Q: "A boy preparing to throw a snowball" Does this mean that "The boy is near his snow fort."?
A: it is not possible to tell

Q: "People walking on a trail in a tree filled park." Does this mean that "people are hiking"?
A: yes

Q: "An impromptu toast among friends." Does this mean that "People are holding up their drinks."?
A: yes

Q: "A small kid wearing a helmet smiles while his father is doing some adjustment at its back." Does this mean that "They are about to rollerblade."?
A:
it is not possible to tell