Assume that we think of the World Map as an image (Land = 1.0, Water = 0.0). If we perform erosion and dilatation operation on this image then we will remove isthmuses of given width (depends on erosion strength, we use double 1.0 to represent land in order to posses greater flexibility of erosion strength). If we will produce difference of modified and original images we will obtain capes and isthmus Locations. Difference can be produced by:
diff = !modified & original
or
diff = original - modified
Now we may use sprawl and put them into Landmarks. We don't need to do anything more with this data - capes and isthmuses are detected and it is up to Military Advisor to decide whether they have military significance e.g. we are on one side of isthmus and enemy is on the other.
The same is true for straits.
