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From: Fin Raziel on 20 Jan 2010 18:03
Hello

I have a need to acquire and process images from a "Point Grey Research Chameleon" camera in MATLAB. I do not have the Image Acquisition Toolbox, however, I do have some C++ code making use of functions in OpenCV to do the acquisition and have been successful in compiling a C++ MEX file to get images into Matlab.

I have been developing my program further and making use of a particular OpenCV function "cvCreateImage" which results in a compilation error as follows:

g++ -Wall -fPIC -ansi -pthread -DMX_COMPAT_32 -DMATLAB_MEX_FILE -I/home/$USER$/matlab/extern/include -I/usr/local/include/opencv -c test2.cpp
test2.cpp: In function ‘void mexFunction(int, mxArray**, int, const mxArray**)’:
test2.cpp:32: warning: unused variable ‘frame_undistorted’
test2.cpp:39: warning: unused variable ‘intrinsic’
test2.cpp:40: warning: unused variable ‘distortion’
test2.cpp:48: warning: unused variable ‘mapx’
/home/$USER$/matlab/bin/mex -cxx CC='g++' CXX='g++' LD='g++' -L/usr/local/lib -lm -lcv -lhighgui -lcvaux -output test2 test2.o
test2.o: In function `mexFunction':
test2.cpp:(.text+0xe7): undefined reference to `cvCreateImage'
collect2: ld returned 1 exit status

mex: link of ' "test2.mexglx"' failed.

make: *** [test2.mexglx] Error 1



My system is running Ubuntu 9.04 and I'm using the following makefile to compile the code:


MEXSUFFIX = mexglx
MATLABHOME = /home/$USER$/matlab
MEX = $(MATLABHOME)/bin/mex
CXX = g++
CFLAGS = -Wall -fPIC -ansi -pthread -DMX_COMPAT_32 -DMATLAB_MEX_FILE

LIBS = -L/usr/local/lib -lm -lcv -lhighgui -lcvaux
INCLUDE = -I$(MATLABHOME)/extern/include -I/usr/local/include/opencv
MEXFLAGS = -cxx CC='$(CXX)' CXX='$(CXX)' LD='$(CXX)'
FILE = test2

$(FILE).$(MEXSUFFIX): $(FILE).o
$(MEX) $(MEXFLAGS) $(LIBS) -output $(FILE) $^

$(FILE).o: $(FILE).cpp
$(CXX) $(CFLAGS) $(INCLUDE) -c $^

clean:
rm -rf *.o *.mexglx *.bmp *.csv


Now if I compile just using g++ and don't have anything to do with Matlab it compiles fine. The corresponding makefile is as follows:

CC = g++

CFLAGS = -Wall

LIBS = -L /usr/local/lib -lm -lcv -lhighgui -lcvaux
INC = -I/usr/local/include/opencv

FILE = test2

${FILE} : ${FILE}.o
${CC} ${CFLAGS} ${OBJS} ${LIBS} ${FILE}.o -o ${FILE}

${FILE}.o: ${FILE}.cpp
${CC} ${CFLAGS} ${INC} -c ${FILE}.cpp

It seems there is some MATLAB related issue causing the linking error. Any ideas on how to fix this?

Cheers

Fin
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