[ROS] CMake Error at /opt/ros/noetic/share/catkin/cmake/empy.cmake:30 (message):

ROS 에러 발생

catkin_make 하는데 아래와 같은 에러가 발생함

-- Could NOT find PY_em (missing: PY_EM) 
CMake Error at /opt/ros/noetic/share/catkin/cmake/empy.cmake:30 (message):
  Unable to find either executable 'empy' or Python module 'em'...  try
  installing the package 'python3-empy'
Call Stack (most recent call first):
  /opt/ros/noetic/share/catkin/cmake/all.cmake:164 (include)
  /opt/ros/noetic/share/catkin/cmake/catkinConfig.cmake:20 (include)
  CMakeLists.txt:58 (find_package)


-- Configuring incomplete, errors occurred!
See also "/home/user/vision_ws/build/CMakeFiles/CMakeOutput.log".
Invoking "cmake" failed

---

해결 방법

pip install -U rosinstall msgpack empy defusedxml netifaces

위에 패키지들을 설치해주면 됨

ROS에서 virtualenv를 사용하려면 위와 같은 패키지들을 설치해야 함