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In this paper, a new pipeline of structure-from-motion for ground-view images is proposed that uses feature points on an aerial image as references for removing accumulative errors. The challenge here is to design a method for discriminating correct matches from unreliable matches between ground-view images and an aerial image. If we depend on only local image features, it is not possible in principle to remove all the incorrect matches, because there frequently exist repetitive and/or similar patterns, such as road signs. In order to overcome this difficulty, we employ geometric consistency-verification of matches using the RANSAC scheme that comprises two stages: (1) sampling-based local verification focusing on the orientation and scale information extracted by a feature descriptor, and (2) global verification using camera poses estimated by the bundle adjustment using sampled matches. [ABSTRACT FROM AUTHOR]

Background The integration of EEG recordings and transcranial neuromodulation has provided a useful construct for noninvasively investigating the modification of human brain circuit activity. Recent evidence has demonstrated that focused ultrasound can be targeted through the human skull to affect the amplitude of somatosensory evoked potentials and its associated spectral content. Objective/hypothesis The present study tests whether focused ultrasound transmitted through the human skull and targeted to somatosensory cortex can affect the phase and phase rate of cortical oscillatory dynamics. Methods A computational model was developed to gain insight regarding the insertion behavior of ultrasound induced pressure waves in the human head. The instantaneous phase and phase rate of EEG recordings before, during, and after transmission of transcranial focused ultrasound (tFUS) to human somatosensory cortex were examined to explore its effects on phase dynamics. Results Computational modeling results show the skull effectively reinforces the focusing of tFUS due to curvature of material interfaces. Neurophysiological recordings show that tFUS alters the phase distribution of intrinsic brain activity for beta frequencies, but not gamma. This modulation was accompanied by a change in phase rate of both beta and gamma frequencies. Additionally, tFUS modulated phase distributions in the beta band of early sensory-evoked activity but did not affect late sensory-evoked activity, lending support to the spatial specificity of tFUS for neuromodulation. This spatial specificity was confirmed through an additional experiment where the ultrasound transducer was moved 1 cm laterally from the original cortical target. Conclusions Focused ultrasonic energy can alter EEG oscillatory dynamics through local mechanical perturbation of discrete cortical circuits. [ABSTRACT FROM AUTHOR]

Background: A superporous (85%) hydroxyapatite (HA) block was recently developed to improve osteoconductivity, but it was often not clinically successful when used to treat periodontal osseous defects. The primary purpose of this study is to develop a clinically applicable tissue-engineered bone substitute using this HA block and human alveolar periosteum-derived cells. Methods: Commercially available superporous HA blocks were acid treated and subjected to a three-dimensional (3D) culture for periosteal cell cultivation. Cells in the pore regions of the treated HA block were observed on the fracture surface by scanning electron microscopy. After osteogenic induction, the cell-HA complexes were implanted subcutaneously in nude mice. Osteoid formation was histologically evaluated. Results: Acid treatment enlarged the interconnections among pores, resulting in the deep penetration of periosteal cells. Under these conditions, cells were maintained for >2 weeks without appreciable cell death in the deep pore regions of the HA block. The cell-HA complexes that received in vitro osteogenic induction formed osteoids in pore regions of the treated HA blocks in vivo. In contrast, most pore regions in the nonpretreated, cell-free HA blocks that were evaluated in vivo remained cell free. Conclusions: Our findings suggest that an acid-treated HA block could function as a better scaffold for the 3D high-density culture of human periosteal cells in vitro, and this cell-HA complex had significant osteogenic potential at the site of implantation in vivo. Compared with the cell-free HA block, our cell-HA complex using periosteal cells, which are the most accessible for clinical periodontists, showed promising results as a bone substitute in periodontal regenerative therapy. [ABSTRACT FROM AUTHOR]

This paper proposes a method to render free viewpoint images from omnidirectional videos using a deformable 3-D mesh model. In the proposed method, a 3-D mesh is placed in front of a virtual viewpoint and deformed by using the pre-estimated omnidirectional depth maps that are selected on the basis of position and posture of the virtual viewpoint. Although our approach is fundamentally based on the model-based rendering approach that renders a geometrically correct virtualized world, in order to avoid the hole problem, we newly employ a viewpoint-dependent deformable 3-D model instead of the use of a unified 3-D model that is generally used in the model based rendering approach. In experiments, free-viewpoint images are generated from the omnidirectional video captured by an omnidirectional multi camera system to show the feasibility of the proposed method for walk-through applications in the virtualized environment. [ABSTRACT FROM AUTHOR]

Camera parameter recovery from an image sequence is very important in many applications such as 3D model reconstruction, object recognition, robot navigation, and mixed reality. However, there is a problem concerning the precision in camera parameter estimation from the image sequence, because feature tracking errors and estimation errors are accumulated. In this paper, we propose a camera parameter estimation method which is based on using a number of markers with known 3D position, color, and shape, as well as natural features. Initially, the camera parameters and 3D positions of natural features are estimated efficiently in every frame by tracking both these markers and natural features. The accumulation of estimated errors is then minimized by specifying additional markers in some frames of input and optimizing parameters globally through the whole input. In the experiments, some results of 3D reconstruction show the validity of the proposed method. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(8): 12–20, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10702 [ABSTRACT FROM AUTHOR]