Aerial Photograph Types
The County Assessor's office also uses aerial photographs to locate and identify property. There are several types of aerial photographs as listed below:
Aerial Photographic Enlargement
Aerial Photographic Enlargement is nothing more than a "blown-up" photograph. Neither tilt nor relief displacement are removed for these photographs. Because of this, you will not be able to make accurate measurements from the photo of from maps made from it. These photos are helpful for inventory of parcels and locating structures.
Rectified Aerial Photograph
Rectified Aerial Photograph is one in which distortions caused by tilt displacement have been removed. The rectification process is accomplished by projecting the photo image onto a flat surface that is tilted to eliminate the original tip and tilt of the aircraft. The objective is to project the image back to its correct shape and scale. Although relief displacement is not removed from rectified photographs, this type of photography provides acceptable accuracy for assessment mapping in areas of relatively flat terrain.
Ortho-Photographs look a lot like the other two types of aerial photographs. However, it has the accuracy of a map drawn from ground survey information because tilt and relief displacement have been eliminated. Measurements of a land surveyor on the ground should "fit" when plotted on a true-to-scale ortho-photograph. Distances and area calculations on an ortho photograph are usually extremely accurate, and property lines will correspond closely to physical features.
Digital Ortho-Photographs is an ortho photograph scanned or created in a digital format. These have the same accuracy as ortho photo sheets, but can be viewed and manipulated on the computer, with the capability to zoom in or out. This also provides us a method to lay property lines or any other data over the photo.