Volume 79, Issue 4 -

The visual analysis of human activities is gaining importance for more and more technical applications. A method for video-based motion capturing by tracking motion features is proposed. Movement is detected by applying spatio-temporal filtering to an image sequence. The resulting motion features are then tracked over time using motion and color cues. This yields feature trajectories which are utilized for modeling and recognition of various action classes.

The stitching approach which was developed for the sphere interferometer of the Physikalisch-Technische Bundesanstalt provides the capability to reconstruct the real form of a sphere as a topography of radii instead of diameters. A model based on spherical harmonics in which the lateral resolution of the topography is mainly constrained by the available computer memory was already presented. As a remedy an interpolation grid can be used in a modification of the model. An overview of both variants of the model is presented.

An new discrimination method for distinguishing materials [1] is introduced using the normalized cross-correlation coefficient which is implemented optically as a similarity measure. In the theoretical part of the paper a measurement equation and an explicit expression for the signal-to-noise ratio (SNR) are derived. The theory is applied in an experiment in which metameric colors are to be distinguished. Finally the results are compared with simulated values.

Applications of satellite localisation for railways have to fulfil high safety requirements. This leads to a qualification of their measurement and reliability properties expressed by a specialised terminology. Satellite systems originally developed for aerospace apply a different terminology. By means of a generic formalized terminology concept mutual term conversion becomes possible. Its hierarchical structure orders the specific terms of quality characteristics unambiguously up to quantities so they can be defined terminologically and determined numerically.

The quality of numerical simulations decisively depends on the used material models and their parameters. Only with good model descriptions, the behavior of components such as sensors and actuators can reliably be computed ahead. If magnetic materials are highly driven, which is necessary for an efficient use of an actuator material, hysteresis phenomena can no longer be ignored. Therefore, models are needed which can map this hysteresis phenomena, as well as correct values for the model parameters. Therefore, measurement techniques are necessary for the reliable determination of these model parameters. This paper discusses a measurement setup for magnetic vector hysteresis, the vector vibrating sample magnetometer (VVSM). The measurement setup is compared with other measurement methods. Furthermore, the parameters for a new vectorial hysteresis model are determined. The new model proposed by us is based on the classic Preisach model of hysteresis. This scalar model is extended by a rotation operator which maps a direction to each Preisach weight. The model is tested by comparing its performance to the VVSM measurements for different materials.

Vertical scanning white-light interferometers are well-established instruments for 3D-topography measurement in micro and nanotechnology. Although an axial resolution in the sub-nanometer range can be achieved, the lateral resolution is limited to the order of the wavelength of light by diffraction. Addtionally, discrepancies with respect to the correct topography appear if edge structures are measured. Here, diffraction leads to the batwing effect. An approach to analyze the transfer characteristics of optical instruments is based on the ITF (instrument transfer function), which is derived from the MTF (modulation transfer function) of imaging systems. Our results show that the ITF is not only dependent on the period of a surface profile, but also on its amplitude and shape. A rectangular profile can be measured correctly until the lateral resolution limit according to the Rayleigh criterion is reached and the surface structure is no longer optically resolved. The resolution in the case of surfaces with inhomogeneous Fresnel coefficients such as chromium structures on a glass substrate may be significantly lower. The simulation results of stochastically rough surface profiles show an overestimation if the lateral correlation length of the profile is short.

The processing of measurement data requires a detailed analysis of the measurement uncertainty. Data fusion in dimensional metrology includes transformation and estimation stages based on solving an optimization problem. The structure of the measurement uncertainty has to be considered for the analysis of these stages. The basic normative document to be applied is GUM Supplement 2. The uncertainty propagation is simulated by the Monte Carlo method. Examples with data fusion for collecting and improving data are given for the form measurement of cylindrical objects.