There are five precisely straight lines ranging from 2.4 to 4.1 kilometers long with no less than four points each, highlighted in purple.  Keep in mind this is dense jungle vegetation where it would be next to impossible to see anywhere close to that far from any single point on this map.
 

The Master Line

One line in particular has unique qualities.  Line GMPU contains points that are used in each of the 5 lines.  Point U is the endpoint of three lines.  Not only is this the line that includes the center point of the circle, and cuts the circle into eights, but it also contains coded measurements.  

 

From the starting point to the second point is exactly one kilometer.  From the starting point to the third point is exactly one mile and from the starting point to the last point is exactly two nautical miles or two minutes of longitude.  Finally from the edge of our circle to the last point is exactly 1 kilometer.