OpenCV SURF function is not implemented

Question

When I try to run the sample find_obj.cpp or any OpenCV SURF program I get the following error in command prompt while executing the code. The project builds wi

Answer 1

Taken from this answer (why don't you google your question before asking?):

The SIFT and SURF code was moved in OpenCV v2.4 to a new module called nonfree. Make sure you are linking (DLL in Windlows) to it. In linux this library is called libopencv_nonfree.so.

Answer 2

For ubuntu the script at https://help.ubuntu.com/community/OpenCV can be modified for nonfree surf/sift use by adding

libopencv_nonfree

to the end of the sudo apt-get command, and

-D BUILD_opencv_nonfree=ON

to the end of the cmake command. It only worked for me after uninstalling everything I could find dealing with opencv from the software center. Incidentally the software center also had an opencv nonfree library, "libopencv-nonfree2.4" which didn't seem to help matters. I am not an expert in such stuff so I don't know if what I did is 100% right, but it allows commands such as

surf = cv2.SURF(400)

and

keypoints = surfDetector.detect(im)

to run which hadnt previously (the first caused a 'not found' type error while the second caused a segfault).

The version of opencv.sh which allowed me to use nonfree surf/sift pasted to http://pastebin.com/sQzDdx5i
The version that is working now is opencv-2.4.9 but possibly this would work for other versions as the script seems to be somewhat agnostic as do the lib names.

Answer 3

It's not a bug. SURF is located in nonfree module. To use it you should initialize nonfree module:

    #include <opencv2/nonfree/nonfree.hpp> 
    ... 
    cv::initModule_nonfree();

Answer 4

Recently, I am learning the SURF. For this question you can add the opencv_nonfree240d.lib and opencv_nonfree240.lib to your project's lib path.