If you read the documentation it is mentioned this function implements the algorithm of: Suzuki, S. and Abe, K., Topological Structural Analysis of Digitized Binary Images by Border Following. CVGIP 30 1, pp 32-46 (1985) OpenCV is open source if you want to see how this is implemented just need to read the code: https://github.com/opencv/opencv/blob/master/modules/imgproc/src/contours.cpp#L1655 … Read more
Does plt.tricontourf(x,y,z) satisfy your requirements? It will plot filled contours for irregularly spaced data (non-rectilinear grid). You might also want to look into plt.tripcolor(). import numpy as np import matplotlib.pyplot as plt x = np.random.rand(100) y = np.random.rand(100) z = np.sin(x)+np.cos(y) f, ax = plt.subplots(1,2, sharex=True, sharey=True) ax[0].tripcolor(x,y,z) ax[1].tricontourf(x,y,z, 20) # choose 20 contour levels, … Read more
Change this line cvtColor( image, gray_image, CV_RGB2GRAY ); to std::vector<cv::Mat> channels; cv::Mat hsv; cv::cvtColor( image, hsv, CV_RGB2HSV ); cv::split(hsv, channels); gray_image = channels[0]; The problem seems to be that your hand in gray scale is very close to the gray background. I have applied Canny on the hue (color) because the skin color should be … Read more
You can get the vertices back by looping over collections and paths and using the iter_segments() method of matplotlib.path.Path. Here’s a function that returns the vertices as a set of nested lists of contour lines, contour sections and arrays of x,y vertices: import numpy as np def get_contour_verts(cn): contours = [] # for each contour … Read more
It is unclear in your question whether you want to actually crop out the information that is defined within the contour or mask out the information that isn’t relevant to the contour chosen. I’ll explore what to do in both situations. Masking out the information Assuming you ran cv2.findContours on your image, you will have … Read more
Here is an example on how to use a contour plot in an animation. It uses matplotlib.animation.FuncAnimation which makes it easy to turn blitting on and off. With blit=True it runs at ~64 fps on my machine, without blitting ~55 fps. Note that the interval must of course allow for the fast animation; setting it … Read more
This approach works only on points. You don’t need to create masks for this. The main idea is: Find defects on contour If I find at least two defects, find the two closest defects Remove from the contour the points between the two closest defects Restart from 1 on the new contour I get the … Read more
I got the answer from the OpenCV Stack Exchange site. Answer THE ANSWER: I bet you are using the current OpenCV’s master branch: here the return statements have changed, see http://docs.opencv.org/modules/imgproc/doc/structural_analysis_and_shape_descriptors.html?highlight=findcontours. Thus, change the corresponding line to read: _, contours, _= cv2.findContours(skin_ycrcb, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE) Or: since the current trunk is still not stable and you … Read more