CMAKE cannot find Boost - c++

Question

I am trying to build Point Cloud Library on Windows.
https://github.com/PointCloudLibrary/pcl
This library requires Boost library and I have installed it properly.
However, when I use CMAKE to build PCL, it complains that
CMake Error at C:/Program Files (x86)/CMake/share/cmake-3.3/Modules/FindBoost.cmake:1245 (message):
Unable to find the requested Boost libraries.
Unable to find the Boost header files. Please set BOOST_ROOT to the root
directory containing Boost or BOOST_INCLUDEDIR to the directory containing
Boost's headers.
Call Stack (most recent call first):
cmake/pcl_find_boost.cmake:37 (find_package)
CMakeLists.txt:399 (include)
I have BOOST_ROOT set in my environment variables:
Furthermore, CMAKE doesn't even show the BOOST_ROOT or BOOST_INCLUDEDIR variables in its variable name list:
Below is the pcl_find_boost.cmake file
# Find and set Boost flags
# If we would like to compile against a dynamically linked Boost
if(PCL_BUILD_WITH_BOOST_DYNAMIC_LINKING_WIN32 AND WIN32)
set(Boost_USE_STATIC_LIBS OFF)
set(Boost_USE_STATIC OFF)
set(Boost_USE_MULTITHREAD ON)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DBOOST_ALL_DYN_LINK -DBOOST_ALL_NO_LIB")
else(PCL_BUILD_WITH_BOOST_DYNAMIC_LINKING_WIN32 AND WIN32)
if(NOT PCL_SHARED_LIBS OR WIN32)
set(Boost_USE_STATIC_LIBS ON)
set(Boost_USE_STATIC ON)
endif(NOT PCL_SHARED_LIBS OR WIN32)
endif(PCL_BUILD_WITH_BOOST_DYNAMIC_LINKING_WIN32 AND WIN32)
if(${CMAKE_VERSION} VERSION_LESS 2.8.5)
SET(Boost_ADDITIONAL_VERSIONS "1.43" "1.43.0" "1.44" "1.44.0" "1.45" "1.45.0" "1.46.1" "1.46.0" "1.46" "1.47" "1.47.0")
else(${CMAKE_VERSION} VERSION_LESS 2.8.5)
SET(Boost_ADDITIONAL_VERSIONS "1.47" "1.47.0" "1.48" "1.48.0" "1.49" "1.49.0")
endif(${CMAKE_VERSION} VERSION_LESS 2.8.5)
# Disable the config mode of find_package(Boost)
set(Boost_NO_BOOST_CMAKE ON)
# Optional boost modules
find_package(Boost 1.40.0 QUIET COMPONENTS serialization mpi)
if(Boost_SERIALIZATION_FOUND)
set(BOOST_SERIALIZATION_FOUND TRUE)
endif(Boost_SERIALIZATION_FOUND)
# Required boost modules
if(WITH_OPENNI2)
set(BOOST_REQUIRED_MODULES system filesystem thread date_time iostreams chrono)
find_package(Boost 1.47.0 REQUIRED COMPONENTS ${BOOST_REQUIRED_MODULES})
else()
set(BOOST_REQUIRED_MODULES system filesystem thread date_time iostreams)
find_package(Boost 1.40.0 REQUIRED COMPONENTS ${BOOST_REQUIRED_MODULES})
endif()
if(Boost_FOUND)
set(BOOST_FOUND TRUE)
# Obtain diagnostic information about Boost's automatic linking outputted
# during compilation time.
add_definitions(${Boost_LIB_DIAGNOSTIC_DEFINITIONS})
include_directories(SYSTEM ${Boost_INCLUDE_DIRS})
link_directories(${Boost_LIBRARY_DIRS})
endif(Boost_FOUND)
Thanks in advance for the help!