A novel algorithm for estimating the relative rotation angle of solar azimuth through single-pixel rings from polar coordinate transformation for imaging polarization navigation sensors

Optik ◽  
2019 ◽  
Vol 178 ◽  
pp. 868-878 ◽  
Author(s):  
Le Guan ◽  
Sheng Liu ◽  
Jinkui Chu ◽  
Ran Zhang ◽  
Yongtai Chen ◽  
...  
Keyword(s):  
Coordinate Transformation ◽  
Rotation Angle ◽  
Relative Rotation ◽  
Polar Coordinate ◽  
Single Pixel ◽  
Novel Algorithm

Full Convolutional Neural Network with Multi-Scale Residual Model for Optic Cup and Disc Segmentation

2020 ◽  
Vol 10 (11) ◽  
pp. 2733-2738
Author(s):  
Yanxia Sun ◽  
Peiqing ◽  
Xiaoxu Geng ◽  
Haiying Wang ◽  
Jinke Wang ◽  
...  
Keyword(s):  
Neural Network ◽  
Convolutional Neural Network ◽  
Cost Function ◽  
Coordinate Transformation ◽  
State Of The Art ◽  
Fundus Images ◽  
Early Screening ◽  
Multi Scale ◽  
Optic Cup ◽  
Polar Coordinate

Accurate optic cup and optic disc (OC, OD) segmentation is the prerequisite for cup-disc ratio (CDR) calculation. In this paper, a new full convolutional neural network (FCN) with multi-scale residual module is proposed. Firstly, polar coordinate transformation was introduced to balance the CDR with space constraints, and CLAHE was implemented in fundus images for contrast enhancement. Secondly, W-Net-R model was proposed as the main framework, while the standard convolution unit was replaced by the multi-scale residual module. Finally, the multi-label cost function is utilized to guide its functioning. In the experiment, the REFUGE dataset was used for training, validation and testing. We obtained 0.979 and 0.904 for OD and OC segmentations on MIoU, which indicates a relative improvement of 4.04% and 3.55%, comparing with that of U-Net, respectively. Experiment results proved that our proposed method is superior to other state-of-the-art schemes on OC and OD segmentation, and could be a potential prospective tool for early screening of glaucoma.

Electronic Predistortion by Polar Coordinate Transformation Using the CORDIC Algorithm

2009 ◽  
Vol 27 (16) ◽  
pp. 3607-3613
Author(s):  
T. Sugihara ◽  
K. Goto ◽  
Y. Konishi ◽  
T. Mizuochi
Keyword(s):  
Coordinate Transformation ◽  
Cordic Algorithm ◽  
Polar Coordinate

Contour Extraction of Human with Single-Pixel Width

2010 ◽  
Vol 20-23 ◽  
pp. 376-381 ◽  
Author(s):  
Hao Zhang ◽  
Zhi Jing Liu ◽  
Hai Yong Zhao
Keyword(s):  
Image Processing ◽  
Gait Recognition ◽  
Contour Extraction ◽  
Point Set ◽  
Posture Recognition ◽  
Candidate Regions ◽  
Single Pixel ◽  
Human Silhouette ◽  
Novel Algorithm

A novel algorithm is presented to acquire accurate human contour. For current algorithms extracting contour with multi-pixels width, it is difficulty in obtaining accurate distance between centroid and any point on human contour for gait recognition. For connective human contour, we use candidate regions and vectors to calculate and compare the angles of adjoining vectors, so that we get point set of human contour and describe human contour of single-pixel width. For disjoint contour, image pre-processing is implemented to fuse disjoint silhouettes with their centroids. Subsequently, we go on performing the algorithm of complete contour to get accurate contour. This algorithm solves the problem that any point on human contour locates accurately. It takes the advantages in image processing of human silhouette, particularly in accurate extraction of human contour for gait or posture recognition.

The Review of Algorithms to Correct Barrel Distortion Image

2012 ◽  
Vol 628 ◽  
pp. 403-409 ◽  
Author(s):  
Min Qi ◽  
Xiao Xi Zhang ◽  
Da Jian Li ◽  
Yang Yu Fan
Keyword(s):  
Coordinate Transformation ◽  
Affine Transformation ◽  
Basic Theory ◽  
Degree Polynomial ◽  
Research Directions ◽  
Advantages And Disadvantages ◽  
Polynomial Transformation ◽  
Polar Coordinate ◽  
The Common ◽  
Barrel Distortion

Aiming at solving the problem of correcting barrel distortion of image, this paper concluded the common correction algorithms into three types which include Affine Transformation, Two Degree Polynomial Transformation and Polar Coordinate Transformation, and introduced the basic theory of each of their representative algorithm. Then, analyzed and compared the advantages and disadvantages of them according to the correction experiments. At last, pointed out the research directions and difficulties of this field. In conclusion, Polar Coordinate Transformation is the most appropriate method to correct barrel distortion image, and the improved algorithm based on Polar Coordinate Transformation is more flexible to work out current difficulties of this aspect.

Polar Coordinate Transformation based Dual Binary-Drive QPSK Modulation

2010 ◽  
Author(s):  
Tsuyoshi Yoshida ◽  
Takashi Sugihara ◽  
Kazushige Sawada ◽  
Katsuhiro Shimizu ◽  
Takashi Mizuochi
Keyword(s):  
Coordinate Transformation ◽  
Polar Coordinate

Three Kinds of Gear Transmission Nonlinear Dynamics Models

2013 ◽  
Vol 787 ◽  
pp. 765-770
Author(s):  
Li Juan Wu ◽  
Jin Yuan Tang ◽  
Si Yu Chen
Keyword(s):  
Nonlinear Dynamics ◽  
Numerical Simulation ◽  
Time Domain ◽  
Rotation Angle ◽  
Dynamic Responses ◽  
Relative Rotation ◽  
Dissipation Energy ◽  
Motion Equations ◽  
Low Speed ◽  
Dynamics Models

Based on the Lagranges equations, a new nonlinear dynamic gear model is established by introducing two variables of relative rotation angleand mean rotation angle. The motion equations derived with Lagranges equation exhibit nonlinear terms which are absent in the equations derived on Newtons equations. Combining with the numerical simulation, the dynamic responses in time domain and frequency domain are deduced, and it can be concluded that the responses at low speed of three different models are different. However, they are similar at the designed speed without the consideration of dissipation energy. On the contrary, the dynamic responses are similar at low speed and the simplified Newtons equation differs at the designed speed including dissipation energy.

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