Path taking wrong side of inaccessible cells

[hjabbot]

Further splitting near inaccessible cells is required during vessel performance (@foxm1's example)

[gecoombs]

Example generated by Maria:

Southern route (1x1 cell size):

Northern route (5x2.5 cell size):

[gecoombs]

Example with the new splitting strategy:

Southern route (5x2.5 cell size):