array. This feature provides scalable high-resolution images by increasing the number of projectors. Based on the proposed method, a prototype display that includes 15 projectors was designed and built. 3-D images were successfully reproduced on the prototype display with full parallax and a wide viewing angle of 70°.

Intra-operative guidance with real-time information of open MRI and manipulators using coordinate-integration module

Assuming the surgery under open magnetic resonance imaging (MRI) equipment with manipulators, we developed the coordinate-integration module and the real-time functions that could display the manipulators position on the volume data of MRI and could obtain the cross-section images of MRI at the manipulators position. The small field of view from an endoscope is the problem in most of the minimally invasive surgeries with manipulators. Therefore, we propose an endoscopic surgery with manipulators under open MRI equipment. The coordinate-conversion parameters were calculated in the coordinate-integration module by calibration with an optical tracking system and markers. The delay of the manipulator-position display on the volume data was approximately within 0.5 second though it depended on the amount of the volume data. We could also obtain the cross-section images of MRI at the manipulators position using the information from the coordinate-integration module. With these functions, we can cope with the change of the organ shape during surgery with the guidance based on the individual information. Furthermore, we can use the manipulator as an MRI probe to define cross-section position like an ultrasonic probe.

A video-based virtual reality system

We introduce a new environment to make and play interactive contents with more than video game quality. The system consists of a projector array, a viewer and an editor for the special contents. The projector array projects multiple digital images seamlessly both in time and space, thus a very high quality video projection system. The viewer features a function to composite a passive video and interactive CG in real time. The editor is a high-end non-linear editing system combined with some new plug-in software to pre-compute the information necessary for real-time compositing. A new method of digital image recognition assisted by human operators is used. Unlike general purpose computer vision algorithms, it minimizes the error of 3D estimation at the compositing position. We call this approach V2R or the video-based virtual reality. It allows the operator to experience interactive communications with objects in a very high quality video.

High-density light field reproduction using overlaid multiple projection images

We propose a method to increase the viewing resolution of an autostereoscopic display without increasing the density of microlenses. Multiple projectors are used for the projection images to be focused and overlaid on a common plane in the air behind the microlens array. The multiple overlaid projection images yield multiple light spots inside the region of each elemental lenslet of the microlens array. This feature provides scalable high resolution images by increasing the number of projectors.

Interactive autostereoscopic display with 60 ray directions

We need to design some parameters to determine the specifications of the IP display. The parameters are lens pitch, pixel density of 2D display, lens focus, lens layout, color filter layout of the display, and so on. We think that the maximal spatial frequency and the number of rays are the most important properties needed to produce realistic autostereoscopic images. Therefore, we must decide which parameters to use to increase the number of rays and the maximal spatial frequency. The lens pitch usually determines the maximal spatial frequency of the IP displays. Whereas, the lens pitch and the pixel density of the 2D display determine the number of rays for IP displays. As there is a trade-off between the lens pitch and the pixel density, we must first decide minimum resolution of the IP display, and then decide the lens pitch and the pixel density of the 2D display.

Integral videography of high-density light field with spherical layout camera array

We propose a spherical layout for a camera array system when shooting images for use in Integral Videography (IV). IV is an autostereoscopic video image technique based on Integral Photography (IP) and is one of the preferred autostereoscopic techniques for displaying images. There are many studies on autostereoscopic displays based on this technique indicating its potential advantages. Other camera arrays have been studied, but their purpose addressed other issues, such as acquiring high-resolution images, capturing a light field, creating contents for non-IV-based autostereoscopic displays and so on. Moreover, IV displays images with high stereoscopic resolution when objects are displayed close to the display. As a consequence, we have to capture high-resolution images in close vicinity to the display. We constructed the spherical layout for the camera array system using 30 cameras arranged in a 6 by 5 array. Each camera had an angular difference of 6 degrees, and we set the cameras to the direction of the sphere center. These cameras can synchronously capture movies. The resolution of the cameras is a 640 by 480. With this system, we determined the effectiveness of the proposed layout of cameras and actually captured IP images, and displayed real autostereoscopic images.

Multi Screen Environment with a Motion Base

We put a motion base in a cubicle where three walls and the floor are video screens. The motion base works in two ways to enhance immersive feeling of the player. Firstly, it adds physical acceleration as most simulation rides do. Secondly, it reduces the discontinuity of an image on the multi screen system. Two planar screens placed at an angle generally have a problem that the image over the two screens does not look continuous at the seam of the screens unless the image is seen at one particular point where the perspective transformation was made. In the conventional systems, the position of the players head is tracked by sensors, then the image is rendered using the senced head position as the image viewpoint. Because of the inherent delay from the head motion to the appearance of the rendered image, the player is often distracted by the above discontinuity as well as by motion sickness. We introduce a method to anticipate the forecoming head motion which will be caused by the acceleration of the motion base. Then each image frame is rendered at the corresponding ideal viewpoint and displayed in a synchronized way with the base motion. This new control method substantially reduces the above problem when the player can change his/her head position only through driving operations for a vehicle.

The Lower Bound of the Capacity for a Neural Network with Multiple Hidden Layers

We show the lower bound of the capacity of a hierarchical neural network, having multiple hidden layers whose node unit takes the value of a real number between zero and one as the output of a sigmoid function. It is shown that \(n.\left \lceil \frac{h_1}{2} \right \rceil+\left \lfloor \frac{h_1}{2} \right \rfloor\cdot \left \lceil \frac{h_2}{2}-1 \right \rceil+\cdots +\left \lfloor \frac{h_{N-1}}{2} \right \rfloor\cdot\left \lceil \frac{h_N}{2}-1 \right \rceil\) examples in the general position (i.e. no subset of n or less input vectors degenerate) can be memorized by the network which has n input units in the input layer, hl hidden units in the l-th layer of N hidden layers, and a single output unit in the output layer.