i always imagined that olives were harvested in bright sunshine (probably because the oil looks like molten sunshine in a bottle) but in fact you pick in the colder months...sitting in a tree, covered in layers, breathing fog, with hats, gloves, scarves and on Thursdays, something red, so that the hunters don't mistake you for a cinghiale (wild boar)....
there are various techniques for harvesting the olives and some places now use machines but on my sister and brother-in-laws place in Umbria, we mainly pick by hand (with a little bit of raking). it's called "milking" the olives...as it's very similar to the action for milking a cow (which gets you wondering whether you could move onto a dairy farm and whether the farmer would say...."your milking technique looks like you're picking olives"
picking by hand reduces the bruising of the fruit which leads to a better oil.
the first step is to drape a net around the tree.
these catch the olives as we pick
next...is to hoist yourself up some branches or climb the ladder or stand and pick the low-hanging fruit.
finally, once you've plucked every olive, you gather them in the net, and scoop them into a crate.