Flann functions unresolved externals

Question

I'm trying to run one of the tutorial examples from OpenCV. It is about finding a known object with use of Flann based key point matching. Code can be found on Features2D + Homography to find a known object.

I know you will ask "Did you link the libraries?" or similar question. Yes I have been using OpenCV for 3 weeks with various examples which make use of nearly all libraries. And there was no problem until this day.

So I added these library dependecies to Visual Studio's linker input settings. Include directories are also working fine.

C:\OpenCV2.4\lib\opencv_core242d.lib
C:\OpenCV2.4\lib\opencv_highgui242d.lib
C:\OpenCV2.4\lib\opencv_video242d.lib
C:\OpenCV2.4\lib\opencv_ml242d.lib
C:\OpenCV2.4\lib\opencv_legacy242d.lib
C:\OpenCV2.4\lib\opencv_imgproc242d.lib
C:\OpenCV2.4\lib\opencv_objdetect242d.lib
C:\OpenCV2.4\lib\opencv_flann242d.lib
C:\OpenCV2.4\lib\opencv_nonfree242d.lib
C:\OpenCV2.4\lib\opencv_calib3d242d.lib

The error I got is a linker error. It can't resolve Flann's functions.

1>------ Build started: Project: flannMatch, Configuration: Debug Win32 ------
1>flannMatch.obj : error LNK2019: unresolved external symbol "void __cdecl cv::drawMatches(class cv::Mat const &,class std::vector<class cv::KeyPoint,class std::allocator<class cv::KeyPoint> > const &,class cv::Mat const &,class std::vector<class cv::KeyPoint,class std::allocator<class cv::KeyPoint> > const &,class std::vector<struct cv::DMatch,class std::allocator<struct cv::DMatch> > const &,class cv::Mat &,class cv::Scalar_<double> const &,class cv::Scalar_<double> const &,class std::vector<char,class std::allocator<char> > const &,int)" (?drawMatches@cv@@YAXABVMat@1@ABV?$vector@VKeyPoint@cv@@V?$allocator@VKeyPoint@cv@@@std@@@std@@01ABV?$vector@UDMatch@cv@@V?$allocator@UDMatch@cv@@@std@@@4@AAV21@ABV?$Scalar_@N@1@4ABV?$vector@DV?$allocator@D@std@@@4@H@Z) referenced in function _main
1>flannMatch.obj : error LNK2019: unresolved external symbol "public: void __thiscall cv::DescriptorMatcher::match(class cv::Mat const &,class cv::Mat const &,class std::vector<struct cv::DMatch,class std::allocator<struct cv::DMatch> > &,class cv::Mat const &)const " (?match@DescriptorMatcher@cv@@QBEXABVMat@2@0AAV?$vector@UDMatch@cv@@V?$allocator@UDMatch@cv@@@std@@@std@@0@Z) referenced in function_main
1>flannMatch.obj : error LNK2019: unresolved external symbol "public: __thiscall cv::FlannBasedMatcher::FlannBasedMatcher(class cv::Ptr<struct cv::flann::IndexParams> const &,class cv::Ptr<struct cv::flann::SearchParams> const &)" (??0FlannBasedMatcher@cv@@QAE@ABV?$Ptr@UIndexParams@flann@cv@@@1@ABV?$Ptr@USearchParams@flann@cv@@@1@@Z) referenced in function _main
1>flannMatch.obj : error LNK2019: unresolved external symbol "public: void __thiscall cv::DescriptorExtractor::compute(class cv::Mat const &,class std::vector<class cv::KeyPoint,class std::allocator<class cv::KeyPoint> > &,class cv::Mat &)const " (?compute@DescriptorExtractor@cv@@QBEXABVMat@2@AAV?$vector@VKeyPoint@cv@@V?$allocator@VKeyPoint@cv@@@std@@@std@@AAV32@@Z) referenced in function _main
1>flannMatch.obj : error LNK2019: unresolved external symbol "public: void __thiscall cv::FeatureDetector::detect(class cv::Mat const &,class std::vector<class cv::KeyPoint,class std::allocator<class cv::KeyPoint> > &,class cv::Mat const &)const " (?detect@FeatureDetector@cv@@QBEXABVMat@2@AAV?$vector@VKeyPoint@cv@@V?$allocator@VKeyPoint@cv@@@std@@@std@@0@Z) referenced in function _main
1>flannMatch.obj : error LNK2019: unresolved external symbol "public: virtual __thiscall cv::DescriptorMatcher::~DescriptorMatcher(void)" (??1DescriptorMatcher@cv@@UAE@XZ) referenced in function "public: virtual __thiscall cv::FlannBasedMatcher::~FlannBasedMatcher(void)" (??1FlannBasedMatcher@cv@@UAE@XZ)
1>flannMatch.obj : error LNK2019: unresolved external symbol "public: virtual __thiscall cv::DescriptorMatcher::DescriptorCollection::~DescriptorCollection(void)" (??1DescriptorCollection@DescriptorMatcher@cv@@UAE@XZ) referenced in function "public: virtual __thiscall cv::FlannBasedMatcher::~FlannBasedMatcher(void)" (??1FlannBasedMatcher@cv@@UAE@XZ)
1>flannMatch.obj : error LNK2019: unresolved external symbol "public: virtual __thiscall cv::FeatureDetector::~FeatureDetector(void)" (??1FeatureDetector@cv@@UAE@XZ) referenced in function "public: virtual __thiscall cv::Feature2D::~Feature2D(void)" (??1Feature2D@cv@@UAE@XZ)
1>flannMatch.obj : error LNK2019: unresolved external symbol "public: virtual __thiscall cv::DescriptorExtractor::~DescriptorExtractor(void)" (??1DescriptorExtractor@cv@@UAE@XZ) referenced in function "public: virtual __thiscall cv::Feature2D::~Feature2D(void)" (??1Feature2D@cv@@UAE@XZ)

I also know that surf and sift was moved to nonfree, thanks to one of questions here. At first glance I thought it may be because I have two version of OpenCV (2.2 and 2.4) and thus it was making a difference. So I removed 2.2 and tried to run another program. It was working fine but still this error was not gone.

So my question, what am I missing here? Is there another library dependency? What is it that I can't see? Any help is appreciated.

--EDIT--

How could I not see it? I'm really sorry for posting an easy question like this. I feel so stupid. I had forgotten to add this dependency.

C:\OpenCV2.4\lib\opencv_features2d242d.lib

I dont think anybody would miss that again.

Answer 1

How could i not see it? I m really sorry for posting an easy question like this. I feel so stupid. I had forgotten to add this dependecy.

C:\OpenCV2.4\lib\opencv_features2d242d.lib

I dont think anybody would miss that again.