Analyzing human motion, including tracking and pose estimation, is a major topic in computer vision. Many methods have been developped in the past and will be developped in the future. To have a systematic and quantitative evaluation of such methods, ground truth data of the 3D human motion is scientifically required. Some publicly available data sets exist, like HumanEva, that provide synchronized video sequences with detailed ground truth 3D data for scenes limited to only a single person. However, for multiple persons, such a data set currently does not exist. In this paper, we present the Utrecht Multi-Person Motion (UMPM) benchmark, which includes synchronized motion capture data and video sequences from multiple viewpoints for multi-person motion including multi-person interaction. The data set is available to the research community to promote research in multi-person articulated human motion analysis. This paper describes the design of the benchmark, the technical problem solutions, and the resulting data sets.
The rigorous coupled-wave analysis (RCWA) is a method to compute diffraction of a field by a given grating structure. Within various applications, such as metrology, it is important to know how the field reacts to small perturbations in the grating. This behavior can be expressed by the field derivatives with respect to a certain parameter. Approximations of these derivatives can be found by using finite differences where the field is computed for a neighboring value of the parameter, and the difference gives the derivative. Unfortunately, RCWA involves solving eigenvalue systems that are computationally expensive. Therefore, a faster alternative is given that computes the derivatives by straightforward differentiation of the relations within RCWA. Solving additional eigensystems is replaced by finding derivatives of eigenvalues and eigenvectors, which is less computationally expensive.
Summary. Diffraction gratings are often used in optical metrology. When an electromagnetic wave is incident on a grating, the periodicity of the grating causes a multiplicity of diffraction orders. In many metrology applications one needs to know the diffraction efficiency of these orders. Since the period of a grating is often of the same order of magnitude as the wavelength, it is needed to solve Maxwell's equations rigorously in order to obtain these diffraction efficiencies. Two of those methods are the rigorous coupled-wave analysis (RCWA) and the C method. In this paper a comparison is made between RCWA and the C method with respect to accuracy and speed. Restrictions are made to one-interface problems, which means that only two media are involved separated by one interface, and only gratings are considered with a periodicity in only one direction.
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