OPENCV2.4.9特征提取和匹配

在OpenCV中使用SIFT、SURT等需要头文件#include <opencv2/nonfree/nonfree.hpp>

同时需要初始化模块 initModule_nonfree();

通过定义FeatureDetector的对象可以使用多种特征检测方法。

Ptr<FeatureDetector> FeatureDetector::create(const string& detectorType);

detectorType包括：
“FAST” – FastFeatureDetector
“STAR” – StarFeatureDetector
“SIFT” – SIFT (nonfree module)
“SURF” – SURF (nonfree module)
“ORB” – ORB
“MSER” – MSER
“GFTT” – GoodFeaturesToTrackDetector
“HARRIS” – GoodFeaturesToTrackDetector with Harris detector enabled
“Dense” – DenseFeatureDetector
“SimpleBlob” – SimpleBlobDetector

通过定义DescriptorExtractor的对象创建特征向量生成器

Ptr<DescriptorExtractor>descriptor_extractor = DescriptorExtractor::create(const string& detectorType)

通过定义DescriptorMatcher的对象创建特征匹配器

Ptr<DescriptorMatcher>descriptor_matcher = DescriptorMatcher::create(const string& detectorType)