CIRCULAR ARC SEGMENTATION BY CURVATURE ESTIMATION AND GEOMETRIC VALIDATION

2012 ◽  
Vol 12 (04) ◽  
pp. 1250024 ◽  
Author(s):  
SHYAMOSREE PAL ◽  
RAHUL DUTTA ◽  
PARTHA BHOWMICK
Keyword(s):  
Geometric Analysis ◽  
Circular Arc ◽  
Discrete Curvature ◽  
Circular Arcs ◽  
Initial Stage ◽  
Benchmark Datasets ◽  
Curvature Estimation ◽  
Digital Curve ◽  
Curvature Information ◽  
Novel Algorithm

A novel algorithm to detect circular arcs from a digital image is proposed. The algorithm is based on discrete curvature estimated for the constituent points of digital curve segments, followed by a fast geometric analysis. The curvature information is used in the initial stage to find the potentially circular segments. In the final stage, the circular arcs are merged and maximized in length using the radius and center information of the potentially circular segments. Triplets of longer segments are given higher priorities; doublets and singleton arcs are processed at the end. Detailed experimental results on benchmark datasets demonstrate its efficiency and robustness.

Research of Discrete Curvature Estimation Method Based on Local Space Parabola

2014 ◽  
Vol 577 ◽  
pp. 802-805 ◽  
Author(s):  
Jian Wei Ma ◽  
Zhen Yuan Jia ◽  
Fu Ji Wang
Keyword(s):  
Point Cloud ◽  
Simulation Experiment ◽  
Estimation Method ◽  
Circular Arc ◽  
Discrete Curvature ◽  
Fitting Method ◽  
Local Space ◽  
Scan Line ◽  
Curvature Estimation ◽  
Line Point

Curvature estimation of 3-dimension discrete points performs an important role in dealing with scan line point cloud and is difficult to calculate. A discrete curvature estimation method based on local space parabola is proposed. Method in this paper is contrasted with circular arc fitting method and simulation experiment shows that the proposed method is feasible and effective with high precision.

Circular-Arc Radial Cams with One Connection Arc

2020 ◽  
Vol 896 ◽  
pp. 83-94
Author(s):  
Simona Mariana Cretu ◽  
Ionuţ Daniel Geonea
Keyword(s):  
Line Profile ◽  
Kinematic Analysis ◽  
Geometric Analysis ◽  
Circular Arc ◽  
Circular Arcs ◽  
Straight Line ◽  
Cam Profile

This paper deals with the geometric and kinematic analysis of the circular-arc profile cams with one connection arc. If the maximum lift of the follower is required, it is shown that it is possible to connect two circular-arcs – that are defined by center of curvature and radius – through a single circular-arc, and the connection points result. But, if the connection points of two given circular-arcs of the cam profile are required, at least two circular-arcs are needed to connect them. The specific equations for the geometric analysis for one circular-arc profile are described. Also, for two mechanisms, one with straight-line profile and another with one circular-arc connection profile, the geometric and kinematic analysis and simulations of the movements using SolidWorks and ADAMS programs are presented

Design constraints of five-arc Roots vacuum pumps

2002 ◽  
Vol 216 (2) ◽  
pp. 225-234 ◽  
Author(s):  
P-Y Wang ◽  
Z-H Fong ◽  
H S Fang
Keyword(s):  
Design Procedure ◽  
Vacuum Pump ◽  
Tooth Profile ◽  
Design Constraints ◽  
Circular Arc ◽  
Ultimate Pressure ◽  
Rotor Profile ◽  
Circular Arcs ◽  
Centre Of Rotation ◽  
Inlet Opening

The design constraints for the tooth profile of the five-arc Roots vacuum pump are derived and discussed in this paper. The addendum portion of the five-arc tooth profile comprises five smoothly connected circular arcs, while the dedendum portion consists of conjugate curves of the addendum portion of the mating rotor. The top land of the proposed rotor profile is a circular arc with its centre coinciding with the centre of rotation. Therefore, the gap between the top land of the rotor and the wall of the chamber turns into a long and narrow path, which provides better gas sealing and wider inlet opening. The design constraints of the rotor profile are quite complex owing to the limitations of zero carryover and the condition of non-undercutting. A design procedure is proposed for determining the feasible design region by considering the geometry constraints, zero carryover and non-undercutting. By using the proposed procedure, wider inlet opening and better gas sealing are expected, while the characteristic of zero carryover is maintained. The results of experiment show that the ultimate pressure of the prototype of the five-arc Roots vacuum pump is 2,5 × 10-3 torr, and the maximum pumping speed is 1600L/min. The performance of the prototype is excellent compared with commercially available mechanical dry vacuum pumps.

scholarly journals A High-Robust Automatic Reading Algorithm of Pointer Meters Based on Text Detection

Sensors ◽  
2020 ◽  
Vol 20 (20) ◽  
pp. 5946
Author(s):  
Zhu Li ◽  
Yisha Zhou ◽  
Qinghua Sheng ◽  
Kunjian Chen ◽  
Jian Huang
Keyword(s):  
Adaptive Detection ◽  
Test Results ◽  
Linear Scale ◽  
Distance Method ◽  
Circular Arc ◽  
Scale Line ◽  
Different Types ◽  
Efficient Measurement ◽  
Automatic Reading ◽  
Novel Algorithm

Automatic reading of pointer meters is of great significance for efficient measurement of industrial meters. However, existing algorithms are defective in the accuracy and robustness to illumination shooting angle when detecting various pointer meters. Hence, a novel algorithm for adaptive detection of different pointer meters was presented. Above all, deep learning was introduced to detect and recognize scale value text in the meter dial. Then, the image was rectified and meter center was determined based on text coordinate. Next, the circular arc scale region was transformed into a linear scale region by polar transform, and the horizontal positions of pointer and scale line were obtained based on secondary search in the expanded graph. Finally, the distance method was used to read the scale region where the pointer is located. Test results showed that the algorithm proposed in this paper has higher accuracy and robustness in detecting different types of meters.

scholarly journals A Discrete Curvature Estimation Based Low-Distortion Adaptive Savitzky–Golay Filter for ECG Denoising

Sensors ◽  
2019 ◽  
Vol 19 (7) ◽  
pp. 1617 ◽  
Author(s):  
Hui Huang ◽  
Shiyan Hu ◽  
Ye Sun
Keyword(s):  
Consumer Electronics ◽  
High Signal ◽  
Wearable Electronics ◽  
Signal Distortion ◽  
Data Smoothing ◽  
Discrete Curvature ◽  
Ecg Denoising ◽  
Curvature Estimation ◽  
Low Distortion ◽  
Distortion Reduction

Electrocardiogram (ECG) sensing is an important application for the diagnosis of cardiovascular diseases. Recently, driven by the emerging technology of wearable electronics, massive wearable ECG sensors are developed, which however brings additional sources of noise contamination on ECG signals from these wearable ECG sensors. In this paper, we propose a new low-distortion adaptive Savitzky-Golay (LDASG) filtering method for ECG denoising based on discrete curvature estimation, which demonstrates better performance than the state of the art of ECG denoising. The standard Savitzky-Golay (SG) filter has a remarkable performance of data smoothing. However, it lacks adaptability to signal variations and thus often induces signal distortion for high-variation signals such as ECG. In our method, the discrete curvature estimation is adapted to represent the signal variation for the purpose of mitigating signal distortion. By adaptively designing the proper SG filter according to the discrete curvature for each data sample, the proposed method still retains the intrinsic advantage of SG filters of excellent data smoothing and further tackles the challenge of denoising high signal variations with low signal distortion. In our experiment, we compared our method with the EMD-wavelet based method and the non-local means (NLM) denoising method in the performance of both noise elimination and signal distortion reduction. Particularly, for the signal distortion reduction, our method decreases in MSE by 33.33% when compared to EMD-wavelet and by 50% when compared to NLM, and decreases in PRD by 18.25% when compared to EMD-wavelet and by 25.24% when compared to NLM. Our method shows high potential and feasibility in wide applications of ECG denoising for both clinical use and consumer electronics.

Mitered Offsets and Skeletons for Circular Arc Polygons

2020 ◽  
Vol 30 (03n04) ◽  
pp. 235-256
Author(s):  
Bastian Weiß ◽  
Bert Jüttler ◽  
Franz Aurenhammer
Keyword(s):  
Monotonicity Property ◽  
Free Form ◽  
Shape Preserving ◽  
Circular Arc ◽  
Spline Curves ◽  
Circular Arcs ◽  
Event Driven ◽  
Planar Shapes ◽  
Practical Performance

The offsetting process that defines straight skeletons of polygons is generalized to arc polygons, i.e., to planar shapes with piecewise circular boundaries. The offsets are obtained by shrinking or expanding the circular arcs on the boundary in a co-circular manner, and tracing the paths of their endpoints. These paths define the associated shape-preserving skeleton, which decomposes the input object into patches. While the skeleton forms a forest of trees, the patches of the decomposition have a radial monotonicity property. Analyzing the events that occur during the offsetting process is non-trivial; the boundary of the offsetting object may get into self-contact and may even splice. This leads us to an event-driven algorithm for offset and skeleton computation. Several examples (both manually created ones and approximations of planar free-form shapes by arc spline curves) are analyzed to study the practical performance of our algorithm.

Error Estimate of Approximate Double Circular Arc Interpolated Method for Curve Smoothing

2004 ◽  
Vol 471-472 ◽  
pp. 92-95 ◽  
Author(s):  
Zi Qiang Zhang ◽  
Qiu Sheng Yan ◽  
Zhi Dan Zheng ◽  
Shao Bo Chen
Keyword(s):  
Error Estimate ◽  
Reverse Engineering ◽  
Nc Machining ◽  
Intersection Point ◽  
Circular Arc ◽  
Original Curve ◽  
Circular Arcs ◽  
Curve Smoothing ◽  
Estimate Error

Approximate Double Circular Arc Interpolated Method which was put forward by author, is different from other circular arc interpolated methods in demanding only the corner between normal directions of each circular arcs at intersection point are less than designated allowed value but not demanding contiguous circular arcs are tangent, and makes the calculating be predigested. In order to estimate error of the method, emulated calculating is carried out, namely the course of curve being obtained by reverse engineering is simulated in this paper. The results show: if space between measure points is about 0.1mm in curve being obtained by reverse engineering, then, the most departure of smoothing results from original curve is 0.552μm for the stated example. Influence of the error on NC machining is quite small, so it can meet the needs of NC machining.

Finding a Maximum Clique in a Set of Proper Circular Arcs in Time O(n) with Applications

1997 ◽  
Vol 08 (04) ◽  
pp. 443-467 ◽  
Author(s):  
Glenn K. Manacher ◽  
Terrance A. Mankus
Keyword(s):  
Time Complexity ◽  
Maximum Clique ◽  
Special Property ◽  
Maximum Weight ◽  
Time And Space ◽  
Circular Arc ◽  
Interval Model ◽  
Circular Arcs ◽  
The One ◽  
Circular Arc Graphs

A maximum clique is sought in a set of n proper circular arcs (PCAS). By means of several passes, each O(n) in time and space, a PCAS is transformed initially into a set of circle chords and finally into a set of intervals. This interval model inherits a special property from the PCAS which ensures the discovery of a maximum overlap clique in time O(n). The one-to-one arc/interval correspondence guarantees the identification of the maximum clique in the PCAS in O(n) time and space. The present paper gives new, simpler proofs for the lemmas first outlined by us in Ref. [9], extending the methods outlined in that paper so that the time bound is improved from O(n log n) to O(n). The method depends only on certain interconnections between constructions related to the computation of longest increasing subsequences. Independently, Hell, Huang and Bhattacharya5 recently discovered a completely different approach that also achieves the same complexity, and can moreover be applied to the weighted case and to the coloring problem on proper circular arcs. The previous best result, due to Apostolico and Hambrusch2 applies to general circular arc models and has time complexity O(n2 log log n) and space complexity O(n). As applications of the method, we show that maximum weight clique of a set of weighted proper circular arcs can be found in time O(n2) and space O(n). The previous best result was O(n2 log log n) for dense general circular arc graphs.13 We also show that, for n chords with randomly placed endpoints (1) the average cardinality of a maximum clique is cn1/2 ± o(n1/2), where 21/2< c < e21/2, and (2) a maximum clique may be found in average time O(n3/2) and space θ(n). The previous best average time complexity, derived from Ref. [1], was O(n3/2 log n).

scholarly journals Hardware Acceleration of Sparse Oblique Decision Trees for Edge Computing

2019 ◽  
Vol 25 (5) ◽  
pp. 18-24
Author(s):  
Predrag Teodorovic ◽  
Rastislav Struharik
Keyword(s):  
Machine Learning ◽  
Decision Trees ◽  
Hardware Acceleration ◽  
Hardware Accelerator ◽  
Significant Interest ◽  
Benchmark Datasets ◽  
Edge Based ◽  
Specialized Hardware ◽  
Memory Resources ◽  
Novel Algorithm

This paper presents a hardware accelerator for sparse decision trees intended for FPGA applications. To the best of authors’ knowledge, this is the first accelerator of this type. Beside the hardware accelerator itself, a novel algorithm for induction of sparse decision trees is also presented. Sparse decision trees can be attractive because they require less memory resources and can be more efficiently processed using specialized hardware compared to traditional oblique decision trees. This can be of significant interest, particularly, in the edge-based applications, where memory and compute resources as well as power consumption are severely constrained. The performance of the proposed sparse decision tree induction algorithm as well as developed hardware accelerator are studied using standard benchmark datasets obtained from the UCI Machine Learning Repository database. The results of the experimental study indicate that the proposed algorithm and hardware accelerator are very favourably compared with some of the existing solutions.

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