Usually filters will be introduced into the optical paths of aerial cameras. Their primary purpose is to reduce the effects of haze, both manmade and natural. Manmade haze will vary, depending on prevailing winds and other meteorological conditions. You will have to use your own particular experience to determine exactly how to handle the problem. It also is a major factor in aircraft navigation and can, under certain conditions, negate attempts to secure aerial photography on an otherwise cloudless day.

Many underdeveloped nations permit unrestricted agricultural burning during certain seasons. I found this to be true (15 years ago) over my wife's native Central America. The farmers would burn off the land prior to planting. Many March days were entirely cloudless, but the ground would be totally obscured even from an altitude of 1 km. Aerial photography, unless you were attempting to locate the offenders, would be practically useless under such conditions.

Certain areas of the world are also subject to natural haze in the atmosphere, which can degrade a photographic image.

The selection of filters is based solely on the job to be done. There are hundreds of kinds available. The publication Kodak Filters for Scientific and Technical Use will be of great value. One important rule to remember is: Never use any filter which might cause random or unknown distortions in the optical path if you plan to record accurate photo-grammetric data.