We have been working on a new ghost effect in the yard this year. We strung a cable across the back of the yard and hung 3 ten foot black backdrops up. We sewed the seams of them together and made some sandbags to hold the bottoms down from blowing around.
We filmed our friend kids dressed in white walking along the backdrop. Then we can project their ghost images on the backdrop from a projector in the yard behind a tombstone. Looks pretty good.