faceRecognizer was not declared in this scope

Question

I am using 2.4.7 version of opencv that supports face recognition. However I am receiving the following error:

 /home/fereres/recognition-build-desktop- Qt_4_8_1_in_PATH__System__Release/../recognition/program.cpp:58: error: 'FaceRecognizer' was  not declared in this scope

EDIT: The program is working since I've just change computer. I've followed the same instructions to install OpenCV. What could be responsible for that error?? My QT pro file is the following:

       QT       += core
       QT       -= gui

      TARGET = identification
      CONFIG   += console/home/fereres/projectCV-build-desktop-        Qt_4_8_1_in_PATH__System__Release
      CONFIG   -= app_bundle

      TEMPLATE = app

      INCLUDEPATH += /home/fereres/Desktop/OpenCV/opencv-2.4.7/include/opencv \
      INCLUDEPATH += /home/fereres/Desktop/OpenCV/opencv-2.4.7/include/opencv2 \
      INCLUDEPATH +=  /home/fereres/Desktop/OpenCV/opencv-2.4.7/modules/core/include/opencv2/core

      LIBS += -L/home/fereres/Desktop/OpenCV/opencv-2.4.7/build/lib \
       -lopencv_core \
       -lopencv_imgproc \
       -lopencv_highgui \
       -lopencv_ml \
       -lopencv_video \
       -lopencv_features2d \
       -lopencv_calib3d \
       -lopencv_objdetect \
       -lopencv_contrib \
       -lopencv_legacy \
       -lopencv_flann

       SOURCES += \
          program.cpp \
          prediction.cpp \
          Detection.cpp

      HEADERS += \
          prediction.h \
          Detection.h

The compilation comes out without errors. However when I am running my application I got

 ./identification: error while loading shared libraries: libopencv_core.so.2.4: cannot  open shared object file: No such file or directory
  fereres@ubuntu:~/identification-build-desktop-Qt_4_8_1_in_PATH__System__Release$

The /usr/local/lib forlder includes only a python folder I couldn't locate my libs there.

EDIT2: I installed opencv again and now everything is working fine. I guess that the final step of installing opencv didn't work so my /usr/local folder was empty. Now everything is under control.

It's tough to help when you are giving important information at homeopathic doses. Did you remember to write using namespace cv;? — karlphillip
Yes. As I told in the initial post, my problem arose just when I change computer. The code is working fine. — Jose Ramon
Indeed you did, and this problem seems to be completely connected to paths. To be more specific, it's a problem between how you #include the header, and how the paths were setup in INCLUDEPATH (assuming they really exist in your machine). — karlphillip

karlphillip karlphillip · Accepted Answer · 2013-12-17T22:18:13

It's probably best for you to adjust the INCLUDEPATH initialization to the following, else every #include statement that refers to opencv2 at the beginning of the path will cause a compiling error:

INCLUDEPATH += "/home/fereres/Desktop/OpenCV/opencv-2.4.7/include" \
               "/home/fereres/Desktop/OpenCV/opencv-2.4.7/include/opencv" \
               "/home/fereres/Desktop/OpenCV/opencv-2.4.7/include/opencv2" \
               "/home/fereres/Desktop/OpenCV/opencv-2.4.7/modules/core/include/opencv2/core"

Then, at recognition/program.cpp don't forget to include the appropriate header file:

#include <opencv2/contrib/contrib.hpp>

Note: since you are using pkg-config to add all OpenCV libraries you won't need to do this, but for those people that are specifying the libraries individually, you guys need to add opencv_contrib to LIBS.

faceRecognizer was not declared in this scope

1 Answers