Photo theodolite
The photo or photo theodolite is an instrument often used in the past for terrestrial photogrammetry . It combines a measuring image camera working with photo plates with a precise aiming device or a theodolite . The device, which can be rotated on a tripod, is leveled with vials and can also be tilted (at least by fixed angles). The aiming and reading devices required for this correspond to a theodolite of low to medium accuracy.
Technical development
Simple photo theodolites for terrain photography or the police (e.g. accident photogrammetry ) emerged shortly before the turn of the century. Essentially, they were swiveling plate cameras with an attached or side-mounted visor. One goal of the next developments was to use both instruments centrically: either by exchanging them on the same substructure, or by using the photo lens for the telescopic sight as well (picture above).
More precise instruments were created between 1910 and 1930, mainly by the companies Starke & Kammerer in Vienna (universal phototheodolite), Carl Zeiss in Jena (aerotopograph) and Wild Heerbrugg (terrestrial measuring chamber). In addition, particularly robust devices were designed for expeditions to Africa (with tropical cameras ), Central Asia and the high mountains. A special development were stereo cameras that were mounted in parallel on a horizontal support so that both cameras had the same external orientation .
In the 1960s, newer types were still used for terrestrial recordings, for example for glaciology or the surveying of quarries ; the best-known set of instruments was the terrestrial light equipment (TAL) from Zeiss. After that, however, the phototheodolites lost their importance, mainly due to aerophotogrammetry (almost global availability of aerial images ) and the recordings of earth observation satellites .
literature
- Franz Ackerl: Geodesy and Photogrammetry Volume I, Verlag G. Fromme, Vienna 1956
- Hans Löschner: Introduction to Earth Image Measurement , Franz Deuticke, Leipzig and Vienna 1930