C++ openCV - createFisherFaceRecognizer was not declared in this scope

Question

I am trying to make a facerecognizer in C++ using openCV. But keep getting the following errors:

1) cv::face::createFisherFaceRecognizer(int, double), but this gives:

main.cpp:(.text+0x6a8): undefined reference to`cv::face::createFisherFaceRecognizer(int, double)'

2)face::FisherFaceRecognizer::create(), but this gives:

 error: ‘cv::face::FisherFaceRecognizer’ has not been declared

None of those work, what is the correct way so I can run my code (none of those commented lines worked...)?

I even reinstalled everything, because no one could help me out. This is the current situation:

General configuration for OpenCV 3.2.0 =====================================
  Version control:               unknown

  Extra modules:
    Location (extra):            /home/yalishanda/Downloads/opencv_contrib-3.2.0/modules
    Version control (extra):     unknown

  Platform:
    Timestamp:                   2017-07-04T08:29:50Z
    Host:                        Linux 4.8.0-36-generic x86_64
    CMake:                       3.5.1
    CMake generator:             Unix Makefiles
    CMake build tool:            /usr/bin/make
    Configuration:               Release

  C/C++:
    Built as dynamic libs?:      YES
    C++ Compiler:                /usr/bin/c++  (ver 5.4.0)
    C++ flags (Release):         -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wundef -Winit-self -Wpointer-arith -Wshadow -Wsign-promo -Wno-narrowing -Wno-delete-non-virtual-dtor -Wno-comment -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -msse -msse2 -mno-avx -msse3 -mno-ssse3 -mno-sse4.1 -mno-sse4.2 -ffunction-sections -fvisibility=hidden -fvisibility-inlines-hidden -O3 -DNDEBUG  -DNDEBUG
    C++ flags (Debug):           -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wundef -Winit-self -Wpointer-arith -Wshadow -Wsign-promo -Wno-narrowing -Wno-delete-non-virtual-dtor -Wno-comment -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -msse -msse2 -mno-avx -msse3 -mno-ssse3 -mno-sse4.1 -mno-sse4.2 -ffunction-sections -fvisibility=hidden -fvisibility-inlines-hidden -g  -O0 -DDEBUG -D_DEBUG
    C Compiler:                  /usr/bin/cc
    C flags (Release):           -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wshadow -Wno-narrowing -Wno-comment -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -msse -msse2 -mno-avx -msse3 -mno-ssse3 -mno-sse4.1 -mno-sse4.2 -ffunction-sections -fvisibility=hidden -O3 -DNDEBUG  -DNDEBUG
    C flags (Debug):             -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wshadow -Wno-narrowing -Wno-comment -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -msse -msse2 -mno-avx -msse3 -mno-ssse3 -mno-sse4.1 -mno-sse4.2 -ffunction-sections -fvisibility=hidden -g  -O0 -DDEBUG -D_DEBUG
    Linker flags (Release):
    Linker flags (Debug):
    ccache:                      NO
    Precompiled headers:         YES
    Extra dependencies:          /usr/lib/x86_64-linux-gnu/libpng.so /usr/lib/x86_64-linux-gnu/libz.so gtk-x11-2.0 gdk-x11-2.0 pangocairo-1.0 atk-1.0 cairo gdk_pixbuf-2.0 gio-2.0 pangoft2-1.0 pango-1.0 gobject-2.0 fontconfig freetype gthread-2.0 glib-2.0 dl m pthread rt
    3rdparty dependencies:       libjpeg libwebp libtiff libjasper IlmImf libprotobuf

  OpenCV modules:
    To be built:                 core flann imgproc ml photo reg surface_matching video dnn freetype fuzzy imgcodecs shape videoio highgui objdetect plot superres ts xobjdetect xphoto bgsegm bioinspired dpm face features2d line_descriptor saliency text calib3d ccalib datasets rgbd stereo tracking videostab xfeatures2d ximgproc aruco optflow phase_unwrapping stitching structured_light
    Disabled:                    world contrib_world
    Disabled by dependency:      -
    Unavailable:                 cudaarithm cudabgsegm cudacodec cudafeatures2d cudafilters cudaimgproc cudalegacy cudaobjdetect cudaoptflow cudastereo cudawarping cudev java python2 python3 viz cnn_3dobj cvv hdf matlab sfm

  GUI: 
    QT:                          NO
    GTK+ 2.x:                    YES (ver 2.24.30)
    GThread :                    YES (ver 2.48.2)
    GtkGlExt:                    NO
    OpenGL support:              NO
    VTK support:                 NO

  Media I/O: 
    ZLib:                        /usr/lib/x86_64-linux-gnu/libz.so (ver 1.2.8)
    JPEG:                        libjpeg (ver 90)
    WEBP:                        build (ver 0.3.1)
    PNG:                         /usr/lib/x86_64-linux-gnu/libpng.so (ver 1.2.54)
    TIFF:                        build (ver 42 - 4.0.2)
    JPEG 2000:                   build (ver 1.900.1)
    OpenEXR:                     build (ver 1.7.1)
    GDAL:                        NO
    GDCM:                        NO

  Video I/O:
    DC1394 1.x:                  NO
    DC1394 2.x:                  NO
    FFMPEG:                      NO
      avcodec:                   NO
      avformat:                  NO
      avutil:                    NO
      swscale:                   NO
      avresample:                NO
    GStreamer:                   NO
    OpenNI:                      NO
    OpenNI PrimeSensor Modules:  NO
    OpenNI2:                     NO
    PvAPI:                       NO
    GigEVisionSDK:               NO
    Aravis SDK:                  NO
    UniCap:                      NO
    UniCap ucil:                 NO
    V4L/V4L2:                    NO/YES
    XIMEA:                       NO
    Xine:                        NO
    gPhoto2:                     NO

  Parallel framework:            pthreads

  Other third-party libraries:
    Use IPP:                     9.0.1 [9.0.1]
         at:                     /home/yalishanda/Downloads/opencv-3.2.0/build/3rdparty/ippicv/ippicv_lnx
    Use IPP Async:               NO
    Use VA:                      NO
    Use Intel VA-API/OpenCL:     NO
    Use Lapack:                  NO
    Use Eigen:                   NO
    Use Cuda:                    NO
    Use OpenCL:                  YES
    Use OpenVX:                  NO
    Use custom HAL:              NO

  OpenCL:                        <Dynamic loading of OpenCL library>
    Include path:                /home/yalishanda/Downloads/opencv-3.2.0/3rdparty/include/opencl/1.2
    Use AMDFFT:                  NO
    Use AMDBLAS:                 NO

  Python 2:
    Interpreter:                 /usr/bin/python2.7 (ver 2.7.12)

  Python 3:
    Interpreter:                 /usr/bin/python3 (ver 3.5.2)

  Python (for build):            /usr/bin/python2.7

  Java:
    ant:                         NO
    JNI:                         NO
    Java wrappers:               NO
    Java tests:                  NO

  Matlab:                        Matlab not found or implicitly disabled

  Documentation:
    Doxygen:                     NO

  Tests and samples:
    Tests:                       YES
    Performance tests:           YES
    C/C++ Examples:              NO

  Install path:                  /usr/local

  cvconfig.h is in:              /home/yalishanda/Downloads/opencv-3.2.0/build
-----------------------------------------------------------------

This is the command with which I compile: ( https://pastebin.com/raw/1EB7jXZd )

g++ src/faceDetection.cpp src/faceRecognition.cpp main.cpp -L/usr/local/lib -lopencv_stitching -lopencv_superres -lopencv_videostab -lopencv_aruco -lopencv_bgsegm -lopencv_bioinspired -lopencv_ccalib -lopencv_dpm -lopencv_fuzzy -lopencv_line_descriptor -lopencv_optflow -lopencv_reg -lopencv_saliency -lopencv_stereo -lopencv_structured_light -lopencv_phase_unwrapping -lopencv_rgbd -lopencv_surface_matching -lopencv_tracking -lopencv_datasets -lopencv_text -lopencv_face -lopencv_plot -lopencv_dnn -lopencv_xfeatures2d -lopencv_shape -lopencv_video -lopencv_ximgproc -lopencv_calib3d -lopencv_features2d -lopencv_flann -lopencv_xobjdetect -lopencv_objdetect -lopencv_ml -lopencv_xphoto -lopencv_highgui -lopencv_videoio -lopencv_imgcodecs -lopencv_photo -lopencv_imgproc -lopencv_core -o main

sort of speaking already linking almost every library that exists in openCV.... What else can I add?

Answer 1

createFisherFaceRecognizer() must be declared before being used. Most likely you are missing an header file (.h). I couldn't understand from the doc which one is it. You must find which one declares this function.