全球有限区通用数值预报模式是21世纪数值预报模式的发展趋势,为此"十五"期间中国气象局发展了一个GRAPES(global/regional assimilation and prediction system)全球有限区多尺度非静力数值预报模式.为了验证GRAPES模式方案...全球有限区通用数值预报模式是21世纪数值预报模式的发展趋势,为此"十五"期间中国气象局发展了一个GRAPES(global/regional assimilation and prediction system)全球有限区多尺度非静力数值预报模式.为了验证GRAPES模式方案设计的科学性、程序编写的正确性,针对模式的特点设计了一套完整的理想试验方案来对GRAPES动力模式的性能进行检验,包括用于检验中尺度模式的密度流和三维地形波试验;用于检验近极地半拉格朗日上游点和极区离散方案正确性的越极地气流试验等.密度流试验显示模式框架对精细尺度的非线性流及其瞬变特征有较强的模拟能力;三维地形波试验说明GRAPES模式动力框架能够较好地模拟气流过山时重力内波的水平与垂直传播.而越极地气流试验验证了模式对极地半拉格朗日上游点及近极地的离散处理是正确的.实际个例试验表明,GRAPES全球模式对影响中国夏季的大尺度环流形势有较好的预报能力.展开更多
Shape-from-shading(SFS) is one of the important approaches of 3-D surface reconstruction in computer vision. Since reflectance map equation in SFS is a nonlinear partial differential equation(PDE) with two unknown var...Shape-from-shading(SFS) is one of the important approaches of 3-D surface reconstruction in computer vision. Since reflectance map equation in SFS is a nonlinear partial differential equation(PDE) with two unknown variables, SFS with one image is ill-posed in mathematical sense. A linear perspective SFS method with two images is proposed to deal with the problem. We assume that two images with different light source directions are captured firstly. Orthogonal projection is not as accurate as perspective one to simulate imaging processes. Two reflectance map equations are established based on the Lambertian model under perspective projection, and the equations are further transformed into one linear PDE. Then the iterative semi-Lagrangian algorithm is used to approximate the solution. Finally, 3-D height values of pixel points in imaging planes are solved by the numerical interpolation method. Experimental results of both hemisphere and complex surfaces show that the proposed method can reconstruct surfaces accurately.展开更多
文摘全球有限区通用数值预报模式是21世纪数值预报模式的发展趋势,为此"十五"期间中国气象局发展了一个GRAPES(global/regional assimilation and prediction system)全球有限区多尺度非静力数值预报模式.为了验证GRAPES模式方案设计的科学性、程序编写的正确性,针对模式的特点设计了一套完整的理想试验方案来对GRAPES动力模式的性能进行检验,包括用于检验中尺度模式的密度流和三维地形波试验;用于检验近极地半拉格朗日上游点和极区离散方案正确性的越极地气流试验等.密度流试验显示模式框架对精细尺度的非线性流及其瞬变特征有较强的模拟能力;三维地形波试验说明GRAPES模式动力框架能够较好地模拟气流过山时重力内波的水平与垂直传播.而越极地气流试验验证了模式对极地半拉格朗日上游点及近极地的离散处理是正确的.实际个例试验表明,GRAPES全球模式对影响中国夏季的大尺度环流形势有较好的预报能力.
基金supported by the National Natural Science Foundation of China(61005015)the Third National Post-Doctoral Special Foundation of China(201003280)
文摘Shape-from-shading(SFS) is one of the important approaches of 3-D surface reconstruction in computer vision. Since reflectance map equation in SFS is a nonlinear partial differential equation(PDE) with two unknown variables, SFS with one image is ill-posed in mathematical sense. A linear perspective SFS method with two images is proposed to deal with the problem. We assume that two images with different light source directions are captured firstly. Orthogonal projection is not as accurate as perspective one to simulate imaging processes. Two reflectance map equations are established based on the Lambertian model under perspective projection, and the equations are further transformed into one linear PDE. Then the iterative semi-Lagrangian algorithm is used to approximate the solution. Finally, 3-D height values of pixel points in imaging planes are solved by the numerical interpolation method. Experimental results of both hemisphere and complex surfaces show that the proposed method can reconstruct surfaces accurately.
