How to implement LSD in opencv 4.1.0

Question

I had implemented LSD in my open CV project. Every thing worked well until I upgraded opencv version from 4.0.0 to 4.1.0. Now I get error as

cv2.error: OpenCV(4.1.0) /io/opencv/modules/imgproc/src/lsd.cpp:143: error: (-213:The function/feature is not implemented) Implementation has been removed due original code license issues in function 'LineSegmentDetectorImpl'

It seems that due to some liscense issue this feature has been removed. How do I address this problem.

The error is shown in the following part of code :

cv2.createLineSegmentDetector(0)

Answer 1

In opencv 4, it is now called FastLineDetector. You need to first install opencv-contrib-python by using pip install opencv-contrib-python and then you can use the following implementation

img = cv2.imread(test_image, 0)
fld = cv2.ximgproc.createFastLineDetector()
lines = fld.detect(img)
result_img = fld.drawSegments(img,lines)