I think it's somewhere in Vantaa. But I've never been there.
Can you remember what the number of the bus was?
sorry, can't recall, although i might remember if you mention a few bus numbers that follow the general route ..
How long a bus ride was it to where you got off? And have you any idea of the general direction? That looks like it might've been in Espoo or Kirkkonummi just as well as Vantaa, if the direction was west instead of north. I'm assuming it was still within the capital region YTV ticket range.
If it took you outside Helsinki city limits, it will have been a 3-digit number, I think the Espoo direction mostly gets buses numbered 1xx or 2xx, while Vantaa gets a broader range of 3xx-6xx. Some individual numbers from these ranges will go further out than Espoo/Vantaa, though.