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Terminology

Index

Image that shows the coverage and numbering (flight and tile numbers) for aerial photos in a particular county/ date

Aerial number
System used to identify individual aerial photographic tiles consisting of the following information (usually printed along the top of the photo, from left to right): 1. Flight date; 2. County code; 3. Flight number; 4. Tile number.

County code/FIPS code
Two or three letter county symbol (before 1970) or a five-digit FIPS code (1970 and later) used in aerial photography for each county.

Flight number
Flight path of the aircraft taking the photographs (alphanumeric or numeric code). May be alpha, numeric, or a combination. Denotes a specific range of photos and follows the flight of the plane while it was taking the photos. There may be several different "flights" in a specific county/date.

Tile
Denotes a specific, single, aerial photograph. Hundreds of "tiles" may be in one flight (usually numbered).

JPEG 2000 (also called JP2)

File format of the downloaded images from the Aerial Photography: Florida Collection. Information on free JPEG 2000 viewers is available from the Florida Department of Environmental Protection (http://data.labins.org/2003/General/reference/graphics_tips.cfm) and the Irfanview software is available as freeware (http://www.irfanview.com/) and can be used to view, convert, and batch convert JP2 images.

 


Interpreting Aerial Photographs

Interpreting aerial photos isn't difficult. Aerial photographs are photographs presented with the same viewpoint as maps. The "bird's eye view" is familiar to anyone who has looked out an airplane window or seen video of a football stadium during a game.

For example, if you pick photos from the east or west coast, the shoreline will be clear, and you will know that any slightly irregular pattern beside the shore is almost certainly a salt marsh. In the picture on the right, the open water is to the right. It is bordered by wetlands (salt marshes) and beyond the marsh is sandy upland with scattered shrubs or trees.

A few hints can help you make better sense of any aerial photo. First, look at the big picture. You can tell some things about the photo instantly. Is it a city or a rural area? Is it a natural area or one where humans have made major changes to the face of the earth? If you know where the picture was taken, you have even more clues. For example, if you see small, fairly round bodies of water and the photo is from Florida, you can assume they are small sinkhole lakes formed by collapsing limestone caves. The same type of images in a photo of Wisconsin might be kettlehole ponds left from the period of the most recent ice age.

In the photo on the right, the dark rectangular areas are man-made ponds, The light areas around many of the houses are bare soil, indicating that the area is currently under construction.

Generally speaking, anything you see that is a straight line or a regular geometric shape was made by humans. Very few natural forms are regular in shape. For example, an area of trees or shrubs where plants are in straight rows may be an orchard, a nursery, a pine plantation or an orange grove. Similar vegetation without the element of straight rows is likely to be a natural forest or a park.

 


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