Error with OpenCV while building

[eladden]

Got the following error while building

Errors << occupancy_grid_utils:make ~/catkin_ws/logs/occupancy_grid_utils/build.make.000.log
~/catkin_ws/src/occupancy_grid_utils/src/file.cpp: In function ‘void occupancy_grid_utils::loadMapFromFile(nav_msgs::GetMap::Response*, const char*, double, bool, double, double, double*)’:
~/catkin_ws/src/occupancy_grid_utils/src/file.cpp:91:27: error: ‘CV_BGR2GRAY’ was not declared in this scope
cvtColor(imgColor, img, CV_BGR2GRAY);
^~~~~~~~~~~

This is because OpenCV 3 and higher depreciated that constant.

The fix would be to change to cv::COLOR_BGR2GRAY

[martinmagnusson]

This works now in the noetic-devel branch. See #25.