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POcan't find correct FAST-SURF matches when using openCV for android
 

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  1. POcan't find correct FAST-SURF matches when using openCV for android
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    <p>I'm using openCV for android to implement a logo detection algorithm. my goal now is to find a predefined logo in a picture I've taken with the android camera.</p> <p>I can't get ANY right matches.. I think this is very weird considering I'm almost only using openCV library functions.</p> <p>First I detect keypoints using FAST detector, my images are 500x500 in size afterwards I use SURF to describe these keypoints. with knn I ask for the 2 best matches, and elliminate those who don't have A ratio smaller than 0.6 (first.distance/ second.distance).</p> <p>I'm getting around 10 matches, but they are all wrong, when I draw every match (100+), they all seem to be wrong</p> <p>I can't see what I'm doing wrong here, does anyone have the same problem, or know what I'm doing wrong?</p> <pre><code> FeatureDetector FAST = FeatureDetector.create(FeatureDetector.FAST); // extract keypoints FAST.detect(image1, keypoints); FAST.detect(image2, logoKeypoints); DescriptorExtractor SurfExtractor = DescriptorExtractor .create(DescriptorExtractor.SURF); Mat descriptors = new Mat(); Mat logoDescriptors = new Mat(); SurfExtractor.compute(image1, keypoints, descriptors); SurfExtractor.compute(image2, logoKeypoints, logoDescriptors); List&lt;DMatch&gt; matches = new ArrayList&lt;DMatch&gt;(); matches = knn(descriptors, logoDescriptors); Scalar blue = new Scalar(0, 0, 255); Scalar red = new Scalar(255, 0, 0); Features2d.drawMatches(image2, logoKeypoints, image1, keypoints, matches, rgbout, blue, red); </code></pre>
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      1. POcan't find correct FAST-SURF matches when using openCV for android
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    1. COHave you tried SURF features on SURF keypoints?
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      1. USAndrey Kamaev
    2. COWhat is the knn function? Is it implemented correctly?
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    3. COi tried almost every combination... SIFT-SIFT SURF-SURF FAST-SURF ... every combination has the same problem. the knn function gives you the 2 best matches, by comparing these two matches you can find the matches that really jump out, and have the best chance of being a true positive
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