The Bastion: Ground to Aerial View
To show the configuration of a bastion, even a simple one, maps and plans typically illustrated it from above. Since the soldier or civilian of the time was not a bird, the perspective was somewhat different from ground level, yielding a dissimilar impression of a bastion. To compare, below is a simplified computer simulation of a bastion, starting at the level people viewed bastions, with the viewpoint "levitating" to reveal the bastion's design.
Note that not even the ditch or moat can be seen from ground level.