Reading the rules for terrain on P20. In the example it illustrates a unit in a tower not being able to see an enemy unit in the dead zone behind a hill. Does the same logic apply to open features and linear obstacles? Or is it terrain type dependent? I can see lots of arguments here. If overlooking an area of rocky ground perhaps a target should be visible but maybe not for a wood. What about walls and hedgerows? Viewed from above I would think a target is concealed but still visible.