I need to compare 2 pictures to find similar lines among them. In both pictures I use LSD (Line Segments Detector) method, then I find lines and I know coordinates of start and end points of each line.
My question is: is there any function in OpenCV to find the slope and length of each line, so that I can compare them easily?
My environment is: OpenCV 3.1, C++ and Visual Studio 2015
Well, this is a math question.
Assume you have two points:
p2(x2,y2). Let's call
p1 the "start" and
p2 the "end" of the line segment, as you have called the points you have.
slope = (y2 - y1) / (x2 - x1) length = norm(p2 - p1)
cv::Point p1 = cv::Point(5,0); // "start" cv::Point p2 = cv::Point(10,0); // "end" // we know this is a horizontal line, then it should have // slope = 0 and length = 5. Let's see... // take care with division by zero caused by vertical lines double slope = (p2.y - p1.y) / (double)(p2.x - p1.x); // (0 - 0) / (10 - 5) -> 0/5 -> slope = 0 (that's correct, right?) double length = cv::norm(p2 - p1); // p_2 - p_1 = (5, 0) // norm((0,5)) = sqrt(5^2 + 0^2) = sqrt(25) -> length = 5 (that's correct, right?)