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Yuji IWAHORI Robert J. WOODHAM Hidekazu TANAKA Naohiro ISHII
This paper describes a new method to determine the 3-D position coordinates of a Lambertian surface from four shaded images acquired with an actively controlled, nearby moving point light source. The method treats both the case when the initial position of the light source is known and the case when it is unknown.
This paper proposes a novel cache architecture for low power consumption, called "Adaptive Way-Predicting Cache (AWP cache)." The AWP cache has multi-operation modes and dynamically adapts the operation mode based on the accuracy of way-prediction results. A confidence counter for way prediction is implemented to each cache set. In order to analyze the effectiveness of the AWP cache, we perform a SRAM design using 0.18 µm CMOS technology and cycle-accurate processor simulations. As the results, for a benchmark program (179.art), it is observed that a performance-aware AWP cache reduces the 49% of performance overhead caused by an original way-predicting cache to 17%. Furthermore, a energy-aware AWP cache achieves 73% of energy reduction, whereas that obtained from the original way-predicting scheme is only 38%, compared to an non-optimized conventional cache. For the consideration of energy-performance efficiency, we see that the energy-aware AWP cache produces better results; the energy-delay product of conventional organization is reduced to only 35% in average which is 6% better than the original way-predicting scheme.
Yuji IWAHORI Robert J. WOODHAM Masahiro OZAKI Hidekazu TANAKA Naohiro ISHII
An implementation of photometric stereo is described in which all directions of illumination are close to and rotationally symmetric about the viewing direction. THis has practical value but gives rise to a problem that is numerically ill-conditioned. Ill-conditioning is overcome in two ways. First, many more than the theoretical minimum number of images are acquired. Second, principal components analysis (PCA) is used as a linear preprocessing technique to determine a reduced dimensionality subspace to use as input. The approach is empirical. The ability of a radial basis function (RBF) neural network to do non-parametric functional approximation is exploited. One network maps image irradiance to surface normal. A second network maps surface normal to image irradiance. The two networks are trained using samples from a calibration sphere. Comparison between the actual input and the inversely predicted input is used as a confidence estimate. Results on real data are demonstrated.
Yuji IWAHORI Hidekazu TANAKA Robert J. WOODHAM Naohiro ISHII
This paper proposes a new method to determine the shape of a surface by learning the mapping between three image irradiances observed under illumination from three lighting directions and the corresponding surface gradient. The method uses Phong reflectance function to describe specular reflectance. Lambertian reflectance is included as a special case. A neural network is constructed to estimate the values of reflectance parameters and the object surface gradient distribution under the assumption that the values of reflectance parameters are not known in advance. The method reconstructs the surface gradient distribution after determining the values of reflectance parameters of a test object using two step neural network which consists of one to extract two gradient parameters from three image irradiances and its inverse one. The effectiveness of this proposed neural network is confirmed by computer simulations and by experiment with a real object.
Eiji TOBA Junji KAZAMA Hidekazu TANAKA Toyonori NISHIMATSU Hiroaki AIZAWA Hiroaki ISHIZAWA
In this paper, we will report on a fiber optic oxygen sensor using fluorescence and its application to clinical examinations. It is based on fluorescence quenching. The quenching ratio of fluorescence is proportional to oxygen partial pressure by Stern-Volmer's formula in which oxygen concentration is estimated from measured emission intensity. We fabricated a microscopic luminous probe using a Solvent Green 5 doped plastic optical fiber coupler. The probes were demonstrated to have certain advantages for example they can be operated in both liquid and gas phases. And also, they are stable to pH and flow velocities. As a clinical application, the probe can reliably measure oxygen concentrations of whole blood in vivo. Moreover, we have clarified various characteristics of this probe.