Disk reduction
In astronomy and geodesy, plate reduction is the process by which measurements on a photographic plate , now digital images , are converted into the system of star coordinates or geographic coordinates .
In the astronomical field, so-called connecting stars are used for this transformation of image coordinates ( , ) in right ascension and declination (α, δ) , the star locations of which are already known. Well-known landmarks are used in the geodetic area .
During the transformation - assuming a corresponding number of known stars or landmarks and transformation parameters - effects of optical distortion , possible plate skew , small distortions (e.g. with films instead of plates) and differential refraction can be modeled or eliminated.
Similar reductions are used in photogrammetry , where terrestrial control points take on the role of stars .
See also
- Astrometry , asteroid , orbit determination , star clusters , satellite geodesy , digital photography
- Right ascension , declination , star catalog ,
- Similarity , coordinate transformation , projection , systematic errors
literature
- Albert Schödlbauer : Geodetic Astronomy . Verlag de Gruyter, Berlin and New York 2000, 640 pages, especially page 562 and the following.