How do I make precise borders? It seems like there's some guesswork involved since the lines on the .pdn file you shared are generally 2 to 4 pixels wide. Is there another resource I'm missing somehow? I plan on doing my personal corner of the world (New England) once I get the hang of it.
The lines in the pdf are a reference only, they are converted into robinson projection from a lower resolution map, they need to be hand drawn comparing to more high resolution sources, using this methode HEART would have
at most a 2-4 pixel error margin which is good enough for now, but as I elaborated in my post above I am trying to get it even more accurate by cross referencing all the borders with other sources.
This is why simple tracing alone isn't good enough in my opinion, simple tracing is the progess we used to create the M-BAM and resulted in a large number of errors which at the time we thought we would just fix later but that never happened, its best I think to aim for the highest accuracy possible now than aim for that later.