I use Google Earth. I pick a location and download the image. I select the size of the image compatible with the altitude I want to depict.
A project coming up is for a plane from a Russian Aerobatic team performing at the Paris Air Show. I have alread downloaded the image. I glue the printouts to a nice wood base and then dullcoat the image. I drill the hole before gluing the image for the base, then cut the hole carefully with a scalpel.
I have previously done a USS Akron over Lakehurst, and a B-47 over Homestead.