15-01-2014, 04:41 PM
AERIAL PHOTOGRAPHY
Defining Aerial Photography
The term "photography" is derived from two Greek words
meaning "light" (phos) and "writing" (graphien). From Greek
phōt- , the stem of phōs ‘light’, which is a unit of illumination.
Photography means the art, hobby, or profession of taking
photographs, and developing and printing the film or
processing the digitized array image.
Photography is production of permanent images by means of
the action of light on sensitized surfaces (film or array inside a
camera), which finally giving rise to a new form of visual art.
Aerial Photography means photography from the air.
The word ‘aerial’ originated in early 17th century. [Formed
from Latin aerius , from Greek aerios , from aēr ‘air’.]
Aerial Photography: An Overview
Aerial Photography is one of the most common, versatile and
economical forms of remote sensing.
It is a means of fixing time within the framework of space (de
Latil, 1961).
Aerial photography was the first method of remote sensing
and even used today in the era of satellite and electronic
scanners. Aerial photographs will still remain the most widely
used type of remote sensing data.
Aerial photographs were taken from balloons and kites as
early as the mid-1800s.
1858 - Gasper Felix Tournachon "Nadar" took the first aerial
photograph from a captive balloon from an altitude of 1,200
feet over Paris.
Aerial Cameras
Aerial photographs can be made with any type of camera (e.g. 35
mm small amateur or 70 mm or special cameras that are purpose
built meant for mapping).
Many successful applications have employed aerial photography
made from light aircraft with handheld 35 mm cameras.
For the aerial study of large areas, high geometric and radiometric
accuracy are required and these can only be obtained from by using
cameras that are purpose built.
Aerial camera are precision built and specifically designed to expose
a large number of films/photographs in rapid succession with the
ultimate in geometric fidelity and quality.
These cameras usually have a medium to large format, a high quality
lens, a large film magazine, a mount to hold the camera in a vertical
position and a motor drive.
Aerial Mapping (Single Lens) Camera
• Aerial mapping cameras (also called as metric or cartographic cameras)
are single lens frame cameras designed to provide extremely high
geometric image quality.
• They employ a low distortion lens system held in a fixed position
relative to the plane of the film.
• The film format size is commonly a square of 230 mm on a side. The
total width of the film used is 240 mm and the film magazine capacity
ranges up to film lengths of 120 metres.
• A frame of imagery is acquired with each opening of the camera
shutter, which is tripped at a set frequency by an electronic device
called an intervalometer.
• They are exclusively used in obtaining aerial photos for remote sensing
in general and photogrammetric mapping purposes in particular.