The future of voxelOccupancyDetection and pointAtObjectServer apps

[PeterBowman]

We are undergoing a refactorization/cleanup and now it's the turn of these two applications. They look like a nice-to-have to me basing on their names, but in fact I don't know their exact purpose nor current state. All I can say is:

• voxelOccupancyDetection: according to @jgvictores this is close to basic pcl::VoxelGrid; works only with depth frames and has been mainly used in Xgnitive-related projects to detect the robot/person in the painting scenario.
• pointAtObjectServer: one half of a pair of apps that involved Microsoft's proprietary code, focused on a single demo and probably unused ever since; obsolete, requires a lot of work for revival.

ASWJ we are probably going to delete pointAtObjectServer, the above list points at its current state in the commit history in case anyone wants to give it another chance. Any further pointers on how it was supposed to work and the configuration/setup would be appreciated for that matter.

It is even more interesting to describe and document voxelOccupancyDetection. @RaulFdzbis last contributed to it in 2019.

[PeterBowman]

I have disabled voxelOccupancyDetection in ca77353 due to CMake configuration failures in Ubuntu 24.04 (CMake 3.28). There is an undefined MPI::MPI_C target that cannot be found if the project() is not instructed to find a C compiler.

Edit: this is actually a PCL thing, see b969a83.