- surely most of the maps are compilation of the older maps, so Antarctic slips have such flow too [1] but while seeing some info about the jesuit priest FerdinandV who became chinese court astrologer [2] pop up idea that except using older maps to compile this map, maybe also he mastered (or had have at hand) knowhow for "astral projection" as aetheric flights on this plane, which served among other also for mapping needs, i.e. x1 dont needed in all instances to be result of seafaring ...
... in chinese folklore tales exist such concept for sure [3] thus logically used such technique, which must acknowledge as hint came while searching his chinese name, which also appears on some modern novel where the same character has such connotation [3][3]
- what is interesting, while searching that, I've reached for me to far more important info than Antarctic mapping, i.e. video by chinese pal who found interesting link in the royal astronomers databases about Our Almighty Lord Jesus Christ and His Holly Resurrection as celestial phenomenon recorded by chinese astronomers back then [4][4] from what also could be taken notion, that as astrologers they could not have anyhow obtained such info about the event unless did indeed practiced astral techniques ,,, so mapping, in my opinion for granted, also could had have going by such means too, i.e. x2 dont needed to be result of seafaring ...