一种新的影像位姿直接估计方法     

李艳焕  徐振亮  邵良杉 《测绘通报》2017,(6):17-20

针对影像位姿耦合不易直接求解的问题,建立了一种高精度分层位姿参数估计的方法。首先,通过选择3点构成面积最大的像点对应的物点作为基点,经投影方程的改化形式方程,得到估计深度及平移信息;然后利用旋转矩阵保范性获得相机外参线元素尺度参数;最后,将问题转化为由向量估计旋转关系问题,利用Procrustes理论得到外参角元素的最佳估值。该方法可有效解决该深度与耦合位姿参数难以处理的问题。试验证明,此方法确定的位姿参数估计模型形式简洁,容易收敛,参数估计精度较直接对投影矩阵分解方法质量要高。  相似文献   

Fast BDS Positioning Convergence Based on the Contribution of GPS Observations     

Yan Xu  Guochang Xu  Ling Zhang  Harald Schuh 《Marine Geodesy》2017,40(6):404-415

Comparing to single BeiDou Navigation Satellite System (BDS) Precise Point Positioning (PPP), a method which can more quicklydetermine the ambiguity parameters of BDS through applying the contribution of GPS observations is proposed and analyzed in this article. The numerical examples and analysis show that the ionosphere-free ambiguities of BDS satellites can be determined and converged more quickly because of the contribution of GPS observations. The average improvement of the convergent speed of positioning is 18.5% and its positioning accuracy in N, E, and U components are improved by 29.4, 30.3, and 34.4%, respectively, with the contribution of the a priori coordinates obtained from GPS observations. This method is useful for single BDS system positioning when there is a priori information provided by GPS or other sensors which be replaced by and can be applied at the beginning of the computation.  相似文献   

A three dimensional model for water-sediment movement     

LIU Cheng  SHEN Yong-Ming 《国际泥沙研究》2010,25(1)

A three-dimensional k-ε-Ap two-fluid turbulence model is proposed to study liquid-particle two-phase flow and bed deformation.By solving coupled liquid-phase and solid-phase governing equations in a finite-volume method,the model can calculate the movement of both water and sediment.The model was validated by water-sediment transport in a 180° channel bend with a movable bed.The validation concerns two-phase time-averaged velocities,bed deformation,water depth,depth-averaged streamwise velocity,cross-stream bed profiles,and two-phase secondary flow velocity vectors.The agreement between numerical results and experimental results was generally good.The comparisons of the numerical results of different models show that the three-dimensional k-ε-Ap two-fluid turbulence model has a relatively higher accuracy than one-fluid model.  相似文献   

Scattering of SH waves by a scalene triangular hill   总被引：1，自引：1，他引：0  

Shuzhi?Lin  Faqiang?QiuEmail author  Diankui?Liu 《地震工程与工程振动(英文版)》2010,9(1):23-38

<正>The influence of local landforms on ground motion is an important problem.The antiplane response of a scalene triangular hill to incident SH waves is studied in this paper by using a complex function,moving coordinates and auxiliary functions.First,the model is divided into two domains:a scalene triangular hill with a semi-circular bottom;and a half space with a semi-circular canyon.Wave functions that satisfy the zero-stress condition at the triangular wedges and at the horizontal surface are constructed in both domains.Then,considering the displacement continuity and stress equilibrium, algebraic equations are established.Finally,numerical examples are provided to illustrate the influence of the geometry of the hill and the characteristics of the incident waves on the ground motions.  相似文献   

浅谈宁安城际铁路坐标系统与芜湖当地坐标系统的转换     

李华平  张红梅  章捷 《安徽地质》2009,19(4):311-313

在工程测量中我们会遇到很多关于两个坐标系统之间的坐标转换,为了更好的解决这个问题,该文通过宁安城际铁路工程实例,运用Powercoor转换软件,快速计算实现铁路系统北京54坐标与芜湖当地坐标之间的转换。  相似文献   

Fast transform from geocentric to geodetic coordinates   总被引：3，自引：0，他引：3  

T. Fukushima 《Journal of Geodesy》1999,73(11):603-610

 A new iterative procedure to transform geocentric rectangular coordinates to geodetic coordinates is derived. The procedure solves a modification of Borkowski's quartic equation by the Newton method from a set of stable starters. The new method runs a little faster than the single application of Bowring's formula, which has been known as the most efficient procedure. The new method is sufficiently precise because the resulting relative error is less than 10⁻¹⁵, and this method is stable in the sense that the iteration converges for all coordinates including the near-geocenter region where Bowring's iterative method diverges and the near-polar axis region where Borkowski's non-iterative method suffers a loss of precision. Received: 13 November 1998 / Accepted: 27 August 1999  相似文献   

A new solution to the lagrange's case of the three‐body problem     

E. Piña 《Celestial Mechanics and Dynamical Astronomy》1999,74(3):163-174

The motion of three particles, interacting by gravitational forces, is studied in a new coordinate system given by the principal axes of inertia, as determined by Euler angles, and using the inertia principal moments and an auxiliar angle as coordinates. The solution to the particular Lagrange case of the three‐body problem is reviewed and solved in these new coordinates. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Numerical Modeling of the Hyperbolic Mild-Slope Equation in Curvilinear Coordinates   总被引：2，自引：0，他引：2  

佟飞飞  沈永明  唐军  崔雷 《中国海洋工程》2010,(4)

The mild-slope equation is familiar to coastal engineers as it can effectively describe wave propagation in nearshore regions. However,its computational method in Cartesian coordinates often renders the model inaccurate in areas with irregular shorelines,such as estuaries and harbors. Based on the hyperbolic mild-slope equation in Cartesian coordinates,the numerical model in orthogonal curvilinear coordinates is developed. The transformed model is discretized by the finite difference method and solved by th...  相似文献   

Applying invariant eigen-operator method to deriving normal coordinates of general classical Hamiltonian     

范洪义  陈俊华  袁洪春 《海洋学报(英文版)》2010,29(9)

For classical Hamiltonian with general form we find a new convenient way to obtain its normal coordinates, namely, let H be quantised and then employ the invariant eigen-operator (IEO) method (Fan et al. 2004 Phys. Lett. A 321 75) to derive them. The general matrix equation, which relies on M and L, for obtaining the normal coordinates of H is derived.  相似文献   

Finite volume approach for finite strain consolidation          下载免费PDF全文

Rakesh Pratap Singh  Chandra Shekhar Prasad Ojha  Mahendra Singh 《国际地质力学数值与分析法杂志》2016,40(1):117-140

The paper presents the finite volume formulation and numerical solution of finite strain one‐dimensional consolidation equation. The equation used in this study utilises a nonlinear continuum representation of consolidation with varying compressibility and hydraulic conductivity and thus inherits the material and geometric nonlinearity. Time‐marching explicit scheme has been used to achieve transient solutions. The nonlinear terms have been evaluated with the known previous time step value of the independent variable, that is, void ratio. Three‐point quadratic interpolation function of Lagrangian family has been used to evaluate the face values at discrete control volumes. It has been shown that the numerical solution is stable and convergent for the general practical cases of consolidation. Performance of the numerical scheme has been evaluated by comparing the results with an analytical solution and with the piecewise piecewise‐linear finite difference numerical model. The approach seems to work well and offers excellent potential for simulating finite strain consolidation. Further, the parametric study has been performed on soft organic clays, and the influence of various parameters on the time ate consolidation characteristics of the soil is shown. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献