96 lines
2.8 KiB
Python
96 lines
2.8 KiB
Python
'''
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Feature homography
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==================
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Example of using features2d framework for interactive video homography matching.
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Usage
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-----
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feature_homography.py [<video source>]
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Keys
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----
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SPACE - set reference frame
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ESC - exit
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'''
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import numpy as np
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import cv2
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import video
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from common import draw_str, clock
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import sys
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detector = cv2.FastFeatureDetector(16, True)
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detector = cv2.GridAdaptedFeatureDetector(detector)
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extractor = cv2.DescriptorExtractor_create('ORB')
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FLANN_INDEX_KDTREE = 1
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FLANN_INDEX_LSH = 6
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flann_params= dict(algorithm = FLANN_INDEX_LSH,
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table_number = 6, # 12
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key_size = 12, # 20
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multi_probe_level = 1) #2
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matcher = cv2.FlannBasedMatcher(flann_params, {}) # bug : need to pass empty dict (#1329)
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green, red = (0, 255, 0), (0, 0, 255)
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if __name__ == '__main__':
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print __doc__
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try: src = sys.argv[1]
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except: src = 0
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cap = video.create_capture(src)
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ref_kp = None
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while True:
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ret, img = cap.read()
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vis = img.copy()
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kp = detector.detect(img)
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kp, desc = extractor.compute(img, kp)
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for p in kp:
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x, y = np.int32(p.pt)
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r = int(0.5*p.size)
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cv2.circle(vis, (x, y), r, (0, 255, 0))
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draw_str(vis, (20, 20), 'feature_n: %d' % len(kp))
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if ref_kp is not None:
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raw_matches = matcher.knnMatch(desc, 2)
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matches = []
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for m in raw_matches:
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if len(m) == 2:
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m1, m2 = m
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if m1.distance < m2.distance * 0.7:
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matches.append((m1.trainIdx, m1.queryIdx))
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match_n = len(matches)
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inlier_n = 0
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if match_n > 10:
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p0 = np.float32( [ref_kp[i].pt for i, j in matches] )
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p1 = np.float32( [kp[j].pt for i, j in matches] )
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H, status = cv2.findHomography(p0, p1, cv2.RANSAC, 10.0)
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inlier_n = sum(status)
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if inlier_n > 10:
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for (x1, y1), (x2, y2), inlier in zip(np.int32(p0), np.int32(p1), status):
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cv2.line(vis, (x1, y1), (x2, y2), (red, green)[inlier])
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h, w = img.shape[:2]
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overlay = cv2.warpPerspective(ref_img, H, (w, h))
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vis = cv2.addWeighted(vis, 0.5, overlay, 0.5, 0.0)
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draw_str(vis, (20, 40), 'matched: %d ( %d outliers )' % (match_n, match_n-inlier_n))
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cv2.imshow('img', vis)
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ch = 0xFF & cv2.waitKey(1)
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if ch == ord(' '):
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matcher.clear()
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matcher.add([desc])
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ref_kp = kp
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ref_img = img.copy()
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if ch == 27:
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break
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