1,929,665 research outputs found
A Fisher-Rao metric for paracatadioptric images of lines
No full textIn a central paracatadioptric imaging system a perspective camera takes an image of a scene reflected in a paraboloidal mirror. A 360° field of view is obtained, but
the image is severely distorted. In particular, straight lines in the scene project to circles in the image. These distortions make it diffcult to detect projected lines using standard image processing algorithms. The distortions are removed using a Fisher-Rao metric which is defined on the space of projected lines in the paracatadioptric image. The space of projected lines is divided into subsets such that on each subset the Fisher-Rao metric is closely approximated by the Euclidean metric. Each subset is sampled at the vertices of a square grid and values are assigned to the sampled points using an adaptation of the trace transform. The result is a set of digital images to which standard image processing algorithms can be applied.
The effectiveness of this approach to line detection is illustrated using two algorithms, both of which are based on the Sobel edge operator. The task of line detection is reduced to the task of finding isolated peaks in a Sobel image. An experimental comparison is made between these two algorithms and third algorithm taken from the literature and
based on the Hough transform
Application of the Fisher-Rao metric to ellipse detection
No full textThe parameter space for the ellipses in a two dimensional image is a five dimensional manifold, where each point of the manifold corresponds to an ellipse in the image. The parameter space becomes a Riemannian manifold under a Fisher-Rao metric, which is derived from a Gaussian model for the blurring of ellipses in the image. Two points in the parameter space are close together under the Fisher-Rao metric if the corresponding ellipses are close together in the image. The Fisher-Rao metric is accurately approximated by a simpler metric under the assumption that the blurring is small compared with the sizes of the ellipses under consideration. It is shown that the parameter space for the ellipses in the image has a finite volume under the approximation to the Fisher-Rao metric. As a consequence the parameter space can be replaced, for the purpose of ellipse detection, by a finite set of points sampled from it. An efficient algorithm for sampling the parameter space is described. The algorithm uses the fact that the approximating metric is flat, and therefore locally Euclidean, on each three dimensional family of ellipses with a fixed orientation and a fixed eccentricity. Once the sample points have been obtained, ellipses are detected in a given image by checking each sample point in turn to see if the corresponding ellipse is supported by the nearby image pixel values. The resulting algorithm for ellipse detection is implemented. A multiresolution version of the algorithm is also implemented. The experimental results suggest that ellipses can be reliably detected in a given low resolution image and that the number of false detections
can be reduced using the multiresolution algorithm
Narayanella, a new name for Narayana Subba Rao (hymenoptera : mymaridae)
No full textThe name Narayana was applied (Subba Rao, 1976) to a genus erected for the new species N. pilipes reared from the gaUs of Lagerstoemia flos reginae. Unfortunately the author overlooked the vulid and prior use of Narayana by Distant (1908). Narayana Distant was erected with rusticitatus as type-species (Issidae: Homoptera). Hence Narayana Subba Rao is a junior homonym which has to be replaced according to the rules of the International Zoological Nomenclature
Cramér-Rao Bound for Hybrid GNSS-Terrestrial Cooperative Positioning
Get PDFIn this contribution we derive an expression of the Cramer-Rao bound for hybrid cooperative positioning, where GNSS information is combined with terrestrial range measurements through exchange of peer-to-peer messages. These results provide a theoretical characterization of achievable performance of hybrid positioning schemes, as well as allow to identify critical network configurations and devise optimized node placement strategies
Mapping the Imagination: Literary Geography, Special issue of Literary Geographies.
No full textEleonora Rao is the Guest Editor of the special issue, "Mapping the Imagination: Literary Geography
Empirical likelihood inference for the Rao-Hartley-Cochran sampling design
No full textThe Hartley-Rao-Cochran sampling design is an unequal probability sampling design which can be used to select samples from finite populations. We propose to adjust the empirical likelihood approach for the Hartley-Rao-Cochran sampling design. The approach proposed intrinsically incorporates sampling weights, auxiliary information and allows for large sampling fractions. It can be used to construct confidence intervals. In a simulation study, we show that the coverage may be better for the empirical likelihood confidence interval than for standard confidence intervals based on variance estimates. The approach proposed is simple to implement and less computer intensive than bootstrap. The confidence interval proposed does not rely on re-sampling, linearization, variance estimation, design-effects or joint inclusion probabilities
Sensor Selection for Angle of Arrival Estimation Based on the Two-Target Cramér-Rao Bound
No full textSensor selection is a useful method to help reduce data throughput, as well as computational, power, and hardware requirements, while still maintaining acceptable performance. Although minimizing the Cramér-Rao bound has been adopted previously for sparse sensing, it did not consider multiple targets and unknown source models. In this work, we propose to tackle the sensor selection problem for angle of arrival estimation using the worst-case Cramér-Rao bound of two uncorrelated sources. To do so, we cast the problem as a convex semi-definite program and retrieve the binary selection by randomized rounding. Through numerical examples related to a linear array, we illustrate the proposed method and show that it leads to the natural selection of elements at the edges plus the center of the linear array. This contrasts with the typical solutions obtained from minimizing the single-target Cramér-Rao bound.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Signal Processing System
Economic philosophy of V.K.R.V. Rao
Get PDFProf. V.K.R.V. Rao falls in the line of great Indian leaders and scholars such as M.G. Ranade, Gandhiji, J.K. Mehta, who emphasised the human values and ethics in the discipline of economics. For him the nature and purpose of economic activity is different from what is prescribed in the conventional economics. By conventional economics we mean the mainstream economics inherited from the West. The present paper attempts to examine the economic philosophy of Rao in the light of his numerous works and the criticism leveled by him against the conventional economics.V.K.R.V. Rao; Indian Economic Thought; Ethics and economics; cooperation; the myth of consumers' sovereignty;Human factor in economic development.
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