ubuntu16.04升级到20.04后报错 By not providing “FindEigen.cmake“

编译问题：

CMake Error at modules/perception/lidar/CMakeLists.txt:14 (find_package):
  By not providing "FindEigen.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "Eigen", but
  CMake did not find one.

  Could not find a package configuration file provided by "Eigen" with any of
  the following names:

    EigenConfig.cmake
    eigen-config.cmake

  Add the installation prefix of "Eigen" to CMAKE_PREFIX_PATH or set
  "Eigen_DIR" to a directory containing one of the above files.  If "Eigen"
  provides a separate development package or SDK, be sure it has been
  installed.

CMakeLists.txt

由于此时是通过sudo apt install libeigen3-dev安装的，在/usr/lib/cmake下面会有eigen的cmake文件，需要将原find_package(Eigen REQUIRED)改为find_package(Eigen3 REQUIRED)，这样就不会报找不到eigen了。