The 3D model is one of the few remaining files that is not converted to XML. The “.ac” file format is plain text and can be studied without special software tools. Many tools that understand this 3D data file format, one of which is Pretty Poly Editor (PPE) – which also uses the PLIB.
In December, most years, the 3D model in CVS changes.
Reading this XML, which explicitly indicates that the UFO model should be slightly transparent, will explain to the reader why the buildings could be seen through the model on the previous slide...