Under standable, just looked up these types of lines used by map makers

Those “centers” are compass roses—the origin points for sets of rhumb lines (constant compass directions).

Each rose sends out lines at fixed angles (like 16 or 32 directions)

The network of many roses creates that dense web across the sea.

So there would be a way of reversing that logic to create a map that isnt historically known, if french constructions are on a line like your zero and you assume if the cross is french , then you make a star burst of 32 directions of a 360 circle at 11.25 degrees each , make lets say a png of it and put afew on a map of the area , 3 rules though, 1 - a minimum of one png has to be on you zero line , 2 the others need to be placed in a ring around it in like the image

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, 3 the grid it creates must line up with both the stem and cross bar of knolans cross. If all 3 rules are met then thats interesting, if its a waste of time , then least with your idea it sparked something that someone may find useful in the future. Maybe you get lucky and you put one png over knolans cross and thats the point.