Aerial cameras are highly specialised instruments developed to enable accurate and consistent imagery of the earth to be obtained from an aircraft. They are referred to as "passive sensors" in that they detect and capture the natural light reflected from objects.
Over the years a number of different styles and camera formats have been used but the basics of geometry still needed to be adhered to when utilized for ground measurement and mapping.
Early film cameras were hand-held surveillance instruments used by various armies to obtain pictures of the enemy. These rapidly developed into high altitude "fixed to the aircraft" types that held rolls of film enabling many frames of photography to be exposed in single sorties. These frames overlapped each other by 60 per cent which enabled three dimensional models to be created of the earth's surface. These resulting stereo images were the main source of information for mapping and in particular, ground height depiction for many years.
Later developments in camera and film technology enabled infrared film to be used for specific imagery capture, but it was the advent of digital technology that enabled capture of not only the visible light spectrum but also radiation at either end of the visible light range.
Zeiss RMK film camera
Digital sensors are used in many platforms including satellite, manned aircraft, unmanned aircraft, land-based vehicles and in static placements. Digital cameras have a further advantage in that their imagery pixels can be used to create point cloud elevation data sets.
Digital cameras are similar to film cameras in that they come in a wide variety of formats and styles and each individual unit has to be specifically calibrated to enable accurate measurements of the ground to be obtained.
If using aerial photography/imagery for any purpose beyond simple viewing, e.g. accurate measurement, it is vital to know the camera/sensor calibration data associated with a particular image. This enables the processes used for correcting the imagery to allow for lens distortion and alignment errors that could produce significant accuracy issues in the final measurements.
Over the years of aerial photography in Tasmania, many different cameras have been utilized and every camera has its own particular orientation and lens distortion errors that need to be taken into calculations. The lens calibration data for the cameras the government has used, is available here as a series of pdfs which contain the calibration data and orientation parameters. These are listed first by the eras in which they were used and then by the particular camera and lens system.
1945 to 1971
Eagle IV March 1948 Calibrations
Eagle IX Cam 523 Lens No 201702 O6-12-1960 (5Mb)
Eagle IX Cam 523 Lens No 201702 25-11-1958 (666Kb)
Eagle IX Cam 602 Lens 9667 09-10-1951 Original (1Mb)
Eagle IX Cam 602 Lens 9667 09-10-1951 panel right (36Kb)
Eagle IX Cam 602 Lens 9667 09-10-1951 panel top (35Kb)
Wild RC5 & RC8
Wild RC5 Cam 210 Lens 32 115mm 20-08-1954 (6Mb)
Wild RC8 Lens 11-5Ag71 114mm 06-07-1972 fiducial coords (87Kb)
Wild RC8 Lens11-5Ag71 114mm 15-11-1966 calibration original (2Mb)
Wild RC8 Lens11-5Ag71 114mm 27-09-1963 calibration original (3Mb)
Wild RC8 Lens11-5Ag71 114mm 27-09-1963 panel bottom (54Kb)
Wild RC8 Lens21At91 210mm 27-09-1963 calibration (136Kb)
Wild RC8 Lens21At91 210mm 27-09-1963 calibration original (3Mb)
Wild RC8 Lens21At91 210mm 27-09-1963 panel left (146Kb)
Wiiliamson OSC-176 Lens 216714 18-11-1948 graph (12Mb)
Wiiliamson OSC-176 Lens 216714 18-11-1948 original (17Mb)
Wiiliamson OSC-176 Lens 216714 18-11-1948 panel right (59Kb)
Williamson OSC-170 Lens 201558 09-01-1948 Calibration (12Mb)
1971 to 2009
Zeiss LMK 89mm (121Kb)
Zeiss LMK 152mm (121Kb)
Zeiss RMK 153mm (117Kb)
Zeiss RMK 305mm (116Kb)
2010 to 2011
Wild RC20 Lens 13024 152-87mm 26-06-2008 original (95Kb)
Wild RC20 Lens 13024 152-87mm 26-06-2008 panel right (148Kb)
2011 to 2012
Wild RC30 Lens 13426 153-5mm 16-04-2004 original (92Kb)
Wild RC30 Lens 13426 153-5mm 16-04-2004 panel right (145Kb)