Phantom BSP is a collision artifact which sometimes appears in Halo BSP tags compiled by the HEK's tool.exe. Ghostbuster is a command-line tool which detects and fixes these artifacts in-place by modifying the tag's node structure.
This tool can produce collision holes as a side effect and phantom BSP detection is limited. The project is now archived as there are better solutions to fixing phantom BSP (fixing nearly-coplanar surfaces), so please only use Ghostbuster as a last resort.
You will need Python 3 to use this tool. Clone this repository, or simply download ghostbuster.py and requirements.txt somewhere convenient. Install dependencies with pip install --user -r requirements.txt.
Ghostbuster modifies BSP tags in-place unless the -dryrun flag is added, so it is recommended to first backup the tag if it cannot be recompiled easily. From a command line:
python3 ghostbuster.py <path to BSP tag>Due to rounding errors and the nature of how phantom BSP are detected, the script may report and "fix" a number of false positives. This does not appear to be detrimental to the map.