When the United States entered WWII, there was great fear of a Japanese attack on the West Coast and its invaluable military infrastructure. One important site was the Lockheed Aircraft factory in Burbank, California. The Lockheed Vega factory was located next to Burbank's Union Airport, which it had purchased prior to the outbreak of the war. This factory was ultimately where almost 20,000 aircraft were produced for the war effort. Most notably, they produced 9,000 of the P-38 Lightning, the best fighter of the entire war. They also built 2,750 B-17 Flying Fortresses under license from Boeing. So it was pretty important. The decision was made to take steps to protect the entire site from air attack. Rather than take the conventional route and reinforce buildings, construct bunkers and ring the area with dozens of anti-aircraft guns, they decided to camouflage the entire factory so that it would be unable to be located from the air. This way any enemy reconnaissance would be unable to pinpoint the exact site of the factory complex.
The camouflage scheme devised was nothing short of genius. The entire factory, including the parking lots, outbuildings and everything was covered in a gigantic burlap tarp painted to give the impression of a rural neighborhood. There were rubber cars set, up, fake roads and houses. The illusion was finished with hundreds of fake trees and shrubs. The trees and shrubs were created from chicken wire treated with an adhesive and covered with feathers to provide a leafy texture.
The difference in perspective for pilots flying several thousand feet up completed erased the difference of a few feet from the ground to the top of the tarp
Whether the ruse would have been effective is an interesting question. Certainly if the Japanese were to discover through spies the nature of the disguise, it may have been totally ineffective. But a single recon plane, or a bomber group at 20,000 feet trying to defend its self from fighters and avoid ground fire might well miss it. Since this was well before many of today's navigation methods and visual identification was the only method available, it could have made all the difference of there had aver been an air raid.To me it just represents some of the amazing innovation, creativity, and effort that was what made the difference in many ways during the largest and most terrible war that history has seen.