We propose an approach to accurately detecting two dimensional shapes. The cross-section of the shape boundary is modeled as a step function. We first derive a one-dimensional optimal step edge operator, which minimizes both the noise power and the mean squared error between the input and the filter output. This operator is found to be the derivative of the double exponential (DODE) function. W...

Grip kinetics and their variation are emerging as important considerations in the clinical assessment of handwriting pathologies, fine motor rehabilitation, biometrics, forensics and ergonomic pen design. This study evaluated the intra- and inter-participant variability of grip shape kinetics in adults during signature writing. Twenty (20) adult participants wrote on a digitizing tablet using a...

The main method to control bit errors is to use a combination of forward error correction (FEC) and link-layer retransmissions (ARQ, which stands for “automatic repeat request”). In addition, modern wireless devices can transmit at multiple different rates using different modulation schemes, adapting their transmission rate to prevailing channel conditions. Such schemes are often called autorat...

In this paper three p-adaptation strategies based on the minimization of the truncation error are presented for high order discontinuous Galerkin methods. The truncation error is approximated by means of a r-estimation procedure and enables the identification of mesh regions that require adaptation. Three adaptation strategies are developed and termed a posteriori, quasi-a priori and quasi-a pr...

Folding of RNA sequences into secondary structures is viewed as a map that assigns a uniquely defined base pairing pattern to every sequence. The mapping is non-invertible since many sequences fold into the same minimum free energy (secondary) structure or shape. The pre-images of this map, called neutral networks, are uniquely associated with the shapes and vice versa. Random graph theory is u...

Studies of DEM error have consistently found a link between terrain characteristics such as slope shape or steepness and error. This link is explored by looking at error in relation to various geomorphometric measures for a study area in Scotland. The magnitude of error is found to vary systematically between convex, planar and convex areas and measures of terrain roughness show some degree of ...

This article studies the problem of approximating functions belonging to a Hilbert space Hd with an isotropic or anisotropic Gaussian reproducing kernel, Kd(x, t) = exp ( − d ∑ l=1 γ l (xl − tl)2 ) for all x, t ∈ R. The isotropic case corresponds to using the same shape parameters for all coordinates, namely γl = γ > 0 for all l, whereas the anisotropic case corresponds to varying shape paramet...

Statistical shape analysis techniques employed in the medical imaging community, such as Active Shape Models or Active Appearance Models, rely on Principal Component Analysis (PCA) to decompose shape variability into a reduced set of interpretable components. Our model uses point distribution models (PDM) for the representation of shapes. The point association is initialized using shape-based s...

The paper presents an analysis of a nonlinear filtering problem corresponding to tracking of an extended target whose shape is modelled by an ellipse. The measurements of target extent are assumed to be available in addition to the usual positional measurements. Using Cramer-Rao bounds we establish the best achievable error performance for this highly nonlinear problem. The theoretical bounds a...

Due to small training sets, statistical shape models constrain often too much the deformation in medical image segmentation. Hence, an artificial enlargement of the training set has been proposed as a solution for the problem. In this paper, the error sources in the statistical shape model based segmentation were analyzed and the optimization processes were improved. The method was evaluated wi...