Stereo autograph
The stereo autograph (also stereo autograph ) is a complex measuring instrument for the stereoscopic evaluation of two partially overlapping aerial photographs . It combines (e) the highest precision (in the range of thousandths of a millimeter) with partial automation of the measuring process.
The observer places the aerial photographs to be evaluated (traditionally mostly photo plates with dimensions of 21 × 21 cm) under two mechanically connected measuring microscopes . While scanning the terrain stereoscopically (i.e. with a spatial visual impression) with measuring spindles and two crosshairs , the autograph registers both the position coordinates and the height of the topography or the set terrain or object points using mechanically simulated visual rays . The geometry of the respective image pair (inner and outer orientation ) must first be modeled using control points .
Measurements for the production of maps
For the basic data of maps , the spatial measurement on the aerial photos (after orientation) is carried out in five ways:
- Driving along the line structures visible in the aerial photos , in particular traffic routes , bodies of water and prominent terrain edges
- Approaching the localities and their outlines,
- Approaching individual points such as large churches , other large buildings , bridges, high-voltage pylons, wayside shrines, etc.
- Creation of the contour lines by the observer moving the measuring mark along the terrain at a constant height setting (see parallax ) ,
- important high points such as peaks, saddle points, hollows.
On the history of stereographers
The first stereographers for photogrammetry were designed by Eduard von Orel in 1907 . From 1909 the device was built by the Carl Zeiss company in Germany as the "Orel-Zeiss'scher Stereoautograph". From the 1950s, when the possibilities of modern surveying and construction technology also increased the importance of aerotriangulation , very complex instruments were built that allowed semi-automatic measuring processes (terrain profiles, contour lines , etc.), took up a space of up to several square meters and connected Apart from devices such as paper tape -Stanzer or plotter enabled.
The best known were the series of the Swiss company Wild-Heerbrugg (large devices A7 and A8, as well as hand-operated table devices such as the B8). In the 1990s , digital photography also began to establish itself in image measurement, which on the one hand brought the possibility of a smaller construction, and on the other hand advanced analytical photogrammetry to the highest levels of accuracy and broad applications.
literature
- E. Berchtold: The Wild Autograph . In: Swiss Journal for Surveying and Cultural Technology , Vol. 27, 1929, pp. 49–59. ( Digitized version )
- Fritz Baeschlin : On the theory of the Wild autograph . In: Swiss Journal for Surveying and Cultural Technology , Vol. 27, 1929, pp. 110–116. ( Digitized version )
Individual evidence
- ↑ Orel Eduard von. In: Austrian Biographical Lexicon 1815–1950 (ÖBL). Volume 7, Verlag der Österreichischen Akademie der Wissenschaften, Vienna 1978, ISBN 3-7001-0187-2 , p. 243 f. (Direct links on p. 243 , p. 244 ).