PHOTOMOD technologies give new opportunities for Earth survey from the board of International Space Station
During last years the Russian space experiment “URAGAN” (“HURRICANE”) on global ground-space monitoring and disaster management
has been carried out on the board the Russian segment of International Space Station (ISS).
ISS cosmonauts make earth surface photos using digital cameras Nikon D3, Nikon D3X with telephoto lens. With the help of these cameras
image of the objects is acquired in visible band with resolution up to 2,5 m. Objects survey is made by cosmonauts with hands or with special
tripod (support) ensuring camera fixation.
Racurs Company has developed calibration methodology for the digital cameras based on space survey of the ground test polygons. Calibration of on-board
cameras increases the metric accuracy of the cameras and improves georeferencing accuracy of images taken during space experiments.
Regions located not far from Sochi city were used as test polygons. Racurs has aerial survey data of this
territory with the scale 1:40 000 and GSD = 40 cm. This territory was chosen not accidentally, as it is preferably to use volumetric
(not flat) objects for cameras calibration. Images of the same territory with GSD = 2,5 m were made from the board of ISS.
The survey was made by Nicon D3X with telephoto lens AF-S Nikkor 600mm f/4 and teleconverter TC-17E.
On aerial survey materials, catalogues of the points for using them as ground control points during calibration were composed. More
than 20 GCP were measured on each test polygons. As a result of camera calibration for two different testing ground, practically
calibration values were obtained. Calculated deviations that were provoked by radial distortion were about 14 pixels on the long side
of the images and about 25 pixels at the corners. Camera calibration increases image georeference accuracy at about 2-3 times in accordance with control calculation.
Digital cameras calibration and the following images processing in PHOTOMOD not only level up georeferencing accuracy, but also allows
getting additional information about the objects.