Cmake does not create configuration files in /usr/local/lib/cmake

My goal:

I am trying to run ORBSlam3 in a vm hosted in my local machine.In order to that I need to install Eigen3 version 3.2.1 because latest version 3.4.4 that comes with packet manager has compatibility issues with the code I am running.

Steps I have taken:

Before installing Eigen3 I have also installed Pangolin using :

cd ~/Devgit clone https://github.com/stevenlovegrove/Pangolin.gitcd Pangolingit checkout 86eb4975fc4fc8b5d92148c2e370045ae9bf9f5dmkdir buildcd buildcmake .. -DCMAKE_BUILD_TYPE=Releasemake -j 3sudo make install

and opencv too using :

cd ~$ mkdir Dev && cd Dev$ git clone https://github.com/opencv/opencv.git$ cd opencv$ git checkout 3.2.0mkdir build$ cd build$ cmake -D CMAKE_BUILD_TYPE=Release -D WITH_CUDA=OFF -D CMAKE_INSTALL_PREFIX=/usr/local ..$ make -j 3$ sudo make install

As far as I know usr/local/include folder contains source code and in my case it contains 4 folders eigen3 opencv opencv2 pangolin

And my usr/local/lib/cmake folder only contains Pangolin folder which contains cmake configuration files.

I tried to build eigen3 using following code and could not generate .cmake files in usr/local/lib/cmake:

$ mkdir build$ cd build$ cmake -D CMAKE_BUILD_TYPE=Release -D CMAKE_INSTALL_PREFIX=/usr/local ..$ make $ sudo make install

When I run build.sh in my Orbslam3 folder I get following output:

-- Configuring incomplete, errors occurred!See also "/home/orbslamhost/Dev/ORB_SLAM3/build/CMakeFiles/CMakeOutput.log".Build type: Release-- Using flag -std=c++11.OPENCV VERSION:3.2.0CMake Error at CMakeLists.txt:47 (find_package):  By not providing "FindEigen3.cmake" in CMAKE_MODULE_PATH this project has  asked CMake to find a package configuration file provided by "Eigen3", but  CMake did not find one.  Could not find a package configuration file provided by "Eigen3" (requested  version 3.2.1) with any of the following names:    Eigen3Config.cmake    eigen3-config.cmake  Add the installation prefix of "Eigen3" to CMAKE_PREFIX_PATH or set"Eigen3_DIR" to a directory containing one of the above files.  If "Eigen3"  provides a separate development package or SDK, be sure it has been  installed.

My questions are:

1-Why can't I create Eigen3 configuration files while I can create Pangolin files with same command logic?

2- There is no opencv either but somehow it can be detected How is that possible?

I can edit the question to include files like CMakeLists.Since I don't know what is important or not I want to keep the question as simple as I can.I reviewed similar questions but I may not have been able to understand it because but I have not written any cmake or source code of the project myself I just added include_directories to CmakeFile in my ORBSlam3 project and it is my first time working with cmake.

EDIT:

I have noticed that my Opencv files are located in /usr/local/share/opencv but my Pangolin file is only located in usr/local/lib/cmake

EDIT2:

When I look at CMakeCache at my orbslam folder I found :

 //The directory containing a CMake configuration file for Eigen3.Eigen3_DIR:PATH=Eigen3_DIR-NOTFOUND//Directory of Eigen3G2O_EIGEN3_INCLUDE:PATH=/usr/include/eigen3//Build g2o with OpenMP support (EXPERIMENTAL)G2O_USE_OPENMP:BOOL=OFF//Value Computed by CMakeORB_SLAM3_BINARY_DIR:STATIC=/home/orbslamhost/Dev/ORB_SLAM3/build//Dependencies for the targetORB_SLAM3_LIB_DEPENDS:STATIC=general;opencv_calib3d;general;opencv_core;general;opencv_features2d;general;opencv_flann;general;opencv_highgui;general;opencv_imgcodecs;general;opencv_imgproc;general;openc$//Value Computed by CMakeORB_SLAM3_SOURCE_DIR:STATIC=/home/orbslamhost/Dev/ORB_SLAM3//The directory containing a CMake configuration file for OpenCV.OpenCV_DIR:PATH=/usr/local/share/OpenCV

I am not still certain why Opencv and Pangolin are located in different folders.