ellipse

问题 I use matplotlib 1.15.1 and I try to generate scattergrams like this: The ellipses have fixes size and are drawn with center coordinates, width, height and angle (provided from outside): I have no idea what their equotions are. g_ell_center = (0.8882, 0.8882) g_ell_width = 0.36401857095483 g_ell_height = 0.16928136341606 g_ellipse = patches.Ellipse(g_ell_center, g_ell_width, g_ell_height, angle=angle, fill=False, edgecolor='green', linewidth=2) This ellipses should mark normal and semi-normal

问题 Obviously, any shape drawable by other means can be drawn by a turtle. Circles and squares are easy rt 1 fd .0 and if ticks mod 100 = 0 [rt 90] fd 1 Super-ellipses not so much. (regular ellipses are not trivial either.) The Wikipedia article on super-ellipses if you need to be refreshed on the topic. Any input is appreciated. Using a pendown turtle is there way to make a super-ellipse that emerges from turtle movement? 回答1: I have 1/4 of it, I suppose you could piece-wise put the other three

问题 Here i try to find the upper arc and lower arc using image vector(contours of images) But It could n't gave Extract result. Suggest any other method to find upper and lower arc from images and their length. Here my code Mat image =cv::imread("thinning/20d.jpg"); int i=0,j=0,k=0,x=320; for(int y = 0; y < image.rows; y++) { if(image.at<Vec3b>(Point(x, y))[0] >= 250 && image.at<Vec3b>(Point(x, y))[1] >= 250 && image.at<Vec3b>(Point(x, y))[2] >= 250){ qDebug()<<x<<y; x1[i]=x; y1[i]=y; i=i+1; } }

问题 Here i try to find the upper arc and lower arc using image vector(contours of images) But It could n't gave Extract result. Suggest any other method to find upper and lower arc from images and their length. Here my code Mat image =cv::imread("thinning/20d.jpg"); int i=0,j=0,k=0,x=320; for(int y = 0; y < image.rows; y++) { if(image.at<Vec3b>(Point(x, y))[0] >= 250 && image.at<Vec3b>(Point(x, y))[1] >= 250 && image.at<Vec3b>(Point(x, y))[2] >= 250){ qDebug()<<x<<y; x1[i]=x; y1[i]=y; i=i+1; } }

问题 Here is the deal. I have multiple points (X,Y) that form an 'ellipse like' shape. I would like to evaluate/fit the 'best' ellipse possible and get its properties (a,b,F1,F2), or just the center of the ellipse. Any ideas/leads would be appreciated. Gilad. 回答1: There's a Matlab function fit_ellipse that can do the job. There's also this paper on methods for orthogonal distance fitting of ellipses. A web search for orthogonal ellipse fit will probably turn up a lot of other resources as well.

问题 Forum I've got a set of data that apparently forms an ellipse in 3D space (not an ellipsoid, but a curve in 3D). Being inspired by following thread http://au.mathworks.com/matlabcentral/newsreader/view_thread/65773 and with the help from someone ,I manage to get the optimization code running and outputs a set of best parameters x (vector). However, when I try to use this x to replicate the ellipse,the outcomes is a strange straight line in the space. I have been stacked on this for days.,

问题 By following this post one can draw an ellipse with a given shape matrix (A): library(car) A <- matrix(c(20.43, -8.59,-8.59, 24.03), nrow = 2) ellipse(c(-0.05, 0.09), shape=A, radius=1.44, col="red", lty=2, asp = 1) Now how to get the major/minor (pair of intersect points of the major/minor axis and the ellipse) vertices of this ellipse? 回答1: For practical purposes, @Tensibai's answer is probably good enough. Just use a large enough value for the segments argument so that the points give a

问题 I've been trying to solve a problem. I'm surprised I haven't been able to find anything really useful on the net. I know that from the eigenvalues of the covariance matrix of the ellipse, the major and the minor axis of the ellipse can be computed. As the following: a1 = 2*sqrt(e1) a2 = 2*sqrt(e2) where a1 and a2 are the major and minor axis, e1 and e2 are the eigenvalues of covariance matrix. My question is: given an edge points (xi,yi) of the image ellipse, how it possible to find the 2×2

问题 I'm trying to count given data points inside each ring of ellipse: The problem is that I have a function to check that: so for each ellipse, to make sure whether a point is in it, three inputs have to be calculated: def get_focal_point(r1,r2,center_x): # f = square root of r1-squared - r2-squared focal_dist = sqrt((r1**2) - (r2**2)) f1_x = center_x - focal_dist f2_x = center_x + focal_dist return f1_x, f2_x def get_distance(f1,f2,center_y,t_x,t_y): d1 = sqrt(((f1-t_x)**2) + ((center_y - t_y)*

问题 I'm trying to draw ellipses around points of a group on a graph, with matplotlib. I would like to obtain something like this: A dataset for a group (the red one for example) could look like this: [[-23.88315146 -3.26328266] # first point [-25.94906669 -1.47440904] # second point [-26.52423229 -4.84947907]] # third point I can easily draw the points on a graph, but I encounter problems to draw the ellipses. The ellipses have diameters of 2 * standard deviation , and its center has the