Can't use OpenCV GeneralizedHoughTransform class with Python

Question

I'm trying to code a basic example of use of GeneralizedHoughBallard class using OpenCV 4.0.0 and Python 3.6. I have found an example for C++ here https://github.com/opencv/opencv/blob/4.0.0/samples/gpu/generalized_hough.cpp but no for Python.

When I try to create a new instance of GeneralizedHoughBallard class:

import cv2
alg = cv2.createGeneralizedHoughBallard()

I get the error: "AttributeError: module 'cv2.cv2' has no attribute 'createGeneralizedHoughBallard".

I've seen in the OpenCV source (https://github.com/opencv/opencv/blob/4.0.0/modules/imgproc/include/opencv2/imgproc.hpp) that createGeneralizedHoughBallard is declared with CV_EXPORTS so I suppose it should be possible to use with Python. I've tried to use another similar function that is declared in the same file (improc.hpp) for example: cv2.createCLAHE() and works fine.

What could be the problem?

Answer 1

Apparently it's called just GeneralizedHoughBallard

import cv2
print([x for x in dir(cv2) if 'Hough' in x])
print([x for x in dir(cv2) if x.startswith('create')])

['GeneralizedHough',
 'GeneralizedHoughBallard',
 'GeneralizedHoughGuil',
 'HoughCircles',
 'HoughLines',
 'HoughLinesP',
 'HoughLinesPointSet']
['createAffineTransformer',
 'createAlignMTB',
 'createBackgroundSubtractorKNN',
 'createBackgroundSubtractorMOG2',
 'createButton',
 'createCLAHE',
 'createCalibrateDebevec',
 'createCalibrateRobertson',
 'createChiHistogramCostExtractor',
 'createEMDHistogramCostExtractor',
 'createEMDL1HistogramCostExtractor',
 'createHanningWindow',
 'createHausdorffDistanceExtractor',
 'createLineSegmentDetector',
 'createMergeDebevec',
 'createMergeMertens',
 'createMergeRobertson',
 'createNormHistogramCostExtractor',
 'createShapeContextDistanceExtractor',
 'createThinPlateSplineShapeTransformer',
 'createTonemap',
 'createTonemapDrago',
 'createTonemapDurand',
 'createTonemapMantiuk',
 'createTonemapReinhard',
 'createTrackbar']