Currently template_structure.xml defines a <Vision> of 40. However, most structures define different values. Furthermore, many of the structures in the other/ folder, which inherit directly from template_structure.xml, have a <Vision> of 4 (perhaps because one tile is 4×4?), which is roughly the attack range of a melee unit.
- changes template_structure.xml vision to 1.
- inserts a vision of 40 in those files that used to inherit it.
- purges the vision of those other/ structures (this does not alter gameplay balance)
- removes 1 vision lines that are now unnecessary in other structures (outpost, palisades, walls, monument, pillar, arch)
A vision of 1 means the structure can't see its surroundings, but can be selected (unlike fields, which have 0 vision); this seems more generic than the arbitrary value of 40.
- [EDIT] Changed 1 to 4, because players are unable to see capture points or set rally points with a vision of 1 (spotted by @Freagarach).