Currently we have a version of the poisson library within the code. As the directory is named poission4 I think the code could be based on Poisson V4 - but the current version is 13.74 (see here). Currently they are working on a CMake integration (see mkazhdan/PoissonRecon#231), so maybe we could integrate this as external dependency, so we do not need to maintain this code anymore (e.g. it contains some compiler warnings).