transformation

I'm trying to detect lines in a tennis court using openCV and hough transform. I would like to find horizontal and vertical lines in order to find intersection and finally detect the corner of the tennis court. Here the original image. But i have some problems. 1)I tried to use HoughLineP . Here the code : gray=cv2.cvtColor(img,cv2.COLOR_BGR2GRAY) edges = cv2.Canny(gray,100,200,apertureSize = 3) lines = cv2.HoughLinesP(edges, 1, np.pi/2, 6, None, 50, 10); for line in lines[0]: pt1 = (line[0],line[1]) pt2 = (line[2],line[3]) cv2.line(img, pt1, pt2, (0,0,255), 2) cv2.imshow('dst',img) return res

I'm currently trying to implement an alternate method to webcam-based AR using an external tracking system. I have everything in my environment configured save for the extrinsic calibration. I decided to use cv::solvePnP() as it supposedly does pretty much exactly I want, but after two weeks I am pulling my hair out trying to get it to work. A diagram below shows my configuration. c1 is my camera, c2 is the optical tracker I'm using, M is the tracked marker attached to the camera, and ch is the checkerboard. As it stands I pass in my image pixel coordinates acquired with cv:

What is the way to implement custom transformation (+ animation) on a view surface (similar to the images attached) ( not just the view bounds ). The question is mainly in what is the general way to do that (not exactly the 'water drop effect', but any examples would be appreciated for sure). I guess, that's some 'algorythmic' transformation of the layer layout 'grid', but not sure which way to 'dig' that in. (Another thought is that might be achieved with using some frameworks, however, I would still need to understand the core logic). UPDATE: Pretty good resource for animations lovers

The example in the link below is using findHomography to get the transformation between two sets of points. I want to limit the degrees of freedom used in the transformation so want to replace findHomography with estimateRigidTransform . http://docs.opencv.org/doc/tutorials/features2d/feature_homography/feature_homography.html#feature-homography Below I use estimateRigidTransform to get the transformation between the object and scene points. objPoints and scePoints are represented by vector <Point2f> . Mat H = estimateRigidTransform(objPoints, scePoints, false); Following the method used in

I want to use Sankey chart but with circle's instead of rectangles. I am following the example from Mike Bostock . I changed the code there to use circle by setting radius, but how to place the lines connecting nodes around circle. Any clue. Thanks. VividD first of all, I would like to tell you that I liked your idea. I will walk you through several simple steps needed to get a decent Sankey diagram with circles. The final result may not be ideal for your application, but I guess it may be useful for you as starting point. Once you get to know internal and external features of d3 Sankey plugin