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Questions tagged [feature-descriptor]

Feature descriptor is a phrase in computer vision which is a way to describe the points of interest in a video or image.

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OpenCV ORB descriptor - how exactly is it stored in a set of bytes?

I'm currently using OpenCV's ORB features extractor and I did notice the strange (at least for me) way the ORB-descriptor is stored (it is basically a BRIEF-32 with a modification that is not relevant to my question). As some of you know ORB takes…
rbaleksandar
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Why does opencv FREAK extractor remove so many keypoints, specifically using ORB detector

I am using OpenCV 2.4.3 c++ interface to find matching points between two images. The first attempt was using SURF. The only problem is the consuming time, so I tried the new FREAK extractor. Using SURF for detection and FREAK for description, I…
min.yong.yoon
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OpenCV FREAK: Fast Retina KeyPoint descriptor

I am developing an application which involves the use of Freak descriptors, just released in the OpenCV2.4.2 version. In the documentation only two functions appear: The class constructor A confusing method selectPairs() I want to use my own…
Jav_Rock
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unable to implement descriptors in android

I am creating an application for finding matches between two images. I am not able to properly find match results. Matching methods give me the same number of descriptors as the input keypoints and I am also unable to draw this result. I am using…
user1296460
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OpenCV - Use FLANN with ORB descriptors to match features

I am using OpenCV 3.2 I am trying to use FLANN to match features descriptors in a faster way than brute force. // Ratio to the second neighbor to consider a good match. #define RATIO 0.75 void matchFeatures(const cv::Mat &query, const cv::Mat…
Santiago Gil
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Implementation of ORB

I just used an open source implementation of an ORB. How can I implement ORB further by adding new modules? What can I do from my end in order to get better results than just using an ORB. Am thinking of to use RANSAC for eliminating the outliers…
John
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How to apply RANSAC on SURF, SIFT and ORB matching results

I'm working on image processing. I want to match 2D Features and I did many tests on SURF, SIFT, ORB.How can I apply RANSAC on SURF/SIFT/ORB in OpenCV?
Haider
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How to train HOG and use my HOGDescriptor?

I want to training data and use HOG algorithm to detect pedestrian. Now I can use defaultHog.setSVMDetector(HOGDescriptor::getDefaultPeopleDetector()); in opencv to detection, but the result is not very good to my testing video. So I want to do…
flammxy
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Printing values of keypoint descriptor matrix opencv

I'm having some trouble printing the values of the descriptor matrix obtained through the use of the 'compute' method of any opencv descriptor extractor. I want to print the descriptor of a feature to a file one by one, but always when I access some…
Alberto A
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comparing HOG feature vectors without SVM

I am relatively a newbie to computer vision and now currently doing a learning project on shape detection where I have a fixed region of interest(ROI) in all the images where the object is most likely present and I have to compare their shapes to…
Sakthi Geek
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Efficient way for SIFT descriptor matching

There are 2 images A and B. I extract the keypoints (a[i] and b[i]) from them. I wonder how can I determine the matching between a[i] and b[j], efficiently? The obvious method comes to me is to compare each point in A with each point in B. But it…
vancexu
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Explanation of feature descriptors in computer vision and machine learning

I've started working with computer vision techniques quite a bit, mainly deep learning but I want to try and get a good understanding of the more traditional techniques as well for a good grounding. I have been playing around with some manual…
maracuja
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SURF interest point parameters

I want to give alternative interest points as input to SURF using the -p1 command (I'm using the authors implementation: http://www.vision.ee.ethz.ch/~surf/download.html). But I'm not sure what to make of the parameters. I need to give x,y,a,b,c…
Bart
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Finding nearest neighbours of radial segments

First, don't be scared by the looks of this question ;) I'm trying to implement a shape descriptor in matlab called Circular Blurred Shape Model, and part of this is to get a list of nearest neighbours for every radial segment as can be seen in…
sled
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How does the SiftDescriptorExtractor from OpenCV convert descriptor values?

I have a question about the last part of the SiftDescriptorExtractor job, I'm doing the following: SiftDescriptorExtractor extractor; Mat descriptors_object; extractor.compute( img_object, keypoints_object, descriptors_object ); Now I…
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