TypeError: Argument given by name ('k') and position (2)

Question

Find below my opencv3 Python3 code to match objects which raises the following error:

TypeError: Argument given by name ('k') and position (2)

Here's the code:

import numpy as np
import cv2
import time
import distance
camera = cv2.VideoCapture(0)
sift = cv2.xfeatures2d.SIFT_create()
img = cv2.imread('/home/shar/bo.jpg')
imgTrainGray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
kpTrain = sift.detect(imgTrainGray,None)
kpTrain, desTrain = sift.compute(imgTrainGray, kpTrain)
FLANN_INDEX_KDTREE = 0
index_params = dict(algorithm = FLANN_INDEX_KDTREE, trees = 5)
search_params = dict(checks=50)  
flann = cv2.FlannBasedMatcher(index_params,search_params)

matches = flann.knnMatch(kpTrain,desTrain,k=2)

Ideas on how to fix it?

Answer 1

This worked for me

FLANN_INDEX_KDTREE = 0
index_params = dict(algorithm = FLANN_INDEX_KDTREE, trees = 5)
search_params = dict(checks=50)

flann = cv2.FlannBasedMatcher(index_params,search_params)
matches = flann.knnMatch(np.asarray(des1,np.float32),np.asarray(des2,np.float32),k=2)

Answer 2

You are trying to match keypoints and the descriptors - which is wrong. You need two images, first you find the keypoints in both of the images (points of interest). Then for each point you calculate a descriptor (again in both images). Finally, you use the Flann to find matches between the two images. See the example here.