diff --git a/CONDA.md b/CONDA.md
index b1f6c9b0..a4e5b293 100644
--- a/CONDA.md
+++ b/CONDA.md
@@ -46,11 +46,19 @@ Now, you can launch pySLAM scripts.
 
 ## Deactivate `pyslam` conda environment 
 
-To deactivate the `pyslam` environment, use
+To deactivate the `pyslam` environment, run
 ```
 $ conda deactivate
 ```
 
+## Delete `pyslam` conda environment 
+
+To delete the `pyslam` environment, run
+```
+$ . pyenv-conda-delete.sh 
+```
+
+
 --- 
 # General Notes About Conda
 
diff --git a/PYTHON-VIRTUAL-ENVS.md b/PYTHON-VIRTUAL-ENVS.md
index ddfe4a8e..136ae404 100644
--- a/PYTHON-VIRTUAL-ENVS.md
+++ b/PYTHON-VIRTUAL-ENVS.md
@@ -1,8 +1,32 @@
 # pySLAM2 Virtual Environment 
 
+The following instructions allow you to create a custom `pyslam` virtual environment by using the package `python3-venv`. You will be able to run pyslam scripts within such environment. 
+
+## Basic Installation 
+
+In order to run `main_vo.py` with venv, get in the root of this repository and run the following command:
+```
+$ . pyenv-create.sh 
+```
+**N.B.**: do not forget the dot! (without '/' !)
+
+This will create a custom `pyslam` environment and will also activate it. 
+
+## Full Installation 
+
+In order to run `main_slam.py` with venv, get in the root of this repository and run the following command:
+```
+$ . install_all_venv.sh  
+```
+**N.B.**: do not forget the dot! (without '/' !)
+
+This will compile the required thirdparty packages and will also activate the created `pyslam` environment. 
+
+
+
 ## Create a `pyslam` python virtual environment 
 
-In order to create a custom `pyslam` python virtual environment, get in the root of this repository and run the following command: 
+You already see this above. In order to create a custom `pyslam` python virtual environment, get in the root of this repository and run the following command: 
 ```
 $ . pyenv-create.sh 
 ```
@@ -25,6 +49,13 @@ Run the command:
 $ deactivate 
 ```
 
+## Delete `pyslam` environment 
+
+To delete the `pyslam` environment, run
+```
+$ . pyenv-delete.sh 
+```
+
 
 --- 
 # General Notes About Python Virtual Environments 
diff --git a/TROUBLESHOOTING.md b/TROUBLESHOOTING.md
index 15d94017..a1e869c9 100644
--- a/TROUBLESHOOTING.md
+++ b/TROUBLESHOOTING.md
@@ -54,7 +54,9 @@ If you get an error message like
 import g2o 
 ModuleNotFoundError: No module named 'g2o' error
 ```
-it's very likely you have libraries compiled in a 'mixed' way. Then, try to clean everything with the script `clean.sh`, and follow the installation procedure again. 
+First of all, check if you have a compiled `thirdparty/g2opy/lib/g2o.cpython-*-linux-gnu.so`. If not, Did you use one of the install_all scripts? Depending on your selected working environment (native, conda, python3-venv), you need to launch its companion install_all script in order to actually install all the required libraries (including g2o). Please, read the install instruction in the main [README](./README.md) file. 
+
+On the other hand, if you already have a compiled `thirdparty/g2opy/lib/g2o.cpython-*-linux-gnu.so`, it's very likely you have libraries compiled in a 'mixed' way. Then, try to clean everything with the script `clean.sh`, and follow the installation procedure again (see the main [README](./README.md) file). 
 
 ### Problems with ROS and OpenCV
 
diff --git a/clean.sh b/clean.sh
index 1032ff40..7d6d64ca 100755
--- a/clean.sh
+++ b/clean.sh
@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 
-# clean thirdparty install and utils 
+# clean thirdparty install and compiled libraries  
 
 # ====================================================
 # import the utils 
@@ -14,7 +14,17 @@ print_blue "=================================================================="
 print_blue "clearning thirdparty packages and utils..."
 
 rm -Rf thirdparty/pangolin 
+
 rm -Rf thirdparty/g2opy
-rm -Rf thirdparty/protoc  # set by install_delf.sh 
+
+rm -Rf thirdparty/protoc                   # set by install_delf.sh 
+
 rm -Rf thirdparty/orbslam2_features/build
-rm -Rf cpp/utils/build  
\ No newline at end of file
+rm -Rf thirdparty/orbslam2_features/lib
+
+rm -Rf cpp/utils/build  
+rm -Rf cpp/utils/lib 
+
+
+# TODO
+# clean downloaded models 
\ No newline at end of file
diff --git a/cpp/utils/CMakeLists.txt b/cpp/utils/CMakeLists.txt
index 969903fe..d7913542 100644
--- a/cpp/utils/CMakeLists.txt
+++ b/cpp/utils/CMakeLists.txt
@@ -7,6 +7,8 @@ ENDIF()
 
 set(CMAKE_CXX_STANDARD 11)
 
+set(WITH_PYTHON_INTERP_CHECK OFF CACHE BOOL "Checking python interpreter") # to be activate when called within virtual python environment 
+
 set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS}  -O3 -march=native -fPIC -DNDEBUG")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -O3 -march=native -fPIC -DNDEBUG")
 
@@ -22,7 +24,16 @@ message(STATUS "opencv include: ${OpenCV_INCLUDE_DIRS}")
 message(STATUS "opencv lib dirs: ${OpenCV_INSTALL_PATH}")
 message(STATUS "opencv libs: ${OpenCV_LIBS}")
 
-find_package(PythonLibs)
+
+# the following 2 lines are added to correctly detect the python version 
+if(WITH_PYTHON_INTERP_CHECK)
+  message(STATUS "WITH_PYTHON_INTERP_CHECK: ${WITH_PYTHON_INTERP_CHECK}")
+  find_package(PythonInterp) 
+  find_package(PythonLibs)
+  message(STATUS "PythonInterp: ${PythonInterp}")
+  message(STATUS "PythonLibs: ${PythonLibs}")
+endif()
+
 
 include_directories(
     ${PYTHON_INCLUDE_DIRS}
diff --git a/cpp/utils/build.sh b/cpp/utils/build.sh
index bd3a813d..6632eb3f 100755
--- a/cpp/utils/build.sh
+++ b/cpp/utils/build.sh
@@ -6,11 +6,17 @@ if [ ! -d $1 ]; then
 fi
 }
 
-STARTING_DIR=`pwd`
+# ====================================================
+# check if we have external options
+EXTERNAL_OPTION=$1
+if [[ -n "$EXTERNAL_OPTION" ]]; then
+    echo "external option: $EXTERNAL_OPTION" 
+fi
+# ====================================================
 
 make_dir build
 cd build
-cmake ..
+cmake .. $EXTERNAL_OPTION
 make -j 4
 
-cd $STARTING_DIR
+cd ..
diff --git a/install_all.sh b/install_all.sh
index d956eb64..adfcd023 100755
--- a/install_all.sh
+++ b/install_all.sh
@@ -2,16 +2,16 @@
 
 #N.B: this install script allows you to run main_slam.py and all the scripts 
 
+set -e
+
 # ====================================================
 # import the utils 
 . bash_utils.sh 
 
 # ====================================================
 
-set -e
-
-# set up git submodules  
-./install_basic.sh 
+# install basic modules and set up git submodules  
+. install_basic.sh          # use . in order to inherit python env configuration and possible other env vars 
 
 # build and install thirdparty 
-./install_thirdparty.sh 
\ No newline at end of file
+. install_thirdparty.sh     # use . in order to inherit python env configuration and possible other env vars 
\ No newline at end of file
diff --git a/install_all_conda.sh b/install_all_conda.sh
index c44202e6..eb584197 100755
--- a/install_all_conda.sh
+++ b/install_all_conda.sh
@@ -8,16 +8,22 @@
 
 # ====================================================
 
-set -e
+#set -e
 
 # set up git submodules  
-./install_basic.sh 0 # the '0' is an option for skipping pip3 packages installation  
+. install_basic.sh 0 0 # the first '0' is an option for skipping pip3 packages installation (script install_pip3_packages.sh),
+                       # the second '0' is for skipping the install_cpp.sh script therein (that will be called below) 
 
 # create a pyslam environment within conda and activate it 
 . pyenv-conda-create.sh 
 
+export WITH_PYTHON_INTERP_CHECK=ON  # in order to detect the correct python interpreter 
+
+# build and install cpp stuff 
+. install_cpp.sh                    # use . in order to inherit python env configuration and other environment vars 
+
 # build and install thirdparty 
-. install_thirdparty.sh 
+. install_thirdparty.sh             # use . in order to inherit python env configuration and other environment vars 
 
 
 # N.B.:
diff --git a/install_all_venv.sh b/install_all_venv.sh
new file mode 100755
index 00000000..5c296c6f
--- /dev/null
+++ b/install_all_venv.sh
@@ -0,0 +1,36 @@
+#!/usr/bin/env bash
+
+#N.B: this install script allows you to run main_slam.py and all the scripts 
+
+# ====================================================
+# import the utils 
+. bash_utils.sh 
+
+# ====================================================
+
+#set -e
+
+# set up git submodules  
+. install_basic.sh 0 0 # the first '0' is an option for skipping pip3 packages installation (script install_pip3_packages.sh),
+                       # the second '0' is for skipping the install_cpp.sh script therein (that will be called below) 
+
+# create a pyslam environment within venv 
+. pyenv-create.sh 
+
+export WITH_PYTHON_INTERP_CHECK=ON  # in order to detect the correct python interpreter 
+
+# build and install cpp stuff 
+. install_cpp.sh                    # use . in order to inherit python env configuration and other environment vars 
+
+# build and install thirdparty 
+. install_thirdparty.sh             # use . in order to inherit python env configuration and other environment vars 
+
+
+# N.B.:
+# if your run into troubles with opencv xfeatures2D/SIFT/SURF then run the following commands into your pyslam environment 
+# $ pip3 uninstall opencv-contrib-python
+# $ pip3 install opencv-contrib-python==3.4.2.16
+
+# HACK (this is actually run inside the created pyenv environment ) 
+#pip uninstall opencv-contrib-python
+#pip install opencv-contrib-python==3.4.2.16
diff --git a/install_basic.sh b/install_basic.sh
index 9009dafd..9680fd81 100755
--- a/install_basic.sh
+++ b/install_basic.sh
@@ -1,7 +1,9 @@
 #!/usr/bin/env bash
 
 #N.B: this install script allows you to run main_vo.py and the test scripts 
-# echo "usage: ./${0##*/} <INSTALL_PIP3_PACKAGES>"   # the argument is optional 
+# echo "usage: ./${0##*/} <INSTALL_PIP3_PACKAGES> <INSTALL_CPP>"   # the arguments are optional 
+
+#set -e
 
 # ====================================================
 # import the utils 
@@ -10,29 +12,39 @@
 # ====================================================
 
 export INSTALL_PIP3_PACKAGES=1   # install pip3 packages by default 
-if [ $# -eq 1 ]; then
+if [ $# -ge 1 ]; then
     # check optional argument 
     INSTALL_PIP3_PACKAGES=$1
     echo INSTALL_PIP3_PACKAGES: $INSTALL_PIP3_PACKAGES
 fi
-# ====================================================
 
-set -e
+export INSTALL_CPP=1   # install cpp by default 
+if [ $# -ge 2 ]; then
+    # check optional argument 
+    INSTALL_CPP=$2
+    echo INSTALL_CPP: $INSTALL_CPP
+fi
+
+# ====================================================
 
 echo `pwd`
 
 # install system packages 
-./install_system_packages.sh
+. install_system_packages.sh     # use . in order to inherit python env configuration 
 
 # install pip3 packages 
 # N.B.: install_pip3_packages script can be skipped if you intend to use a virtual python environment 
 if [ $INSTALL_PIP3_PACKAGES -eq 1 ]; then
     echo 'installing pip3 packages'
-    ./install_pip3_packages.sh 
+    ./install_pip3_packages.sh   
 fi 
 
 # set up git submodules  
 ./install_git_modules.sh 
 
 # build and install cpp stuff 
-./install_cpp.sh 
+# N.B.: install_cpp script can be skipped here if you intend to use a virtual python environment 
+#       but it must be then called within your virtual python environment in order to properly install libs 
+if [ $INSTALL_CPP -eq 1 ]; then
+    ./install_cpp.sh                
+fi 
diff --git a/install_cpp.sh b/install_cpp.sh
index 4a850395..2bbeceeb 100755
--- a/install_cpp.sh
+++ b/install_cpp.sh
@@ -7,7 +7,23 @@
 
 # ====================================================
 
-set -e
+#set -e
+
+
+# ====================================================
+# check if we have external options
+EXTERNAL_OPTION=$1
+if [[ -n "$EXTERNAL_OPTION" ]]; then
+    echo "external option: $EXTERNAL_OPTION" 
+fi
+
+# check if we want to add a python interpreter check
+if [[ -n "$WITH_PYTHON_INTERP_CHECK" ]]; then
+    echo "WITH_PYTHON_INTERP_CHECK: $WITH_PYTHON_INTERP_CHECK " 
+    EXTERNAL_OPTION="$EXTERNAL_OPTION -DWITH_PYTHON_INTERP_CHECK=$WITH_PYTHON_INTERP_CHECK"
+fi
+# ====================================================
+
 
 print_blue '================================================'
 print_blue "Building and installing cpp ..."
@@ -16,8 +32,10 @@ cd cpp
 
 # build utils 
 cd utils 
-./build.sh
+. build.sh $EXTERNAL_OPTION       # use . in order to inherit python env configuration 
 cd ..
 
-# ... 
+cd .. 
+
+
 
diff --git a/install_delf.sh b/install_delf.sh
index 49c57259..740be723 100755
--- a/install_delf.sh
+++ b/install_delf.sh
@@ -10,7 +10,7 @@
 STARTING_DIR=`pwd`  # this should be the main folder directory of the repo
 
 
-set -e
+#set -e
 
 # N.B.: this must be run after having run the script install_git_modules.sh  
 
diff --git a/install_git_modules.sh b/install_git_modules.sh
index a5ac8959..f578ef0c 100755
--- a/install_git_modules.sh
+++ b/install_git_modules.sh
@@ -7,7 +7,7 @@
 
 # ====================================================
 
-set -e
+#set -e
 
 
 STARTING_DIR=`pwd`  # this should be the main folder directory of the repo
@@ -76,4 +76,5 @@ cd $STARTING_DIR
 
 
 # install delf   
-./install_delf.sh 
\ No newline at end of file
+./install_delf.sh 
+cd $STARTING_DIR
diff --git a/install_pip3_packages.sh b/install_pip3_packages.sh
index 95ec09b5..2ad412d6 100755
--- a/install_pip3_packages.sh
+++ b/install_pip3_packages.sh
@@ -7,7 +7,7 @@
 
 # ====================================================
 
-set -e
+#set -e
 
 print_blue '================================================'
 print_blue "Configuring and installing python packages ..."
diff --git a/install_system_packages.sh b/install_system_packages.sh
index 93e3682c..a3ad3b7a 100755
--- a/install_system_packages.sh
+++ b/install_system_packages.sh
@@ -7,7 +7,7 @@
 
 # ====================================================
 
-set -e
+#set -e
 
 print_blue '================================================'
 print_blue "Configuring and installing system packages ..."
diff --git a/install_thirdparty.sh b/install_thirdparty.sh
index 8a9030c0..752a2f8c 100755
--- a/install_thirdparty.sh
+++ b/install_thirdparty.sh
@@ -1,5 +1,6 @@
 #!/usr/bin/env bash
 
+#set -e
 
 # ====================================================
 # import the utils 
@@ -11,8 +12,6 @@ print_blue '================================================'
 print_blue "Building Thirdparty"
 print_blue '================================================'
 
-set -e
-
 STARTING_DIR=`pwd`  # this should be the main folder directory of the repo
 
 # ====================================================
@@ -20,6 +19,21 @@ STARTING_DIR=`pwd`  # this should be the main folder directory of the repo
 #./install_basic.sh 
 # ====================================================
 
+# ====================================================
+# check if we have external options
+EXTERNAL_OPTION=$1
+if [[ -n "$EXTERNAL_OPTION" ]]; then
+    echo "external option: $EXTERNAL_OPTION" 
+fi
+
+# check if we want to add a python interpreter check
+if [[ -n "$WITH_PYTHON_INTERP_CHECK" ]]; then
+    echo "WITH_PYTHON_INTERP_CHECK: $WITH_PYTHON_INTERP_CHECK " 
+    EXTERNAL_OPTION="$EXTERNAL_OPTION -DWITH_PYTHON_INTERP_CHECK=$WITH_PYTHON_INTERP_CHECK"
+fi
+# ====================================================
+
+
 echo '================================================'
 print_blue "Configuring and building thirdparty/Pangolin ..."
 
@@ -53,13 +67,15 @@ else
         cd pangolin
         PANGOLIN_UOIP_REVISION=3ac794a
         git checkout $PANGOLIN_UOIP_REVISION
-        cd ..        
+        cd ..      
+        # copy local changes 
+        cp ./pangolin_changes/python_CMakeLists.txt ./pangolin/python/CMakeLists.txt 
     fi
     cd pangolin
     if [ ! -f pangolin.cpython-*-linux-gnu.so ]; then   
         make_dir build   
         cd build
-        cmake .. -DBUILD_PANGOLIN_LIBREALSENSE=OFF # disable realsense 
+        cmake .. -DBUILD_PANGOLIN_LIBREALSENSE=OFF $EXTERNAL_OPTION # disable realsense 
         make -j8
         cd ..
         #python setup.py install
@@ -81,13 +97,14 @@ if [ ! -d g2opy ]; then
     cd ..
     # copy local changes 
     cp ./g2opy_changes/types_six_dof_expmap.h ./g2opy/python/types/sba/types_six_dof_expmap.h
-    cp ./g2opy_changes/sparse_optimizer.h ./g2opy/python/core/sparse_optimizer.h    
+    cp ./g2opy_changes/sparse_optimizer.h ./g2opy/python/core/sparse_optimizer.h   
+    cp ./g2opy_changes/python_CMakeLists.txt ./g2opy/python/CMakeLists.txt    
 fi
 cd g2opy
-if [ ! -f thirdparty/g2o.cpython-*-linux-gnu.so ]; then  
+if [ ! -f lib/g2o.cpython-*-linux-gnu.so ]; then  
     make_buid_dir
     cd build
-    cmake ..
+    cmake .. $EXTERNAL_OPTION
     make -j8
     cd ..
     #python3 setup.py install --user
@@ -97,6 +114,6 @@ cd $STARTING_DIR
 print_blue "=================================================================="
 print_blue "Configuring and building thirdparty/orbslam2_features ..."
 cd thirdparty/orbslam2_features
-. build.sh
+. build.sh $EXTERNAL_OPTION
 cd $STARTING_DIR
 
diff --git a/pyenv-create.sh b/pyenv-create.sh
index 85a3e6a8..f545ba4c 100755
--- a/pyenv-create.sh
+++ b/pyenv-create.sh
@@ -44,7 +44,7 @@ source $ENV_PATH/bin/activate
 pip3 install -r requirements-pip3.txt
 
 # HACK to fix opencv-contrib-python version!
-pip3 uninstall opencv-contrib-python
+pip3 uninstall opencv-contrib-python                # better to clean it before installing the right version 
 install_pip_package opencv-contrib-python==3.4.2.16 
 
 # N.B.: in order to activate the virtual environment run: 
diff --git a/pyenv-delete.sh b/pyenv-delete.sh
index c93d16b3..3544d08e 100755
--- a/pyenv-delete.sh
+++ b/pyenv-delete.sh
@@ -8,7 +8,7 @@ if [[ -z "${ENV_NAME}" ]]; then
     ENV_NAME='pyslam'
 fi
 
-ENVS_PATH=~/.python/venvs  # path where to group virtual environments 
+ENVS_PATH=~/.python/venvs            # path where to group virtual environments 
 ENV_PATH=$ENVS_PATH/$ENV_NAME        # path of the virtual environment we are creating 
  
 if [ -d $ENV_PATH ]; then 
diff --git a/thirdparty/g2opy_changes/python_CMakeLists.txt b/thirdparty/g2opy_changes/python_CMakeLists.txt
new file mode 100644
index 00000000..7fd81d29
--- /dev/null
+++ b/thirdparty/g2opy_changes/python_CMakeLists.txt
@@ -0,0 +1,44 @@
+set(WITH_PYTHON_INTERP_CHECK OFF CACHE BOOL "Checking python interpreter") # to be activate when called within virtual python environment 
+
+include_directories(${PROJECT_SOURCE_DIR})
+
+include_directories(${EIGEN3_INCLUDE_DIR})
+include_directories(${CHOLMOD_INCLUDE_DIR})
+include_directories(${CSPARSE_INCLUDE_DIR})
+
+# the following 2 lines are added to correctly detect the python version 
+if(WITH_PYTHON_INTERP_CHECK)
+  message(STATUS "WITH_PYTHON_INTERP_CHECK: ${WITH_PYTHON_INTERP_CHECK}")
+  find_package(PythonInterp) 
+  find_package(PythonLibs)
+  message(STATUS "PythonInterp: ${PythonInterp}")
+  message(STATUS "PythonLibs: ${PythonLibs}")
+endif()
+
+# pybind11 (version 2.2.1)
+LIST(APPEND CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR}/EXTERNAL/pybind11/tools)
+include_directories(${PROJECT_SOURCE_DIR}/EXTERNAL/pybind11/include)
+include(pybind11Tools)
+
+
+pybind11_add_module(g2o g2o.cpp)
+target_link_libraries(g2o PRIVATE 
+    core
+    solver_cholmod
+    solver_csparse
+    solver_eigen
+    solver_dense
+    solver_pcg
+    solver_slam2d_linear
+    solver_structure_only
+    types_data
+    types_icp
+    types_sba
+    types_sclam2d
+    types_sim3
+    types_slam2d
+    types_slam2d_addons
+    types_slam3d
+    types_slam3d_addons
+    contrib
+)
diff --git a/thirdparty/orbslam2_features/CMakeLists.txt b/thirdparty/orbslam2_features/CMakeLists.txt
index 6c1aa1f0..3ed35488 100644
--- a/thirdparty/orbslam2_features/CMakeLists.txt
+++ b/thirdparty/orbslam2_features/CMakeLists.txt
@@ -7,6 +7,8 @@ ENDIF()
 
 set(CMAKE_CXX_STANDARD 11)
 
+set(WITH_PYTHON_INTERP_CHECK OFF CACHE BOOL "Checking python interpreter") # to be activate when called within virtual python environment 
+
 set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS}  -O3 -march=native -fPIC -DNDEBUG")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -O3 -march=native -fPIC -DNDEBUG")
 
@@ -22,7 +24,16 @@ message(STATUS "opencv include: ${OpenCV_INCLUDE_DIRS}")
 message(STATUS "opencv lib dirs: ${OpenCV_INSTALL_PATH}")
 message(STATUS "opencv libs: ${OpenCV_LIBS}")
 
-find_package(PythonLibs)
+
+# the following 2 lines are added to correctly detect the python version 
+if(WITH_PYTHON_INTERP_CHECK)
+  message(STATUS "WITH_PYTHON_INTERP_CHECK: ${WITH_PYTHON_INTERP_CHECK}")
+  find_package(PythonInterp) 
+  find_package(PythonLibs)
+  message(STATUS "PythonInterp: ${PythonInterp}")
+  message(STATUS "PythonLibs: ${PythonLibs}")
+endif()
+
 
 include_directories(
     ${PYTHON_INCLUDE_DIRS}
@@ -36,4 +47,4 @@ add_subdirectory(pybind11)
 pybind11_add_module(orbslam2_features orb_extractor.cpp ORBextractor.cpp)
 target_link_libraries(orbslam2_features PRIVATE
     ${OpenCV_LIBS}    
-)
\ No newline at end of file
+)
diff --git a/thirdparty/orbslam2_features/build.sh b/thirdparty/orbslam2_features/build.sh
index bd3a813d..6632eb3f 100755
--- a/thirdparty/orbslam2_features/build.sh
+++ b/thirdparty/orbslam2_features/build.sh
@@ -6,11 +6,17 @@ if [ ! -d $1 ]; then
 fi
 }
 
-STARTING_DIR=`pwd`
+# ====================================================
+# check if we have external options
+EXTERNAL_OPTION=$1
+if [[ -n "$EXTERNAL_OPTION" ]]; then
+    echo "external option: $EXTERNAL_OPTION" 
+fi
+# ====================================================
 
 make_dir build
 cd build
-cmake ..
+cmake .. $EXTERNAL_OPTION
 make -j 4
 
-cd $STARTING_DIR
+cd ..
diff --git a/thirdparty/pangolin_changes/python_CMakeLists.txt b/thirdparty/pangolin_changes/python_CMakeLists.txt
new file mode 100644
index 00000000..bf7668cb
--- /dev/null
+++ b/thirdparty/pangolin_changes/python_CMakeLists.txt
@@ -0,0 +1,28 @@
+set(WITH_PYTHON_INTERP_CHECK OFF CACHE BOOL "Checking python interpreter") # to be activate when called within virtual python environment 
+
+include_directories(${PROJECT_SOURCE_DIR}/include)
+
+# Find Eigen3
+find_package(Eigen3 REQUIRED)
+include_directories(${EIGEN3_INCLUDE_DIR})
+
+# the following 2 lines are added to correctly detect the python version 
+if(WITH_PYTHON_INTERP_CHECK)
+  message(STATUS "WITH_PYTHON_INTERP_CHECK: ${WITH_PYTHON_INTERP_CHECK}")
+  find_package(PythonInterp) 
+  find_package(PythonLibs)
+  message(STATUS "PythonInterp: ${PythonInterp}")
+  message(STATUS "PythonLibs: ${PythonLibs}")
+endif()
+
+#find_package(pybind11)
+
+# pybind11 (version 2.2.1)
+LIST(APPEND CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR}/external/pybind11/tools)
+include_directories(${PROJECT_SOURCE_DIR}/external/pybind11/include)
+include(pybind11Tools)
+
+
+pybind11_add_module( pangolin pangolin.cpp )
+SET_TARGET_PROPERTIES(pangolin PROPERTIES LIBRARY_OUTPUT_DIRECTORY ${PROJECT_SOURCE_DIR})
+target_link_libraries(pangolin PRIVATE ${LIBRARY_NAME})