Why the rosettes image may not be a map at all

[MarcoP]

And what this pattern designates in Walters?

It represents Earth: the pattern is in most cases filled with green and occurs in a number of diagrams representing "Earth" as "the World" (we would now say "planet Earth"). 

In You are not allowed to view links. Register or Login to view. it represents Earth ("Terre") as one of the Four Elements. I think the title in red above the illustration could translate "The Earth keeps itself at the exact center of the Universe".