• Title/Summary/Keyword: Parallel Projection

Search Result 116, Processing Time 0.028 seconds

Realtime Implementation Method for Perspective Distortion Correction (원근 왜곡 보정의 실시간 구현 방법)

  • Lee, Dong-Seok;Kim, Nam-Gyu;Kwon, Soon-Kak
    • Journal of Korea Multimedia Society
    • /
    • v.20 no.4
    • /
    • pp.606-613
    • /
    • 2017
  • When the planar area is captured by the depth camera, the shape of the plane in the captured image has perspective projection distortion according to the position of the camera. We can correct the distorted image by the depth information in the plane in the captured area. Previous depth information based perspective distortion correction methods fail to satisfy the real-time property due to a large amount of computation. In this paper, we propose the method of applying the conversion table selectively by measuring the motion of the plane and performing the correction process by parallel processing for correcting perspective projection distortion. By appling the proposed method, the system for correcting perspective projection distortion correct the distorted image, whose resolution is 640x480, as 22.52ms per frame, so the proposed system satisfies the real-time property.

James-Stein Type Estimators Shrinking towards Projection Vector When the Norm is Restricted to an Interval

  • Baek, Hoh Yoo;Park, Su Hyang
    • Journal of Integrative Natural Science
    • /
    • v.10 no.1
    • /
    • pp.33-39
    • /
    • 2017
  • Consider the problem of estimating a $p{\times}1$ mean vector ${\theta}(p-q{\geq}3)$, $q=rank(P_V)$ with a projection matrix $P_v$ under the quadratic loss, based on a sample $X_1$, $X_2$, ${\cdots}$, $X_n$. We find a James-Stein type decision rule which shrinks towards projection vector when the underlying distribution is that of a variance mixture of normals and when the norm ${\parallel}{\theta}-P_V{\theta}{\parallel}$ is restricted to a known interval, where $P_V$ is an idempotent and projection matrix and rank $(P_V)=q$. In this case, we characterize a minimal complete class within the class of James-Stein type decision rules. We also characterize the subclass of James-Stein type decision rules that dominate the sample mean.

Noise Properties for Filtered Back Projection in CT Reconstruction (필터보정역투영 CT 영상재구성방법에서 잡음 특성)

  • Chon, Kwonsu
    • Journal of the Korean Society of Radiology
    • /
    • v.8 no.6
    • /
    • pp.357-364
    • /
    • 2014
  • The filtered back projection in the image reconstruction algorithms for the clinic computed tomography system has been widely used. Noise of the reconstructed image was examined under the input noise for parallel and fan beam geometries. The reconstruction images of $512{\times}512$ size were carried out under 360 and 720 projection by the Visual C++ for parallel beam and fan beam, respectively, and those agreed with the original Shepp-Logan head phantom very much. Noise was generated because of intrinsic restriction (finite number of projections) for the image reconstruction algorithm, filtered back projection, when no input noise was applied. Because the result noise was rapidly increased under 0.5% input noise ratio, technologies for reducing noise in CT system and image processing is important.

Parallel Implementation of Radon Transform on TMS320C80-based System (TMS320C80시스템에서 Radon 변환의 병렬 구현)

  • 송정호;성효경최흥문
    • Proceedings of the IEEK Conference
    • /
    • 1998.10a
    • /
    • pp.727-730
    • /
    • 1998
  • In this paper, we propose an implementation of an efficient parallel Radon transform on TMS320C80-based system. For an N$\times$N SAR image, we can obtain O(NM/p) of the conventional parallel Radon transform, by representing the projection patterns in Radon space variables instead of the image space variables, and pipelining the algorithm, where p is the number of processors and M is the number of projection angles. Also, we can reduce the time for the dynamic load distribution among the nodes and the communication overheads of accessing the global memories, by pipelining the memory and processing operations by using tripple buffer structure. Experimental results show an efficient parallel Radon transform of speedup Sp=3.9 and efficiency E=97.5% for 256$\times$256 image, when implemented on TMS320C80 composed of four parallel slave processors with three memory blocks.

  • PDF

POSITIVE INTERPOLATION ON Ax = y AND AX = Y IN ALG$\mathcal{L}$

  • Kang, Joo-Ho
    • Honam Mathematical Journal
    • /
    • v.31 no.2
    • /
    • pp.259-265
    • /
    • 2009
  • Let $\mathcal{L}$ be a subspace lattice on a Hilbert space $\mathcal{H}$. Let x and y be vectors in $\mathcal{H}$ and let $P_x$ be the projection onto sp(x). If $P_xE$ = $EP_x$ for each E ${\in}\;\mathcal{L}$, then the following are equivalent. (1) There exists an operator A in Alg$\mathcal{L}$ such that Ax = y, Af = 0 for all f in $sp(x)^{\perp}$ and A ${\geq}$ 0. (2) sup ${\frac{{\parallel}E^{\perp}y{\parallel}}{{\parallel}E^{\perp}x{\parallel}}:E{\in}\mathcal{L}}$ < ${\infty}$ < x, y > ${\geq}$ 0. Let X and Y be operators in $\mathcal{B}(\mathcal{H})$. Let P be the projection onto $\overline{rangeX}$. If PE = EP for each E ${\in}\;\mathcal{L}$, then the following are equivalent: (1) sup ${\frac{{\parallel}E^{\perp}Yf{\parallel}}{{\parallel}E^{\perp}Xf{\parallel}}:f{\in}\mathcal{H},E{\in}\mathcal{L}}$ < ${\infty}$ and < Xf, Yf > ${\geq}$ 0 for all f in H. (2) There exists a positive operator A in Alg$\mathcal{L}$ such that AX = Y.

Estimators Shrinking towards Projection Vector for Multivariate Normal Mean Vector under the Norm with a Known Interval

  • Baek, Hoh Yoo
    • Journal of Integrative Natural Science
    • /
    • v.11 no.3
    • /
    • pp.154-160
    • /
    • 2018
  • Consider the problem of estimating a $p{\times}1$ mean vector ${\theta}(p-r{\geq}3)$, r = rank(K) with a projection matrix K under the quadratic loss, based on a sample $Y_1$, $Y_2$, ${\cdots}$, $Y_n$. In this paper a James-Stein type estimator with shrinkage form is given when it's variance distribution is specified and when the norm ${\parallel}{\theta}-K{\theta}{\parallel}$ is constrain, where K is an idempotent and symmetric matrix and rank(K) = r. It is characterized a minimal complete class of James-Stein type estimators in this case. And the subclass of James-Stein type estimators that dominate the sample mean is derived.

An improvement of estimators for the multinormal mean vector with the known norm

  • Kim, Jaehyun;Baek, Hoh Yoo
    • Journal of the Korean Data and Information Science Society
    • /
    • v.28 no.2
    • /
    • pp.435-442
    • /
    • 2017
  • Consider the problem of estimating a $p{\times}1$ mean vector ${\theta}$ (p ${\geq}$ 3) under the quadratic loss from multi-variate normal population. We find a James-Stein type estimator which shrinks towards the projection vectors when the underlying distribution is that of a variance mixture of normals. In this case, the norm ${\parallel}{\theta}-K{\theta}{\parallel}$ is known where K is a projection vector with rank(K) = q. The class of this type estimator is quite general to include the class of the estimators proposed by Merchand and Giri (1993). We can derive the class and obtain the optimal type estimator. Also, this research can be applied to the simple and multiple regression model in the case of rank(K) ${\geq}2$.

Locally Initiating Line-Based Object Association in Large Scale Multiple Cameras Environment

  • Cho, Shung-Han;Nam, Yun-Young;Hong, Sang-Jin;Cho, We-Duke
    • KSII Transactions on Internet and Information Systems (TIIS)
    • /
    • v.4 no.3
    • /
    • pp.358-379
    • /
    • 2010
  • Multiple object association is an important capability in visual surveillance system with multiple cameras. In this paper, we introduce locally initiating line-based object association with the parallel projection camera model, which can be applicable to the situation without the common (ground) plane. The parallel projection camera model supports the camera movement (i.e. panning, tilting and zooming) by using the simple table based compensation for non-ideal camera parameters. We propose the threshold distance based homographic line generation algorithm. This takes account of uncertain parameters such as transformation error, height uncertainty of objects and synchronization issue between cameras. Thus, the proposed algorithm associates multiple objects on demand in the surveillance system where the camera movement dynamically changes. We verify the proposed method with actual image frames. Finally, we discuss the strategy to improve the association performance by using the temporal and spatial redundancy.

A Rectification of Stereo Pairs Using Perspective Projection Matrices Estimated (추정된 원근투영행렬을 이용한 스테레오 영상 평행화에 관한 연구)

  • 정효림;이종수
    • Proceedings of the IEEK Conference
    • /
    • 2002.06d
    • /
    • pp.125-128
    • /
    • 2002
  • This paper propose a rectification technique by applying the Projection matrices derived from perspective projection matrices estimated from self-calibrated stereo image pairs. The derivation is made such that two epipolar lines are in parallel. Rectified images are generated by reprojecting corresponding image points. For the performance analysis of this technique, vertical coordinates of rectified points are compare to those obtained by the technique[3].

  • PDF

Parallel Processing of Multi-Core Processor and GPUs in Projection Step for Efficient Fluid Simulation (효율적인 유체 시뮬레이션을 위한 투영 단계에서의 멀티 코어 프로세서와 그래픽 프로세서의 병렬처리)

  • Kim, Sun-Tae;Jung, Hwi-Ryong;Hong, Jeong-Mo
    • The Journal of the Korea Contents Association
    • /
    • v.13 no.6
    • /
    • pp.48-54
    • /
    • 2013
  • In these days, the state-of-art technologies employ the heterogeneous parallelization of CPU and GPU for fluid simulations in the field of computer graphics. In this paper, we present a novel CPU-GPU parallel algorithm that solves projection step of fluid simulation more efficiently than existing sequential CPU-GPU processing. Fluid simulation that requires high computational resources can be carried out efficiently by the proposed method.