I am happy to merge a PR about this, but probably won't have the time to port it myself.

We will work on this soon.

I successfully released the project for ROS Noetic. Please follow:

1. ubuntu20.04 + ros-noetic

2. sudo apt install libqglviewer-dev-qt5 freeglut3-dev qtbase5-dev

3. the default opencv version is 3, please revise the related opencv codes same as the format of opencv4
   #include <opencv2/highgui/highgui.hpp> -> #include<opencv2/highgui/highgui_c.h>
   #include <opencv/cv.h> -> #include <opencv2/imgproc.hpp>
   #include <opencv/highgui.h> -> #include<opencv2/highgui/highgui_c.h>
   CV_LOAD_IMAGE_ANYDEPTH -> cv::IMREAD_ANYDEPTH

CMakeLists.txt
set(CMAKE_CXX_STANDARD 11) -> set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_FLAGS "-Wall -Wextra -fPIC") -> set(CMAKE_CXX_FLAGS "-Wall -Wextra -fPIC -pthread")

cloud.cpp
return make_shared(pcl_cloud); -> return boost::make_shared(pcl_cloud);

4. catkin build depth_clustering -DPYTHON_EXECUTABLE=/usr/bin/python3
   you should install catkin build tools by yourself.
   Please do not build in Anaconda environment becasue of the conflict of Qt version

Thanks to the steps above, for me one additional step needs to be added for it to work properly:

CMakeLists.txt line 93

elseif(${DISTRO} MATCHES "16.04" OR ${DISTRO} MATCHES "18.04") -> elseif(${DISTRO} MATCHES "16.04" OR ${DISTRO} MATCHES "18.04" OR ${DISTRO} MATCHES "20.04")