undefined reference to `LineDetection3D::LineDetection3D()'

[Abbsalehi]

Could you please assist me to fix this issue?

'Starting build...
/usr/bin/g++ -fdiagnostics-color=always -g /home/amirabb/Desktop/3D_line_detection/3DLineDetection-1/src/main.cpp -o /home/amirabb/Desktop/3D_line_detection/3DLineDetection-1/src/main
/usr/bin/ld: /tmp/ccL2cPu8.o: in function main': /home/amirabb/Desktop/3D_line_detection/3DLineDetection-1/src/main.cpp:125: undefined reference to LineDetection3D::LineDetection3D()'
/usr/bin/ld: /home/amirabb/Desktop/3D_line_detection/3DLineDetection-1/src/main.cpp:129: undefined reference to LineDetection3D::run(PointCloud<double>&, int, std::vector<PLANE, std::allocator<PLANE> >&, std::vector<std::vector<cv::Point3_<double>, std::allocator<cv::Point3_<double> > >, std::allocator<std::vector<cv::Point3_<double>, std::allocator<cv::Point3_<double> > > > >&, std::vector<double, std::allocator<double> >&)' /usr/bin/ld: /home/amirabb/Desktop/3D_line_detection/3DLineDetection-1/src/main.cpp:135: undefined reference to LineDetection3D::~LineDetection3D()'
/usr/bin/ld: /home/amirabb/Desktop/3D_line_detection/3DLineDetection-1/src/main.cpp:135: undefined reference to `LineDetection3D::~LineDetection3D()'
collect2: error: ld returned 1 exit status

Build finished with error(s).

• The terminal process terminated with exit code: -1.
• Terminal will be reused by tasks, press any key to close it'