scholarly journals A Fast and Robust Ellipse-Detection Method Based on Sorted Merging

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
Gangyi Wang ◽  
Guanghui Ren ◽  
Zhilu Wu ◽  
Yaqin Zhao ◽  
Lihui Jiang
Keyword(s):  
Detection Method ◽  
Semimajor Axis ◽  
High Accuracy ◽  
Ellipse Fitting ◽  
Line Segments ◽  
Ellipse Detection ◽  
Fitting Method ◽  
Merging Process ◽  
Real Time Applications ◽  
Merging Strategy

A fast and robust ellipse-detection method based on sorted merging is proposed in this paper. This method first represents the edge bitmap approximately with a set of line segments and then gradually merges the line segments into elliptical arcs and ellipses. To achieve high accuracy, a sorted merging strategy is proposed: the merging degrees of line segments/elliptical arcs are estimated, and line segments/elliptical arcs are merged in descending order of the merging degrees, which significantly improves the merging accuracy. During the merging process, multiple properties of ellipses are utilized to filter line segment/elliptical arc pairs, making the method very efficient. In addition, an ellipse-fitting method is proposed that restricts the maximum ratio of the semimajor axis and the semiminor axis, further improving the merging accuracy. Experimental results indicate that the proposed method is robust to outliers, noise, and partial occlusion and is fast enough for real-time applications.

scholarly journals Star Centroiding Based on Fast Gaussian Fitting for Star Sensors

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 2836 ◽  
Author(s):  
Xiaowei Wan ◽  
Gangyi Wang ◽  
Xinguo Wei ◽  
Jian Li ◽  
Guangjun Zhang
Keyword(s):  
Real Time ◽  
Noise Intensity ◽  
High Efficiency ◽  
Gaussian Function ◽  
High Accuracy ◽  
Star Sensor ◽  
Gaussian Fitting ◽  
Fitting Method ◽  
Real Time Applications ◽  
Star Images

The most accurate star centroiding method for star sensors is the Gaussian fitting (GF) algorithm, because the intensity distribution of a star spot conforms to the Gaussian function, but the computational complexity of GF is too high for real-time applications. In this paper, we develop the fast Gaussian fitting method (FGF), which approximates the solution of the GF in a closed-form, thus significantly speeding up the GF algorithm. Based on the fast Gaussian fitting method, a novel star centroiding algorithm is proposed, which sequentially performs the FGF twice to calculate the star centroid: the first FGF step roughly calculates the Gaussian parameters of a star spot and the noise intensity of each pixel; subsequently the second FGF accurately calculates the star centroid utilizing the noise intensity provided in the first step. In this way, the proposed algorithm achieves both high accuracy and high efficiency. Both simulated star images and star sensor images are used to verify the performance of the algorithm. Experimental results show that the accuracy of the proposed algorithm is almost the same as the GF algorithm, higher than most existing centroiding algorithms, meanwhile, the proposed algorithm is about 15 times faster than the GF algorithm, making it suitable for real-time applications.

scholarly journals Cut-Edge Detection Method for Rice Harvesting Based on Machine Vision

Agronomy ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 590
Author(s):  
Zhenqian Zhang ◽  
Ruyue Cao ◽  
Cheng Peng ◽  
Renjie Liu ◽  
Yifan Sun ◽  
...  
Keyword(s):  
Machine Vision ◽  
Edge Detection ◽  
Detection Method ◽  
Region Of Interest ◽  
Average Error ◽  
Vertical Projection ◽  
Cut Edge ◽  
Fitting Method ◽  
Combine Harvester ◽  
Edge Detection Method

A cut-edge detection method based on machine vision was developed for obtaining the navigation path of a combine harvester. First, the Cr component in the YCbCr color model was selected as the grayscale feature factor. Then, by detecting the end of the crop row, judging the target demarcation and getting the feature points, the region of interest (ROI) was automatically gained. Subsequently, the vertical projection was applied to reduce the noise. All the points in the ROI were calculated, and a dividing point was found in each row. The hierarchical clustering method was used to extract the outliers. At last, the polynomial fitting method was used to acquire the straight or curved cut-edge. The results gained from the samples showed that the average error for locating the cut-edge was 2.84 cm. The method was capable of providing support for the automatic navigation of a combine harvester.

High-Accuracy Ultrasound Contrast Agent Detection Method for Diagnostic Ultrasound Imaging Systems

2015 ◽  
Vol 41 (12) ◽  
pp. 3120-3130 ◽  
Author(s):  
Koichi Ito ◽  
Kazumasa Noro ◽  
Yukari Yanagisawa ◽  
Maya Sakamoto ◽  
Shiro Mori ◽  
...  
Keyword(s):  
Contrast Agent ◽  
Ultrasound Imaging ◽  
Detection Method ◽  
Ultrasound Contrast Agent ◽  
Diagnostic Ultrasound ◽  
High Accuracy ◽  
Imaging Systems ◽  
Ultrasound Contrast

scholarly journals Narrow-Angle and Wide-Angle Astrometry via Long Baseline Optical/Infrared Interferometers

1995 ◽  
Vol 166 ◽  
pp. 13-18
Author(s):  
Xiaopei Pan ◽  
Shri Kulkarni ◽  
Michael Shao ◽  
M. Mark Colavita
Keyword(s):  
Dynamic Range ◽  
Semimajor Axis ◽  
High Accuracy ◽  
Primary Component ◽  
Spectroscopic Binaries ◽  
High Angular Resolution ◽  
Maximum Magnitude ◽  
Wide Angle ◽  
Narrow Angle ◽  
Long Baseline

Long baseline optical/infrared interferometers, such as the Mark III Stellar Interferometer1 on Mt. Wilson and the ASEPS-0 Testbed Interferometer2 on Palomar Mountain, California, have good capabilities for narrow-angle and wide-angle astrometry with very high precision. Using the Mark III Interferometer many spectroscopic binaries became “visual” for the first time. The measurement accuracy of angular separation is 0.2 mas, the smallest separation measured between two components is 2 mas, the maximum magnitude difference is 4 mag, and the smallest semimajor axis is 4 mas. Such high angular resolution and dynamic range have been used to determine stellar masses with precision of 2% and differential stellar luminosities to better than 0.05 mag for separations of less than 0.″2. For some binary stars, not only have the systems been resolved, but also the diameter of the primary component has been determined, yielding direct measurements of stellar effective temperature with high accuracy. For parallax determination, the precision is 1 mas or better and is unaffected by interstellar extinction. For wide-angle astrometry with the Mark III interferometer, the observation results yielded average formal 1σ errors for FK5 stars of about 10 mas. Presently a new infrared interferometer, the ASEPS-0 Testbed Interferometer on Palomar Mountain is under construction, and is being optimized to perform high accuracy narrow-angle astrometry using long baseline observations at 2.2 μm, with phase referencing for increased sensitivity. The goal is to demonstrate differential astrometric accuracies of 0.06–0.1 mas3 in order to allow for detection of extra-solar planets in the near future.

Sign in / Sign up

Export Citation Format

Share Document