| OpenCV 3.4.8 Open Source Computer Vision

Classes | Typedefs
Non-free 2D Features Algorithms
Extra 2D Features Framework

## Classes
class | cv::xfeatures2d::SIFT
| Class for extracting keypoints and computing descriptors using the Scale Invariant Feature Transform (SIFT) algorithm by D. Lowe [129] . More...
class | cv::xfeatures2d::SURF
| Class for extracting Speeded Up Robust Features from an image [12] . More...
class | cv::cuda::SURF_CUDA
| Class used for extracting Speeded Up Robust Features (SURF) from an image. : More...

## Typedefs
typedef SIFT | cv::xfeatures2d::SiftDescriptorExtractor
typedef SIFT | cv::xfeatures2d::SiftFeatureDetector
typedef SURF | cv::xfeatures2d::SurfDescriptorExtractor
typedef SURF | cv::xfeatures2d::SurfFeatureDetector

## Detailed Description

This section describes two popular algorithms for 2d feature detection, SIFT and SURF, that are known to be patented. You need to set the OPENCV_ENABLE_NONFREE option in cmake to use those. Use them at your own risk.

## Typedef Documentation

## § SiftDescriptorExtractor

typedef SIFT cv::xfeatures2d::SiftDescriptorExtractor

`#include <opencv2/xfeatures2d/nonfree.hpp>`

## § SiftFeatureDetector

typedef SIFT cv::xfeatures2d::SiftFeatureDetector

`#include <opencv2/xfeatures2d/nonfree.hpp>`

## § SurfDescriptorExtractor

typedef SURF cv::xfeatures2d::SurfDescriptorExtractor

`#include <opencv2/xfeatures2d/nonfree.hpp>`

## § SurfFeatureDetector

typedef SURF cv::xfeatures2d::SurfFeatureDetector

`#include <opencv2/xfeatures2d/nonfree.hpp>`