Showing papers on "Line segment published in 2004"

Prototype Modeling from Sketched Silhouettes based on Convolution Surfaces

Abstract: This paper presents a hybrid method for creating three-dimensional shapes by sketching silhouette curves. Given a silhouette curve, we approximate its medial axis as a set of line segments, and convolve a linearly weighted kernel along each segment. By summing the fields of all segments, an analytical convolution surface is obtained. The resulting generic shape has circular cross-section, but can be conveniently modified via sketched profile or shape parameters of a spatial transform. New components can be similarly designed by sketching on different projection planes. The convolution surface model lends itself to smooth merging between the overlapping components. Our method overcomes several limitations of previous sketched-based systems, including designing objects of arbitrary genus, objects with semi-sharp features, and the ability to easily generate variants of shapes.

Sculptured surface machining using triangular mesh slicing

Abstract: In this paper, an optimized procedure for tool path generation in regional milling is presented. The proposed procedure computes tool paths by slicing a CL-surface (Cutter Location surface), which is a triangular, mesh containing invalid triangles. Tool path generation consists of two steps: firstly, it obtains a set of line segments by slicing the triangular mesh with two-dimensional geometric elements (slicing elements), and, secondly, it extracts a valid tool path from the line segments by removing invalid portions. Two algorithms based on the slicing elements are presented: a ‘ line projection ’ algorithm based on the plane sweeping paradigm, which works efficiently by using the characteristics of a monotone chain; and a ‘ curve projection ’ algorithm for the projection of curves, which transforms the curve projection problem into a line projection problem by mapping the XYZ-space of the cylinder surface to the TZ -plane of the unfolded cylinder. The proposed procedure has been implemented and applied to tool path generation in regional milling. Performance tests show the efficiency of the proposed procedure.

Learning polyline maps from range scan data acquired with mobile robots

Abstract: Geometric representations of the environment play an important role in mobile robotics as they support various tasks such as motion control and accurate localization. Popular approaches to represent the geometric features of an environment are occupancy grids or line models. Whereas occupancy grids require a huge amount of memory and therefore do not scale well with the size of the environment, line models are unable to correctly represent corners or connections between objects. In this paper we present an algorithm that learns sets of polylines from laser range scans. Starting with an initial set of polylines generated from the range scans it iteratively optimizes these polylines using the Bayesian information criterion. During the optimization process our algorithm utilizes information about the angles between line segments extracted from the original range scans. We present experiments illustrating that our algorithm is able to learn accurate and highly compact polyline maps from laser range data obtained with mobile robots.

On-line segmentation algorithm for continuously monitored data in intensive care units

Abstract: An on-line segmentation algorithm is presented in this paper. It is developed to preprocess data describing the patient's state, sampled at high frequencies in intensive care units, with a further purpose of alarm filtering. The algorithm splits the signal monitored into line segments-continuous or discontinuous-of various lengths and determines on-line when a new segment must be calculated. The delay of detection of a new line segment depends on the importance of the change: the more important the change, the quicker the detection. The linear segments are a correct approximation of the structure of the signal. They emphasise steady-states, level changes and trends occurring on the data. The information returned by the algorithm, which is the time at which the segment begins, its ordinate and its slope, is sufficient to completely reconstruct the filtered signal. This makes the algorithm an interesting tool to provide a processed time history record of the monitored variable. It can also be used to extract on-line information on the signal, such as its trend, in the short or long term.

Robust sketched symbol fragmentation using templates

Abstract: Analysis of sketched digital ink is often aided by the division of stroke points into perceptually-salient fragments based on geometric features. Fragmentation has many applications in intelligent interfaces for digital ink capture and manipulation, as well as higher-level symbolic and structural analyses. It is our intuitive belief that the most robust fragmentations closely match a user's natural perception of the ink, thus leading to more effective recognition and useful user feedback. We present two optimal fragmentation algorithms that fragment common geometries into a basis set of line segments and elliptical arcs. The first algorithm uses an explicit template in which the order and types of bases are specified. The other only requires the number of fragments of each basis type. For the set of symbols under test, both algorithms achieved 100% fragmentation accuracy rate for symbols with line bases, ›99% accuracy for symbols with elliptical bases, and ›90% accuracy for symbols with mixed line and elliptical bases.

Algorithms for matching 3D line sets

Abstract: Matching two sets of lines is a basic tool that has applications in many computer vision problems such as scene registration, object recognition, motion estimation, and others. Line sets may be composed of infinitely long lines or finite length line segments. Depending on line lengths, three basic cases arise in matching sets of lines: 1) finite-finite, 2) finite-infinite, and 3) infinite-infinite. Case 2 has not been treated in the literature. For Cases 1 and 3, existing algorithms for matching 3D line sets are not completely satisfactory in that they either solve special situations, or give approximate solutions, or may not converge, or are not invariant with respect to coordinate system transforms. In this paper, we present new algorithms that solve exactly all three cases for the general situation. The algorithms are provably convergent and invariant to coordinate transforms. Experiments with synthetic and real 3D image data are reported.

Algorithms in digital geometry based on cellular topology

Abstract: The paper presents some algorithms in digital geometry based on the topology of cell complexes. The paper contains an axiomatic justification of the necessity of using cell complexes in digital geometry. Algorithms for solving the following problems are presented: tracing of curves and surfaces, recognition of digital straight line segments (DSS), segmentation of digital curves into longest DSS, recognition of digital plane segments, computing the curvature of digital curves, filling of interiors of n-dimensional regions (n=2,3,4), labeling of components (n=2,3), computing of skeletons (n=2, 3).

Exact reconstruction for cone-beam scanning along nonstandard spirals and other curves

Abstract: In this article we consider cone-beam CT projections along a nonstandard 3-D spiral with variable radius and variable pitch. Specifically, we generalize an exact image reconstruction formula by Zou and Pan (2004a) and (2004b) to the case of nonstandard spirals, by giving a new, analytic proof of the reconstruction formula. Our proof is independent of the shape of the spiral, as long as the object is contained in a region inside the spiral, where there is a PI line passing through any interior point. Our generalized reconstruction formula can also be applied to much more general situations, including cone-beam scanning along standard (Pack, et al. 2004) and nonstandard saddle curves, and any smooth curve from one endpoint of a line segment to the other endpoint, for image reconstruction of that line segment. In other words, our results can be regarded as a generalization of Orlov’s classical papers (1975) to cone-beam scanning.

Distance sorting algorithm for matching patterns

Abstract: The invention provides methods and systems for performing a matching function between a first pattern and a second pattern This technique involves creating a set of all distance measurements between pairs of points in the first pattern and all distance measurements between pairs of points in the second pattern This set is then partitioned into subsets of nearly equal distance elements Those subsets containing at least one element derived from each pattern determine possible line segment matches which are then analyzed mathematically to determine the partial transform that maps the associated points of the first pattern into the points of the second pattern The resulting set of partial transforms is then reviewed to determine matched line segments between the two patterns

Search continuous nearest neighbors on the air

Abstract: A continuous nearest neighbor (CNN) search retrieves the nearest neighbors corresponding to every point in a given query line segment. It is important for location-based services such as vehicular navigation tools and tourist guides. It is infeasible to answer a CNN search by issuing a traditional nearest neighbor query at every point of the line segment due to the large number of queries generated and the large overhead on bandwidth. Algorithms have been proposed recently to support CNN search in the traditional client-server service model. In this paper, we conduct a pioneering study on CNN search in wireless data broadcast environments. We propose two air indexing techniques, namely, R-tree air index and Hilbert curve air index, and develop algorithms based on these two techniques to search CNNs on the air. A simulation is conducted to compare the proposed air indexing techniques with a naive broadcast approach. The result shows that both of the proposed methods outperform the naive approach significantly. The Hilbert Curve air index is superior for uniform data distributions, while the R-tree air index is a better choice for skewed data distributions.

Curve-based representation of moving object trajectories

Abstract: In recent years, many emerging database applications deal with continuously moving data objects - each data object moves continuously and frequently reports its current location, moving direction, and speed to the database server. A database server for these applications keeps track of the trajectories of individual moving objects and processes queries referring to the past or future trajectories. Related techniques view a moving object trajectory as a sequence of connected line segments. However, most natural moving objects, such as airplanes, vessels, and vehicles, draw a smooth trajectory with no angles. This paper presents our curve-based trajectory representation models. The presented results show that the curve-based models provide much more accurate trajectories than the line-based models when we have the same amount of data (same number of reported points). In other words, the curve-based models require a smaller amount of data while providing the same accuracy in trajectory representation.

Coincidences of simplex centers and related facial structures

Abstract: We investigate the geometric properties of simplices in Euclidean d-dimensional space for which two or more of the analogues of the classical triangle centers (including the centroid, circumcenter, incenter, orthocenter or Monge point, and the Fermat-Torricelli point) coincide. We also investigate the geometric significance of the cevian line segments through a given center having the same length. We give a unified presentation, including known results for d=2 and d=3.

Fuzzy-differential evolution algorithm for planning time-optimal trajectories of a unicycle mobile robot on a predefined path

Abstract: An evolutionary technique with a Fuzzy Inference System (FIS) is offered for planning time-optimal trajectories on a predefined Visibility Graph Method Dijkstra (VGM-D) path of a Nomad 200 mobile robot (MR). First of all, the segmented trajectory is generated by the VGM-D algorithm. Line and curve segments are the components of the trajectory. The number of intersections of the segmented VGM-D path determines the curve segments number. It is assumed that, at each curve segment, translation velocity v t is taken as constant. The Differential Evolution (DE) algorithm finds v t values of all the curve segments, which minimize the trajectory tracking time. Line segments lengths are used to calculate the constraints of the problem according to the Nomad 200's limitations on the translation velocity and acceleration/deceleration. The structures of the curve segments are modeled by FIS to decrease the DE's execution time. Another FIS model is used to define the upper bound of the translation velocities on the cu...

Mram array with segmented word and bit lines

Abstract: A method and system for providing and using a magnetic random access memory (MRAM) array are disclosed. The method and system include providing magnetic storage cells (C11-C44), global word lines (102, 114) and global word line segments (170-182), of global bit lines (104, 108, 116, 120) and bit line segments (150, 164), and selection devices (T1a-T4a). Each word line segment (170) is coupled with at least one global word line (102) such that the work line segments (170-182) are selectable. Each word line segment (170) is also coupled to a portion of the magnetic storage cells (C11-C44). Each bit line segment (150) is coupled with at least one global bit line (104) such the bit line segments (150-164) are selectable. Each bit line segment (150) resides in proximity to and is used to write to a portion of the magnetic storage cells (C11-C44). The bit line segments (150-164) and the word line segments (170-182) are coupled with and selectable using the plurality of selection devices (T1a-T4a).

Triangular range counting query in 2D and its application in finding k nearest neighbors of a line segment

Abstract: We present an efficient algorithm for finding k nearest neighbors of a query line segment among a set of points distributed arbitrarily on a two dimensional plane. Along the way to finding this algorithm, we have obtained an improved triangular range searching technique in 2D. Given a set of n points, we preprocess them to create a data structure using O(n2) time and space, such that given a triangular query region Δ, the number of points inside Δ can be reported in O(logn) time. Finally, this triangular range counting technique is used for finding k nearest neighbors of a query straight line segment in O(log2 n + k) time.

Method and system for performing speculative collisions for a video game

Abstract: A system and method directed to speculating a collision in a video game. A vectorial sum of vertices of a first object, a second object, and motion vector for the first object is used to determine if a collision occurs. A shifted motion vector beginning at an origin within the vectorial sum, with substantially same orientation as the motion vector is employed to determine an intersection on a collision plane. A first triangle is constructed containing the origin and having vertices among vertices of the vectorial sum. Subsequent triangles sharing one edge with a previous triangle are constructed without overlapping. The iterative construction process is terminated when no vertex of the vectorial sum remains to be selected for a new triangle. A time and location of the collision is determined based on coordinates of the triangle vertices establishing a length of a line segment between the origin and the intersection.

Piecewise polygonal approximation of digital curves

Abstract: In this paper, we present a recursive algorithm for piecewise polygonal approximation of a digital curves. The idea behind is to look for an optimal solution while approximating the given curve segment with a set of longest and minimum line segments such that the maximum squared error is less than the given threshold. The given curve is divided into pieces and parallel processing can be applied to each piece of curve thus making it computationally more efficient. Experimental results show that the proposed method has promising results.

Face recognition using interpolated Bezier curve based representation

Abstract: This paper proposes an efficient face recognition scheme, which incorporates certain methods. In this scheme, edges are obtained from sobelled face images. The major feature areas are segmented and principal curves are obtained by applying thinning algorithm on the features of resulting face image. A modified thinning algorithm based on line sweep procedures is used. A line sweep is a process where the plane is divided into parallel slabs by lines passing through certain "events" and then items are processed according to an order of the slabs [A Line Sweep thinning Algorithm]. A new method for Bezier contour point interpolation is used after locating the two end points of the curve on the prime facial features. The two control points of a Bezier curve are interpolated by this method. The Bezier points i.e. the two end points of a curve and the two control points, form the line segments whose Hausdroff distances are calculated as specified in the algorithm discussed in this paper. The recognition rate is 100% on normal faces and also on faces with some simple expressions.

A general framework for error analysis in measurement-based GIS Part 3: Error analysis in intersections and overlays

Abstract: This is the third of a four-part series on the development of a general framework for error analysis in measurement-based geographic information systems (MBGIS). In this paper, we study the characteristics of error structures in intersections and polygon overlays. When locations of the endpoints of two line segments are in error, we analyze errors of the intersection point and obtain its error covariance matrix through the propagation of the error covariance matrices of the endpoints. An approximate law of error propagation for the intersection point is formulated within the MBGIS framework. From simulation experiments, it appears that both the relative positioning of two line segments and the error characteristics of the endpoints can affect the error characteristics of the intersection. Nevertheless, the approximate law of error propagation captures nicely the error characteristics under various situations. Based on the derived results, error analysis in polygon-on-polygon overlay operation is also performed. The relationship between the error covariance matrices of the original polygons and the overlaid polygons is approximately established.

Graphics identification program

Abstract: An information processing device executing a graphics identification program detects a trace drawn on an input surface as coordinate points in chronological order. Coordinate points for representing the trace are selected from a group of coordinate points arranged in chronological order. Lengths of line segments obtained by connecting the selected coordinate points in chronological order are calculated. Also, for each line segment, an absolute angle and a relative angle are calculated. A trace graph in an orthogonal coordinate system, whose first axis indicates a line segment distance and whose second axis indicates an angle of a line segment whose start point is one of the selected coordinate points, is compared with a reference graphic graph representing a reference graphic in the orthogonal coordinate system, thereby identifying a reference graphic represented by a reference graphic graph which most closely resembles the trace graph as a shape of the trace.

High-Speed Feature Extraction in Sensor Coordinates for Laser Rangefinders

Abstract: The main contributions of this paper are two algorithms for extracting lines and corners present in the environment from information gathered by a laser rangefinder. The laser range scan is processed in its natural coordinates, range and bearing, to compute a parameter that is invariant to the position and orientation of straight lines present. An algorithm to extract the slopes of these lines is also presented. LogHough transform, that only explores a small region of the Hough space identified by the slopes computed, is then used to find the equations of the lines. An additional computation is used to identify consecutive short line segments that are perpendicular to each other in order to extract the corners present. The proposed method carries out all computations in the sensor coordinate frame yielding a fast and robust algorithm for feature extraction from laser range scans. Practical examples are presented to demonstrate the efficacy of the algorithm. An implementation of the simultaneous localisation and mapping that does not use any odometry is also provided to illustrate the use of the features extracted by the algorithm in robot navigation.

Device and method for phase shifting

Abstract: A device and a method for phase shifting on at least one single-layer or multilayer substrate, in particular a substrate also having at least one metallic layer, to which is applied at least one planar line, in particular in the form of a strip line or in the form of a symmetrical or asymmetrical coplanar line or in the form of a microstrip line or in the form of a slot line or in the form of a coplanar dual-strip line so that the advantages of a slow-wave structure may also be used in mechanically controllable phase shifters, the phase shift is adjustable by varying the effective dielectric constant, in particular the propagation coefficient, of the line by providing line sections going out from the line, in particular no-load line sections and/or in particular line sections short-circuited at their particular ends and/or stubs going out from the line and/or alternating line segments of a high impedance and line segments of a low impedance and/or discrete elements such as inductors, capacitors or inductive and/or capacitive line bridges and/or in particular discrete serial and/or parallel reactances and/or in particular discrete serial and/or parallel susceptances and/or in particular effective line quantities per unit length such as capacitance per unit length, e.g., transverse capacitance per unit length, or inductance per unit length, e.g., longitudinal inductance per unit length.

Method and device for smoothing a melody line segment

Abstract: A tone smoothing is performed such that to each time section of a melody line segment a number is associated such that for all groups of directly neighboring time sections, to which the same spectral component is associated by the melody line segment, the numbers associated with the directly neighboring time sections are different numbers from one to the number of the directly neighboring time sections, for each spectral component that is associated with one of the time sections of the melody line segment, the numbers of those groups are added up to which time sections of the same the respective spectral component is associated by the melody line segment, a smoothing spectral component is determined as the spectral component for which the greatest summing-up results, and the melody line segment is changed, by associating the determined smoothing spectral component to each time section of the melody line segment. By this, in particular the inadequacy of monophonic audio signals is considered, usually comprising a transient process at beginnings of notes, so that only to the end of the notes the desired note pitch is achieved.

Partial shape matching of spine X-ray shapes using dynamic programming

Abstract: The osteophyte shows only on some particular locations on the vertebra. This indicates that other locations on the vertebra shape contain that are not of interest hinder the spine X-ray image retrieval relevance precision, which motivates our research in partial shape matching (PSM). This paper presents PSM methods for matching shapes with variable number of points and with different data point distributions. Dynamic programming (DP) is proposed for matching partial shapes by allowing merging of the data points in the process of PSM. DP is implemented based on two shape representation methods: line segments and multiple open triangles. The performance evaluation, which is based on human relevance judgements of these two shape representations in PSM is also presented.

Method and apparatus of adaptive de-interlacing of dynamic image

Abstract: The present invention provides a method and apparatus of adaptive de-interlacing of dynamic image, configured for calculating characteristic values of each line segment of current frame in sequence according to width of line segment. Next, calculating the difference between characteristic values of each line segment of current frame and characteristic values of each corresponding line segment of reference frame in sequence to acquire an image shift value of line segment. And next, comparing the image shift value of line segment with a threshold to determine a de-interlacing algorithm for executing the de-interlacing and constituting a high-resolution dynamic image. At the same time, storing characteristic values of each line segment of current frame for being the characteristic values of each corresponding line segment of the former frame when calculating the image shift value of line segment of the next frame. By adjusting width of line segment and a threshold, it can control which kind of de-interlacing for using and information amount of each de-interlacing process to acquire good image quality of dynamic image and elasticity of operation.

Parallelotopes of non-zero width

Abstract: In 1959, Venkov introduced a concept of polytope of non-zero width in the direction of a subspace and studied parallelotopes of non-zero width. In the present paper properties of a parallelotope of non-zero width in the direction of a straight line are investigated. In particular, it is proved that a parallelotope of non-zero width in the direction of a straight line is the Minkowski sum of a parallelotope of width zero and a segment of this line. Necessary and sufficient conditions ensuring that the sum of a parallelotope and a line segment is again a parallelotope are presented.

System and method for processing imagery using optical flow histograms

Abstract: A method, computer program product, and system for processing imagery is presented. The imagery is processed by receiving data regarding a scene (such as from a sensor monitoring a scene). The scene includes an object having a dimension. Flow vectors are computed from the data, while a flow histogram space is generated from the flow vectors. A line segment (with a length) is found within the flow histogram space. An object in the scene is associated with the length segment, and the dimensions of the object are estimated based on the length of the line segment.

Method and apparatus for determining a transmit PSD at a remote location

Abstract: The present invention relates to a method for determining a transmit PSD over a remotely-deployed line, which method comprising the steps of: modeling a first far-end crosstalk originating from the line and coupling into a centrally-deployed victim neighboring line, modeling a second far-end crosstalk originating from a further centrally-deployed neighboring line and coupling into the victim neighboring line, determining the transmit PSD from the first modeled far-end crosstalk and the second modeled far-end crosstalk. A method according to the invention further comprises the steps of: expressing the transmit PSD as a function of a line parameter characterizing a line segment of the further neighboring line, carrying out channel measurements of a spare line that connects the central location to the remote location, and that shares common transmission characteristics with the line segment, estimating from said channel measurements a value of the line parameter, determining therefrom the transmit PSD. The present invention also relates to a power control unit.

Qualitative Spatial Reasoning about Oriented Points

Abstract: We present a qualitative positional calculus which uses oriented points as basicentities. In contrast to often-used simple points, we consider objects that havean intrinsic direction. Having an intrinsic orientation is an important property ofnatural objects. 1 Introduction Qualitative Reasoning about space abstracts from the physical world and enables com-puters to make predictions about spatial relations, even when a precise quantitativeinformation is not available [2]. The two main trends in Qualitative Spatial Reason-ing are topological reasoning about regions [2, 9] and positional reasoning about pointcongurations [3, 11]. Especially positionalreasoningis importantfor robotnavigation[8].Back FrontLeftRight Figure 1: An oriented point and its qualitative spatial relative directionsIn the aforementioned approaches about orientations objects and locations are rep-resentedas simple, featureless points. In contrast, ourpaperpresents a positionalcalcu-lus whichuses morecomplexbasic entities. It is basedonobjects whicharerepresentedas oriented points. It is closely related to a previously designed calulus which is basedon straight line segments (dipoles) [7]. Conceptually our new calculus can be viewedas a transition from oriented line segements with concrete lenght to line segments with1

Method and apparatus for identifying a graphic shape

Abstract: An information processing device executing a graphics identification program detects a trace drawn on an input surface as coordinate points in chronological order. Coordinate points for representing the trace are selected from a group of coordinate points arranged in chronological order. Lengths of line segments obtained by connecting the selected coordinate points in chronological order are calculated. Also, for each line segment, an absolute angle and a relative angle are calculated. A trace graph in an orthogonal coordinate system, whose first axis indicates a line segment distance and whose second axis indicates an angle of a line segment whose startpoint is one of the selected coordinate points, is compared with a reference graphic graph representing a reference graphic in the orthogonal coordinate system, thereby identifying a reference graphic represented by a reference graphic graph which most closely resembles the trace graph as a shape of the trace.