[Show abstract][Hide abstract] ABSTRACT: In this paper, based on the analysis of the UCA
beamforming algorithm, an efficient SDMA scheme using the
uniform circular array (UCA) with 8 elements is proposed. As
the scheme devised, the cell is sectored by 2 crossed beam groups
formed by UCA and the large elevation area of the cell is
covered by UCA omni-directional pattern. With SDMA
technique applied in the sectors, the cellular capacity can be
increased nearly 5 times with low co-channel interference. The
simulation results verify that, the scheme is of good feasibility in
implementation and has a practical worth to be applied in hot
[Show abstract][Hide abstract] ABSTRACT: The existing cognitive network can not provide the spatial sectors for a cell, since the base-station (BS) has one omni-directional antenna. Thus it is impossible for a base-band channel to be shared by several mobile stations(MSs) with one omni-directional antenna. To solve the problem, this paper proposes the spatial multiplexing algorithms for transmitter and receiver of cognitive BS. In the proposed scheme, the cognitive BS has a uniform circular array (UCA) with 8 elements, it can provide five nearly orthogonal sectors for MSs, and a base-band channel can be shared by 5 sectors, but the MS has one omni-directional antenna only, and simple transmitter and receiver. The experimental results verify that the proposed algorithms are able to increase the cellular capacity to nearly 5 times with low co-channel interference, and the co-channel interference also can be canceled by LDPC codec.
[Show abstract][Hide abstract] ABSTRACT: 3D reconstruction is an important technique in the domain of computer vision. The existing systems of 3D reconstruction are often built on specialized hardware such as structured light or laser scanner with high cost. And some systems require intricate calibration procedures using complex calibration objects. These are not practical to reconstruct the 3D model of an arbitrary scene. In this paper, a flexible method of 3D reconstruction based on uncalibrated image sequence is proposed. This system consist a series of processes such as feature points extraction and match, projective reconstruction, self-calibration, dense match, and finally the dense surface of 3D model can be reconstructed. Experimental results prove that this method is practical and has higher precision.
[Show abstract][Hide abstract] ABSTRACT: 3D reconstruction is an important technique in the field of computer vision. The traditional 3D reconstruction technology involves the self-calibration method basing on dual absolute quadric. However, some drawbacks in this method cause this technology less robust. First, usually the solution of the dual quadric matrix can not satisfy the positive-definiteness condition caused by loud noise in data; second, if the motion of the camera is too restricted, the calibration degeneracy will turn up causing the reconstruction failed. To these questions, we design a new method for calibrating the camera using the camera pure rotating calibration and decomposing the essential matrix. So, the metric structure can be got directly avoiding the less robustness caused by self-calibration. Experiments show that, using this method the reconstruction has an efficient result and the procedure is convenient.
[Show abstract][Hide abstract] ABSTRACT: An improved method based on two layers image retrieval is proposed. The first layer retrieval extract edge of wavelet modulus maxima and use 7 moment invariants as the shape features and the averages and variances of the multi-scaling 2-D wavelet decomposition coefficients as the synthesis eigenvector. The second one consists of the local color histograms. Difference weights are assigned to every block according to the importance of its spatial distribution. This method combines the advantages of the 7 moment invariants and the local spatial features, thereby achieving the better retrieval performance.
[Show abstract][Hide abstract] ABSTRACT: A new method based on two layers image retrieval is proposed. The first layer retrieval feature is global color histogram and the second one consists of the local color histogram, the averages and variances of the multi-scaling 2D wavelet decomposition coefficients. Difference weights are assigned to every block according to the importance of its spatial distribution. This method combines the advantages of the global and the local color histogram, thereby achieving the better retrieval performance.
[Show abstract][Hide abstract] ABSTRACT: In this paper, a flexible method of camera calibration is proposed: Firstly, calibrate the intrinsic camera parameters including a coefficient of radial distortion by moving a ID object (points aligned on a line) with a invisible fixed point; Secondly, calibrate the extrinsic camera parameters relative to a given world coordinate system using the four-point object which right-angle shaped involving three collinear points and one point on the perpendicular direction. The calibration objects are simple to make and can be perfectly observed from any orientations. With these merits, the method is very practical to calibrate the multi-camera systems. Experimental results show that, the calibration is of high precision and the procedure is very convenient.