OpenCV 3: List of available FeatureDetector::create() and DescriptorExtractor::create() options?

Question

edit: I was looking at the wrong OpenCV2 code example, there is no FeatureDetector::create in OpenCV3 - this was confusing me.

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Hey n

Answer 1

You have also the OpenCV documentation to have a list of OpenCV features:

• OpenCV 3.1 documentation
• OpenCV 3.1 contrib documentation

What I do to know if the feature is available only in keypoints detection or descriptor extraction or both is to read the corresponding paper linked in the documentation. It allows also to have a brief description of the features (for example if it is a binary descriptor, main advantages, etc.)

Other solution is to test each feature:

• if the call to detect() is ok (no exception thrown) ==> feature detection
• if the call to compute() is ok ==> feature extraction
• if the call to detectAndCompute() is ok ==> both
• or looking directly into the source code.

Maybe a more optimal solution exists...

Anyway, from my knowledge (feel free to correct me if I am wrong):

• BRISK: detector + descriptor
• ORB: detector + descriptor
• MSER: detector
• FAST: detector
• AGAST: detector
• GFFT: detector
• SimpleBlobDetector: detector
• KAZE: detector + descriptor
• AKAZE: detector + descriptor
• FREAK: descriptor
• StarDetector: detector
• BriefDescriptorExtractor: descriptor
• LUCID: descriptor
• LATCH: descriptor
• DAISY: descriptor
• MSDDetector: detector
• SIFT: detector + descriptor
• SURF: detector + descriptor

Also with OpenCV 3.1, the code is:

cv::Ptr<cv::Feature2D> kaze = cv::KAZE::create(); 
std::vector<cv::KeyPoint> kpts; 
cv::Mat descriptors; 
kaze->detect(matImg, kpts); 
kaze->compute(matImg, kpts, descriptors); 
kaze->detectAndCompute(matImg, cv::noArray(), kpts, descriptors);

cv::Ptr<cv::Feature2D> daisy = cv::xfeatures2d::DAISY::create(); //Contrib

To know which norm type to use:

  std::cout << "AKAZE: " << akaze->descriptorType() << " ; CV_8U=" << CV_8U << std::endl;
  std::cout << "AKAZE: " << akaze->defaultNorm() << " ; NORM_HAMMING=" << cv::NORM_HAMMING << std::endl;

Finally, why

No more features2d::create?