Internal and external algorithms for the points-in-regions problem—the inside join of geo-relational algebra

We consider the problem of collectively locating a set of points within a set of disjoint polygonal regions when neither for points nor for regions preprocessing is allowed. This problem arises in geometric database systems. More specifically it is equivalent to computing theinside join of geo-relational algebra, a conceptual model for geo-data management. We describe efficient algorithms for solving this problem based on plane-sweep and divide-and-conquer, requiringO(n(logn) +t) andO(n(log² n) +t) time, respectively, andO(n) space, wheren is the total number of points and edges, and (is the number of reported (point, region) pairs. Since the algorithms are meant to be practically useful we consider as well as the internal versions-running completely in main memory-versions that run internally but use much less than linear space and versions that run externally, that is, require only a constant amount of internal memory regardless of the amount of data to be processed. Comparing plane-sweep and divide-and-conquer, it turns out that divide-and-conquer can be expected to perform much better in the external case even though it has a higher internal asymptotic worst-case complexity. An interesting theoretical by-product is a new general technique for handling arbitrarily large sets of objects clustered on a singlex-coordinate within a planar divide-and-conquer algorithm and a proof that the resulting “unbalanced” dividing does not lead to a more than logarithmic height of the tree of recursive calls.     

On thermal and vibrational properties of LaGaO3 single crystals

The thermal expansion and vibrational properties of [1 0 0] and [0 0 1] LaGaO₃ single crystals have been studied by thermal mechanical analysis and micro-Raman spectroscopy. A first-order orthorhombic to rhombohedral phase transition has been confirmed by both techniques, as well as by in situ heating using optical microscopy. The appearance of a metastable intermediate phase, tentatively assigned as monoclinic, has been detected both by optical microscopy and Raman spectroscopy upon heating of the [1 0 0] and [0 0 1] LaGaO₃ single crystals. Not only temperature, but the stress-induced orthorhombic to rhombohedral phase transition has also been detected by Raman mapping of the residual impression made by Vickers indentation. The position map of bands belonging to the lower-temperature/pressure orthorhombic and the higher-temperature/pressure rhombohedral phase show that the rhombohedral phase is located inside the impression, where the applied indentation stresses are the highest, whereas no rhombohedral phase is detected outside the impression, where the surface has not been altered by contact stresses.     

Segmenting images using localized histograms and region merging

A working system for segmenting images of complex scenes is presented. The system integrates techniques that have evolved out of many years of research in low-level image segmentation at the University of Massachusetts and elsewhere. This paper documents the result of this historical evolution. Segmentations produced by the system are used extensively in related image interpretation research.The system first produces segmentations based upon an analysis of spatially localized feature histograms. These initial segmentations are then simplified using a region merging algorithm. Parameter selection for the local histogram segmentation algorithm is facilitated by mapping the multidimensional parameter space to a one-dimensional parameter which regulates region fragmentation. An extension of this algorithm to multiple features is also presented. Experience with roughly 100 images from different domains has shown the system to be robust and effective. Samples of these results are included.     

Bin-picking with a solid state range camera

In this paper we present new work done on the bin-picking problem. The work was triggered by the advent of a new solid state range camera which enables the economic and robust use of range imagery in industrial robotic automation tasks. The application presented is that of pick-and-place of randomly oriented but known polyhedral objects in an industrial robotic work cell. The algorithms for segmentation, pose estimation, and grasp point determination are presented along with practical results from a real industrial grade work cell.     

VC Management for Heterogeneous QoS Multicast Transmissions

A crucial component of the interaction between ATM's and the Internet's Quality of Service (QoS) architectures is the efficient mapping of RSVP (Resource reSerVation Protocol) as the Internet's signalling protocol onto the according ATM mechanisms. In particular, this article focuses on one of the most contrary characteristics of RSVP and ATM signalling. This is the support for heterogeneous reservations by RSVP over the ATM subnetwork, taking into account that ATM only allows for a homogeneous QoS within a single Virtual Circuit (VC). We present previous approaches to the solution of this problem and argue for more sophisticated and efficient approaches to manage ATM VCs taking into consideration ATM tariffs and resource consumption.